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Doc-To-Help Standard Template Introduction 1

Introduction

What is NetSim? NetSim is an interactive tool for calculations of pipe networks for district

heating, district cooling and steam.

With NetSim, you can:

Dimension pipe networks

Optimise pumping

Optimise flow pipe temperatures

Minimise heat losses

NetSim includes:

A powerful graphical interface which is used to define the pipe

networks and calculation criteria.

An effective calculation drawing module.

A powerful graphic presentation of calculation results in the form of

charts, diagrams and tables.

Powerful export tools which directly export data to Excel format,

DXF/DWG and a number of raster formats.

Powerful import tools for importing data from a number of network

information systems on the market.

The manual This manual covers NetSim release 3.5

27/02/2017: Updated manual

Note that changes are made to software without updating the manual.

Basic principles

Basic elements

The calculation model for a network consists of the basic elements nodes and

pipes. All numerical information is linked to these elements. A node is

represented by a circle on the chart, while a pipe (comprising a supply pipe and a

return pipe) is represented by a line between two nodes.

Calculation model for a district heating network. Nodes and pipes.

Nodes The following can be simulated in nodes:

Loads produced from nominal or measured values at consumer level.

Alternatively, consumption can be given as zero.

Thermostatic bypass

Bypass with fixed diameter or Kv value

Production plants

Shunt valves

Accumulators

Doc-To-Help Standard Template Basic principles 3

In addition, the node is a coupling between one or more pipes (max. 8). The

model describes the nodes by providing names, coordinates, an elevation, a

cooling or return temperature and information on bypasses.

Model of a node and its potential controls.

Consumers can be divided into categories. This makes it possible to execute a

simulation with varying load factors depending on consumer category. The

consumer categories are defined by the user. Up to 99 different categories can be

defined. Categories are characterised by category type numbers (1 – 99) and

corresponding names. A factor by which the customer's recorded power

requirements is to be multiplied is indicated for every category as a function of

the outdoor temperature. In a similar way, type curves are defined for the

customer's cooling as a function of the outdoor temperature and the return

temperature as a function of the outdoor temperature.

Every consumer can belong to only one category, but a node can stand

in relation to many consumers with different categories.

A single node, such as a branch, is the same thing as a node without a

load.

A production plant is a node where supplements have been made to the

node information for supply temperature, possible production quantity

and absolute pressure.

The accumulators work in two ways:

The accumulator can be given an unknown power consumption. This

may be useful when the calculations are to be used as dimensioning

tools for accumulators.

The accumulator can be given a given power consumption with a set of

power factors. This allows the behaviour of an accumulator to be

checked.

The accumulators in question are expected to behave as follows:

Power is stored at a constant return temperature which is the same as

the accumulator's minimum temperature, Tmin, depending on the

stratification of the liquid in the accumulator.

When power is extracted, this takes place at a constant temperature

which is the same as the accumulator's maximum temperature, Tmax,

depending on the stratification of the liquid in the accumulator.

Pipes The pipes in the model are couplings between the nodes. Pumps, valves and heat

exchangers can be connected to pipes. A pipe is characterised by the name of the

connecting nodes, length, internal diameter, roughness, heat transfer coefficient,

individual loss, two pressure losses at both ends and the flow in the pipe.

The model assumes that the network is geometrically symmetrical from inlet to

return. Various physical units such as diameter, heat transfer coefficient,

individual loss, length and roughness can be specified. Pumps and valves can be

connected to either the upstream pipe end or the downstream pipe end; see the

figure.

Pipe model defined with lengths and pressures.

A pump can either be described with a pressure increase, ΔP, or by means of a

pump characteristic, where the pressure is calculated as a function of the flow in


the pipe. The pump velocity can also be calculated when the pressure and flow

are described by means of the characteristics. The pump characteristics are

indicated by up to 12 points which are described with pressure, flow and power

consumption at a specific velocity for the pump. Calculation of ΔP is

interpolated from the characteristics.

Specification of pump characteristics

A valve is indicated either by an applied pressure loss or by valve characteristics

where the pressure loss is calculated as a function of the flow in the pipe at a

given valve setting. The characteristics have to be entered as a set of operating

points determined by the values of the valve setting and valve coefficient. Up to

10 points can be entered for determination of the characteristics.

Specification of valve characteristics

A heat exchanger can be connected to a pipe end. Quite simply, the heat

exchanger describes an increased or a decreased temperature for the water in the

pipe. The power supplied or removed via the heat exchanger is a linear function

of the temperature upstream in the pipe.

Boundary conditions Like all other calculation models, NetSim needs specific input data. These

requirements are all quite simple and natural. A calculation model has to meet a

number of hydraulic and thermal requirements before a problem is defined and

can be resolved.

Fundamentally, the following conditions have to be met:

Flow or power consumption must be specified at all nodes except for

one.

An absolute pressure must be specified.

A differential pressure must be specified.

The cooling or return temperature must be specified at all nodes with

consumption.

The temperature in the supply pipe must be specified at production

plants (producers).

Pressure drop in a single pipe

The simplest possible system - one pipe and two nodes - is shown in the figure

above. This system meets the requirements for both pressure and differential

pressure and the flow being known at all nodes, except for one. The nodes in

which the flow and pressure are stated is of no significance.

In some cases, more than one pressure check must be specified; for example, if a

pressure increase or a pressure drop in a valve is to be calculated. In these cases,

more than one pressure must be known, one for every ΔP to be calculated. The

unknown pressure change must be positioned between the known absolute

pressures in relation to the direction of flow of the liquid.


Model

of a pipe network provided with a pump controlled to find a set pressure at the

end point

Pressure gradients for model defined in figure above

The two examples below show exceptions which may occur in respect of what

was described above:

If the unknown pressure P is set in a pipe which is part of a system

containing ring connections.

In a node, the known flow can be replaced by another known pressure.

The flow is then calculated on the basis of the calculated pressure

profiles.

Dimensioning NetSim can be used for dimensioning pipes. The user can specify which of three

criteria are to be used:

1. Maximum permitted velocity in the pipe.

2. Maximum permitted gradient in the pipe.

3. Dimension-dependent criterion where a velocity criterion is used if the

diameter is less than a diameter specified by the user, and a pressure

gradient criterion is used if the diameter is less than the diameter

specified by the user.

It is possible to specify the criterion as a global criterion, i.e. it is used for all

pipes to be dimensioned. It is also possible to assign individual criteria to the

pipes.

NetSim uses dimensions from a pipe directory, which ensures that the criterion is

not breached.

There is no limit on how many pipes can be dimensioned, but the number of pipe

types to choose from is limited to 20 different types/dimensions. A name,

internal diameter, roughness and heat loss factor are specified for every pipe

type.

A pipe's diameter is dimensioned if the pipe's diameter is not defined from the

outset. NetSim assigns a diameter to the pipe, which is chosen from the pipe

types in the active directory. If the roughness of the pipe is not defined, the pipe's

roughness is also selected.

The user must be aware that it is possible to define problems relating to pipe

dimensioning which have no hydraulic solution. One example is a looped

system. If the pipe to be dimensioned is part of a loop and two different pressure

gradients are specified, a hydraulic solution does not necessarily exist. In cases

such as this, NetSim will not arrive at a solution and the maximum number of

iterations will be exceeded.

An insoluble dimensioning problem

In the example above, the user has to specify at least one of the dimensions.

Note that there may be combinations of dimensioning criteria, pipe lengths and

reference pressure values in a model which has a hydraulic solution despite

everything. In the example above, a solution can be found if the two pressure

gradients and the two pipes are equal in size.

Dynamic calculations The purpose of the dynamic module is to simulate changes in input temperatures

and loads as a function of time.

By using the dynamic module, the user can study how temperature fronts prepare

themselves in the pipe network as a function of the time.

Water hammer cannot be simulated using the dynamic calculations due to the

time scale for water hammer, normally less than one tenth of a second.

The results are presented in tables, graphs and plots.

Simulation is carried out as a series of stationary calculations separated by a

user-identified time interval where the results of the preceding time step adjusted

by time-dependent factors constitute input data to the next time step calculation.


To change the load in different parts of the network with time, the nodes can be

linked to one of ten potential categories. For every category, the load can be

scaled using a time-dependent factor. The supply temperature, return temperatur

and production price for the production plants can be changed during the

specified time in a similar way.

Steam module The steam module is used like the regular liquid phase module, apart from the

fact that the system requires steam in the supply pipe and liquid phase in the

return pipe.

Latent heat is taken into account when a phase shift takes place in the

heat exchangers.

The compressibility of the steam is integrated into the pressure drop

calculations.

District cooling When the calculation relates to a district cooling network, the physical properties

of the water are adapted to the temperatures used in district cooling networks.

Input and power data is adapted to take into account the fact that energy is

removed at the production plants. When calculating a district cooling network,

the consumers' return temperature must be stated as a parameter, along with

power/flow.

You should be aware that “rules of thumb” from district heating distribution are

not directly applicable. There are small temperature differences, and large water

flows in these networks in relation to power!

What should I do?

Introduction This section of the manual describes how to use NetSim by way of an example

whereby a completely new model will be created. The model will gradually be

supplemented to add functions in NetSim. When you need more detailed

descriptions of functions, menus and forms in NetSim, look up these descriptions

in the relevant sections of the manual.

Start NetSim Start NetSim from the start menu.

Enter your username, password and the name of the database. If you check the

Remember username/password box, your login details will be saved for the next

time you start NetSim.

Doc-To-Help Standard Template What should I do? 11

When you have connected to the database, you can select which model to work

with;

1. Select a model from the drop down menu

2. Click the green arrow to load that model

and when you have done this, content from the NetSim database is loaded.

At the same time, the grid in the model is drawn in the graphic window and the

model data form is completed with data for the model.

If this is the first time you have used the system, there will be no model available

and so you will have to create one. See below.

Pipe types If your NetSim has been converted from an earlier version of NetSim, type data

will already be installed. The same is true if type data was installed when you

installed NetSim. Otherwise you now have to create one or more pipe types to be

linked to pipes in the model before we create the first model in NetSim.

Create a new pipe type

Go to the tab Pipe type and right-click in the grid. From the menu, select Create

new.. The detail form for pipe types now opens. Give your type a name (max. 25

chars recommended), enter the external diameter for the media pipe (mm), the

internal diameter for the media pipe (mm), pipe roughness (mm) and U value

(W/m°C). Note that the U value (thermal coefficient) relates to the individual

media pipe. Indicate that the type is approved for dimensioning. Create the other

pipe types that you need.

Also create a type and name it “?” (without ”) and an internal diameter of 0.00

mm, with pipe roughness 0.05 and thermal conductivity 0.25. We set this type

for pipes that are to be dimensioned.

(At the end of the manual, you will find a suggestion for pipe types, steel and

copper pipes, that you can use as a specimen.)

Create a new model Select in the menu File → Model management → Create new… The calculation

form now opens. It contains a number of preset values which you do not need to

change at this stage. It is possible that you should now select the type of

network, cooling or steam, if it is not a district heating network. Give your model

a name in the model name field, then save your model.

Close the calculation form, and in the model dropdown menu select your new

model.

Creating a grid You now have to create the first pipe in the model. For them to end up in the

“right” place in geographical terms, we will load a map as our background in the

graphic window. Background maps may be in DXF or DWG format.

Background maps can be straightforward basic maps, but they can also be pipe

maps. The important thing is to ensure that the scaling is correct. In NetSim, one

drawing unit is interpreted as meaning 1 m. Retrieve your background map by

going to the Tools tab and selecting Load in the menu backgrounds menu.

When your map has been loaded, select Zoom boundaries in the right-click

menu.Find the right place on the map using Zoom window from the right-click

menu. You can also scroll using the roller on the mouse to zoom in, or use the

zoom tools under the Home ribbon.

It may be wise to purge the background map to remove unnecessary information

before loading it into NetSim.


left-click

left-click

left-click

Create or delete objects

Under the Home ribbon there is a menu called Graphics, in this Menu we find

tools for creating or deleting objects in the map window.

1. Create Pipe

2. Create Node

3. Delete Object

4. Cut Pipe

Create the first pipe

In the right-click menu, or under the Home ribbon, select Draw pipe and left-

click at the point where you want the pipe to start. Move the cursor to where you

want the pipe to go, then left-click at every location where you want the pipe to

change direction. When you arrive at the first branch or dimension change, left-

click to view the coordinates for this point, then right-click to terminate the draw

command and define data for the pipe.

A number of dialog boxes now open which lead you through creation of the

pipe.

The dialog box Spec. start node is opened, and here you can change the

suggested node name if you like (max. 8 characters in the present version).

Select Create node. The dialog box now displays data for the node. Note that the

z coordinate is 0. Change this to the relevant value, then save.

The dialog box containing values for the end node is then opened. Note the z

coordinate, it is copied from the nearest node in the model. Save the node and

close it.

Finally, the dialog box for the pipe is opened (a pipe in NetSim always includes

both a supply pipe and a return pipe). The nodes between which the pipe will be

connected are shown at the top. If you like, you can change the suggested pipe

name (max. 8 characters in the present version). Then select the type of pipe in

the list box. Then select Create pipe. The dialog box now displays data for the

pipe. If necessary, you can change the pipe length and pipe type here for the

supply and return pipe. Select Save to finish creation.

The pipe is ready, and you can now view your pipe in pipe form and the nodes in

node form.

If you select Cancel instead of Save... in the dialog boxes, the object handled by

the dialog box – a start node, end node or pipe – will not be created and the

command will be terminated.

Create the second and subsequent pipes

When the next pipe is to be created and the pipe is to be connected to the

previous pipe, move the cursor towards the circle indicating the node. Start by

right-clicking, then select Draw pipe. Move the cursor towards the node. When

you have contact with the node, this is shown by an indication. IMPORTANT!

You have to left-click to start the draw command while the indication is on. If

the indication is not visible when you start drawing, a new node is created when

you start drawing and you will not get the designated link between the pipes as

intended. You can see this because a new start node is created, not an end node.

If so, cancel this and start again!

Of course, you can both start and end the pipe in an existing node. If you left-

click on a node which indicates that it has been hit and then right-click straight

away, the pipe will be connected to the selected node.

Important: In NetSim versions before 3.0.54, you could create a pipe with a

length of 0 m by right-clicking immediately after starting drawing at the first

pipe. This pipe cannot be calculated! If you have updated from an earlier

version, sort the pipe table according to length in order to locate the pipes with 0

length. Pay attention to the name of the end node (copy it to the clipboard by

pressing Ctrl+C). From the right-click menu, select Delete object. Open the

node table, select the node column, then from the right-click menu select Search,

paste in the node name by pressing Ctrl+V in the search box and the node table

now displayed the node sought. In the right-click menu, select Delete object and

the unwanted node will disappear. We will select this method instead of

selecting the node in the map because this will have exactly the same coordinates

as another node and so it is difficult to select the correct node for deletion!

Cut an existing pipe

The command Cut pipe in the right-click menu, or under the Home ribbon,

divides an existing pipe into two parts, where you point at the pipe and place a

node in the division. The command then continues as a draw command so that

you have the opportunity to directly draw the pipe which connects at the

division. However, you have the option of terminating the pipe both with a new

node and to an existing node or an existing pipe by also dividing that pipe!

Make sure that you have zoomed in sufficiently when you have to select a pipe

or node so that the snap function does not select anything in the background

map.

Delete an object

You are sure to create pipes and nodes that you need to delete!

In map view, right-click and select Delete object, or select delete from the Home

ribbon.

Then point at the object to be deleted. If you point at a pipe, the pipe will

disappear. If you point at a node, the node will disappear in addition to the pipes

starting from the node.

Calculable network

When you have created all pipes in the network and these pipes have been

connected to one another to form a continuous network, it is time to check

whether the network hydraulics are all connected.


Create production plant

Select the node in the network which will include the production plant.

Open the table Production plant, right-click in the empty column at the far left,

then select Create new.

The detail form for production plants now opens.

Give your plant a name.

Enter the supply temperature.

Leave the fields current flow and current power empty.

Place the plant in a node by selecting a node in the list, or select the

“globe” if you have selected the node in the map.

Select Pressurisation return or supply and then enter the static pressure.

The production plant has been defined. Select Save to save it, then close the

form.

Create consumption in the model

Select a node in the network (not the production plant). The node table now

shows the node which you selected. Enter the power [kW] and return

temperature [°C].

Enter calculation conditions

Select in the menu File → Calculation. The calculation form opens. To be able

to perform a calculation, a number of things must be defined in the calculation

form.

There must be a differential pressure in the hydraulic model, i.e. a pressure

difference between the supply pipe and the return pipe. In reality, this differential

pressure is often a long way out into the network. If you have to perform a

calculation for the first time, you can set the differential pressure in the same

node as the production plant. Right-click to the left of Differential pressure and

select Create new. Enter the differential pressure and the node where the

production plant is located.

When a differential pressure has been entered, save it.

The next thing to configure is where the calculations are to be saved. This is

done by clicking on Enter search path in the form. Save it with a relevant name

so that you can find your calculation later.

Notice that the standard file path (after the first calculation) is the last filepath

used, thise means that if you don’t change the filepath between calculations the

last result will be overwritte. If you want to save the results change the filepath!

The calculation has now been configured and basic data has been entered in the

calculation form.

Select Save and Close to finish.

Execute calculation

Identify holes in model

You can now perform a calculation, but before you do this you can see whether

the network is holding together hydraulically and whether there are any “double

nodes”, i.e. two or more nodes which are very close to one another but not linked

together with a pipeline. This is done by selecting Identify holes in model which

can be found under Tools. The results are presented in a graph in NetSim, and

you can quickly see where the error is and correct it.


Make sure that both options are checked in the box. Identify hydraulic networks

checks whether the pipe network is holding together hydraulically and Node on

node checks whether there are nodes on one another or very close to one another

without being connected to pipelines. This distance can be set. Press Esc to

delete the pipe highlights if the network is OK.

Calculate

To perform a calculation, select File Calculation in the menu. Then press the

Calculate button. This generates the input data file for the calculation module.

One box is checked, Display manual settings. Leave this box checked when the

model's calculation properties is unknown.

You can now choose a type of calculation; either a static calculation, with the

data you entered, or a dynamic calculation. A dynamic calculation is a number of

static calculations over a set time and is also known as a time series calculation.

This is described later on in the manual.

Select Start. The calculation begins.

The calculation stops when it is complete, and either it will have continued to the

end or there will be an error somewhere. The Calculation status box tells you

this.

If it is complete, it stops as the stop criterion is smaller than the value you set in

the calculation window. The stop criterion is 0.005 by default. In this case, the

result is less than 0.005

The number of calculations or iterations can also be seen, in this case 25.

If the calculation is not complete, the Calculation status box tells you this, and if

you click on the Chk button you can open the error message in a text editor in

order to analyse the error.

The results of the calculation can be viewed by clicking on the Out button. See

later on in the section on Results analysis.

Troubleshoot model

If the calculation is not complete, the Calculation status box indicates this, and if

you click on the Chk button you can open the error message in a text editor in

order to analyse the error.

For some types of error, row numbers in the netsim file where the calculation

module has encountered problems are written to the Chk file.

Open the calculation file and review the rows excluded.

There is a list of error messages at the end of the manual. You can see here what

an error message means.

Fault-free model

The model now functions hydraulically, it hangs together. In the next element

we will specify the actual consumptions and production plants that must be in

the network.

Sectioning option

If you shut down both the supply pipe and the return pipe, you will force the

water to take a different route if there is a loop feed option. Otherwise a larger or


a smaller area will be shut down. How large this area is, along with which parts

are affected by the shutdown can be displayed graphically in the function

Sectioning option.

Under the Pipe tab, select the pipe that you want to shut down. It is easiest to

click on the pipe in the map, and thus display the pipe in the table. In the grid, go

to the column Closeoff status. Close both the supply pipe and the return pipe by

selecting Fully closed. Do not forget to save by right-clicking and selecting

Save.

When the pipe is closed, an area is closed off.

Select Tools Notification. The box below is displayed.

The pressureless parts of in the network are displayed in black.

You select the part which is pressureless, and the customers affected are

exported to a text file which can be linked to a Word document, for example.

Print. Post. Done! The customer has now been advised of a planned shutdown!

Split model

If you want to divide a model, e.g. to delete a town district, this is easy to do

using the function Divide model.

Start by copying the model that you want to divide. Then shut pipes so that two

hydraulic networks are created. Both the supply pipe and the return pipe have to

be shut down.

The pipe is shut down. Select Tools Split model. A confirmation request is

displayed.


The “green network” is selected and so must be retained.

Only the network below is left.

The model now functions hydraulically, it hangs together. In the next element,

we will specify the parameters that have to be met to allow a calculation to be

performed: A production plant with pressurisation, a differential pressure, a

consumption or flow and the return temperature in a node.

Supplement the model with consumption/customers

Create a customer via a customer data form.

A calculation can take place if there is at least one consumption in a model. This

consumption is in a node. Consumption can either be linked to a customer or be

entered directly for the node.

If consumption is entered directly for the node, power or flow must be specified.

Import customer from external file

The format for the import of customer data is described in the manual section

entitled Consumption data. One very easy way in which you can create a

template for import is to create a “sample customer” in NetSim and then export

this customer to a text file!

Open a model in NetSim. There must be at least one node in the model!

Go to the Customer tab.

In the right-click menu, select Create new

Now enter values in the fields which you can easily recognised in the

exported customer data file.

In the menu, select File -> Customer data -> Export of customer data.

Open the exported file in Notes, select the row and paste the row into

Excel.

ANLID¤KUNDID¤KUNDNAMN¤FASTIGHETSBETECKNING¤ADRESS¤N766¤N766¤N766¤1¤16¤1¤31¤2300¤2012¤100¤1¤230¤0¤4497¤0¤45¤50¤0¤0¤¤¤¤¤¤

The file looks like the one above (wrapped). If you want to include

notification information, this is added between the last four field

separators.


Column-separate the file in Excel, the ¤ character is the separator.

Now create new rows in the Excel file for your customers. Use your

sample customer as a template. When you have finished, delete the

sample customer. Then set national settings use the ¤ character as a

column separator, or replace your separator with ¤ via a search and

replace command in notepad. Note that numerical values must be

integers with no decimal places. Save the spreadsheet in CSV format.

Import the file by selecting the menu File-> Consumers -> Import all

Your consumers are loaded!

Several production plants

Production plants

When a plant has been defined in a model, one or more other plants can be added

in the same way using the command Create new.

Power or flow must be specified for all production plants except for one.

The supply temperature must be specified for all plants, and only one plant's

pressurization must be activated.

If the network consists of several separated networks, the above is applicable for

each network.

Position a heat exchanger

A heat exchanger placed in a pipe can be used to supply energy to or remove

energy from a pipe. For a more detailed description of this, see section Heat

exchanger form.

Pressure regulations

Define a pressure increase station

A pressure increase station is a pump station where a pressure change takes

place. This pressure change can be at the supply pipe or the return pipe or at both

pipes. For a more detailed description of this, see Pump form.

Define a pressure reduction

A pressure reduction is a change in pressure in a pipe, a valve in the pipe

affecting the pressure. This valve can be placed in either the supply pipe or the

return pipe. For a more detailed description of this, see Valve form elsewhere in

the manual.


Analyse calculation results

Summary calculation results

Calculation results are displayed in NetSim Analyse. The tab Overview shows a

summary from the simulation. The file simulation-name.OUT holds all values

applicable to the calculation an can be opened in any text editor.

It is possible to search where these values are using a search function, either

directly in the map or in the node or pipe table.

The power balance for the production plants is displayed a little further up in the

tab Out.

Pipes dimensioned by NetSim are displayed under the header Pipe Dimensioned.

Map plots

It is possible to print the map from Analyse. The printout is defined in File

Print

Graphs

Graphs are described under Diagrams in the section on Analyse.

Table data

The node and pipe tables show calculation results in tabular form. Take care to

make sure that the values are reasonable.

NetSim system summary Vitec Release Manager

Vitec Release Manager is an application that maintains your NetSim

installation. The application manages most of the installation and checks that

you are using the latest version of NetSim. When later versions of Vitec are

published, it automatically downloads the new version and installs it.

Release Manager indicates the

versions of installed products, and

if a later version has been

assigned to the Vitec installation

this version is displayed and the

product is flagged up with a

different colour in Release Manager. In this case, click on the info button to fix

the product.

Here, you can download any updated

using the Download button. That is to

say, there are no automatic updates; you

have to enable the download and update

yourself. You have to be authorised to

download updated via the Internet and

to change the content of your NetSim

installation for this to work! NetSim and

Analyse are copy-deploy installations.

This means that everything you need to

make the programs work, except for the

Oracle client and .Net, is collected in the program folders for the relevant

programs. If downloading is not permitted, the update can be copied to your

computer from a medium created from a computer where downloading is

permitted.

Modelling

NetSim version 3 is the graphic tool for managing your calculation models in the

NetSim model database. Below is a description of the menus and forms which

you will find in NetSim 3. Some forms with a central function, e.g. the

calculation form, are described in detail, while other forms of more “peripheral”

significance are described in more general terms. In general:

forms and windows include a right-click menu with functions.

double-clicking in the leftmost column of the grid forms opens detailed

forms for the record if there are any detailed forms for the grid form.

forms and toolboxes can be positioned in any location by the user.

changing data can be undone

copying (Ctrl+C/Ctrl+V) between cells in the forms is permitted if the

value pasted in is copied from the same column.

if multiple users are logged on to the same database simultaneously, the

last value saved is valid.


Calculation. The calculation module in NetSim is started directly from the menu

under Modules, automatically by NetSim when data is exported from the form

Calculation to the calculation module, or directly from the explorer by enabling

a calculation file from NetSim.

You can reach associated calculation results directly from the calculation

module.

Results anaysis The calculation results are analysed in NetSim Analyse. Analyse is an

independent product which displays the calculation results as maps, diagrams

and tables divided into levels.

Analyse is started directly from the Home Ribbon.

As in NetSim, you can use external DWG/DXF files as backgrounds and plot

and save in DWG/DXF and raster format.

Doc-To-Help Standard Template Modelling 29

Modelling

User interface

The NetSim program window includes the above blocks in the basic configuration. A graphic window in

which the network map is displayed, a menu, a list of toolboxes, a form with tabs which contain model data,

a form with tabs which contain system data, and right-click menus. You have plenty of freedom to move the

blocks, create separate blocks, dock and lock and hide blocks, change the order of columns, etc. as you

wish. Strictly speaking, only the menu, map window and status list are fixed. You can always return the

appearance to its original mode by selecting a command under Help in the File menu. Take the opportunity

to adapt the appearance so that it suits you best! It is a good idea to create your own “toolbox” in which you

have your own shortcuts to the most common commands; see the paragraph describing Graphic window for

more details.

General information on forms The primary way in which you can access the data in the NetSim database is via a grid form in which the

data for an object is displayed in columns. Pipes are displayed by way of example here. The grid shows all

pipes in the model. When you select a pipe in the map screen, this pipe is highlighted in the grid, and the

highlighted pipe in the grid is also highlighted in the map screen.

The fields which provide “primary information” on the pipe are displayed in the grids. Start and end node,

pipe type, etc. All data on a pipe can be accessed in a detailed form. The detailed form is opened if you

double-click in the column at the far left. The values listed from another table, e.g. pipe type, are selected

from drop-down lists. Double-clicking in the column header sorts the form according to the highlighted

column.

There are more options in the right-click menu. Search and filter,

delete objects and export to Excel.

You can generally select a number of fields in a column and paste a

value into the highlighted fields.

Detailed form for pipe. You can access all data applicable to the pipe here!

If you select a value from a drop-down list, you can restore the field to an “empty field” by selecting the

“empty” value in the list or deleting the content in that field.

Graphic window The graphic window in NetSim is a CAD component which shows the pipe network in the selected model

with the correct coordinates. The coordinate system is an arbitrary orthogonal system where the y-axis is of

north and x-axis is of east.


You can use map files, schedules, etc. in DWG/DXF format as backgrounds to the pipe network. These

backgrounds may also include graphics as orthophotos.

You can create pipes in and delete them in the graphic window. Points and opens the forms in the database.

You can save the network image from the graphic window in DWG/DXF + a number of raster formats and

print out all or parts of the network to an optional scale.

You can use the layer properties manager under Color tab under the tools ribbon in the menu to select

colours and line widths in the map screen for the best display of the pipe network.

File menu

Model Management

Create new...

This function creates a new model in the database. The Calculation opens with a

number of preset values for the model. Give the model a name in the field Model

name. Then save the model using the Create function in the form. You can now

select the model as your current model in the model selector.

Copy...

This function allows you to make an identical copy of your current model. A

dialog box opens in which you give this copy a name. In the copy, you can

change most things in relation to the master without changing the master. See

section Model management

Delete...

You can use this function to delete your current model from the model database.

A dialog box opens where you can select whether you want to delete the model

or cancel the function.

Import

The Import calculation file function allows you to import a calculation file (see

section Calculation module's input data file). The file can be a “complete”

calculatable calculation file or a file just containing definitions of the geometry

for the model, e.g. manufactured from a CAD file or exported from a network

information system. The import adds information to the model and does not

need to be a complete model. You must observe what names pipes and nodes

have in the import file in relation to which names you use for pipes and nodes in

the model database to which you are importing. If nodes/pipes exist with the

same names in the import file and the database, the node in the database receives

the coordinates which it has in the import file. Likewise, the pipe in the database

is given the geometry which it has in the import file.

An import file cannot fully build up all boundary conditions in the model

database. For e.g. pumps, any reference value to which the pump is regulated

cannot be set up by the import function. This has to be added manually to the

model after importing.

Calculation...

The calculation is configured and enabled in the calculation form.


Load factor: A given value in node, flow or power is multiplied by

the factor in the input data for the calculation module.

Δt factor: A given value in node for cooling is multiplied by the

factor in the input data for the calculation module.

Return temp. factor: A given value in node for return temperature is

multiplied by the factor in the input data for the

calculation module.

Heat loss factor: A given value for the pipe types' heat loss factor

(W/m°C) is multiplied by the factor in the input data

for the calculation module.

Network level: Enter 1, 2 or 3 for calculation of all pipes in

the model, distribution and main pipes or just main

pipes.

Ambient temp.: The global ambient temperature against which the

heat losses of all pipes are calculated, except for the

pipes which have a local ambient temperature

specified.

Model type: Planned or normal.

Pipe diam.: (mm) Included in the dimensioning criteria; see below

Velocity: (m/s) Included in the dimensioning criteria; see below

Gradient: (Pa/m) Included in the dimensioning criteria; see

below

Default pipe type: Included in the dimensioning criteria; see below

Dimensioning criteria: Pipes with an unknown internal diameter are

dimensioned as follows: The program makes a

selection from pipe types which are approved for use

for dimensioning a pipe type which provides the

highest stated velocity. If the internal diameter of this

selected pipe type exceeds the value given for

diameter, a pipe type which gives the highest stated

pressure drop gradient is selected instead. If all the

pipes in a ring connection are to be dimensioned, the

program uses the type specified as the default for one

of the pipes in the ring connection. Pipe type ? must

not be included in the list.

Pressure loss factor 1: Calibration factor for pressure drop calculation; see

below.

Pressure loss factor 2: Calibration factor for pressure drop calculation; see

below.

Pressure drop calibration

The calculated pressure drop in the pipe × with factor

1 with the addition of the calculated pressure drop ×

factor 2 × the internal diameter of the pipe is reported

as a pressure drop in a pipe. The defaults are 1 and 0.

Common values for factor 1 are in the range 1.05 –

1.1.

Differential pressure, node: In the specified node, the pressure difference

between the supply pipe and the return pipe must be

the stated value. A differential pressure and node

must be specified for every separate hydraulic

network in the model.

Headers 1, 2 and 3: These texts pass out in input data to the calculation

module and on to the results files.

Steam system, Annual run: Select whether the model relates to a network for

steam and condensate, a district cooling network, if

the calculation is to be executed as an annual run, or

if only the supply pipe is to be calculated.

Outdoor temp.: Enter the outdoor temperature for which factors for

power, cooling and return temperature are to be

calculated when updating nodes from customer data.

This value is also used when determining the supply

pipe temperature from the production plants.

Method: Select which value is to be used when updating nodes

from customer data.

Network level: Select the customer levels – service, distribution or

main pipe level – to which the customer's data is to be

written when updating nodes from customer data.

Return temp./Δt: Select which is the values is to be used when updating

nodes from customer data.

Update nodes: Execute summing of power/flow, return temp./Δt

from customer data to nodes. NB If you change level,

first “clean” node data (Tools → General updating).

Bypass: Execute summing of bypasses from customer data to


nodes.

Stop criterion: Calculation continues until the difference in pressure

between two iterations is less than this value,

normally 0.005. If the calculation fails to find a

solution before the maximum number of iterations

has been exceeded, this is changed to the value which

the calculation module has reached. If the value does

not exceed 0.09, the result is generally adequate.

Relaxation: The value by which the calculation module has to

adjust input data for the next iteration. Normal value

0.5. If the calculation module does not reach a

solution, change this value to 0.8 or 0.9.

Enter search path: This field displays the search path and filename for

the latest calculation file. Click to change / filename.

Version The value is 1 or 2. This value affects a method used

during the simulation. Standard value is 1. Change the

value to 2 if the simulation does not converge to the

stopping criteria.

Display manual settings: If this is selected, calculation does not start

automatically when the input data file for the

calculation module is complete, but is displayed only

[by the calculation module dialog for selection of a

calculation type when the input data file is complete.

Calculate: An input data file is generated for the calculation

module, and depending on setting (above), the

calculation module is started.

Comment: A “plain text field”. Use this field to document

valid calibration factors, etc.

Save: Use this function to save current settings in the form.

Exit: Closes the form without a save function.

Consumers

You can use the functions under customer data to import and remove

information on consumers (consumption data) in the model. The format of the

import file is described in the section entitled Consumption data.

Consumer data is organized into three information categories.

General information, IDs, names, addresses, etc.

Consumption information, power, energy, cooling, etc.

Node references, the node in the model in question to which the

customer is related at the relevant level (service, distribution, main

pipe)

The details in the general category are the same for all models where the

customer is used, while the details in the other categories are specific to every

model.

Import new only...

This function opens a file opening dialog box where you select which customer

data file is to be imported. This function creates, in the model, the customers in

the customer data file which are not included in the model. Customers in the

customer data file which already exist in the model are not affected.

Import all...

This function opens a file opening dialog box where you select which customer

data file is to be imported. This function creates, in the model, the customers in

the customer data file which are not included in the model and replaces

information for all customers which exist in the customer data file and in the

model with information from the customer data file. Customers which exist in

the model but not in the customer data file are not affected.

Copy customers...

This function copies customer data between models in the database. This

function opens a dialog box where you select the model from which you have to

copy data to the current model. You select whether all data on the customer is to

be copied, i.e. if consumption and coupling to nodes are to be copied or if just

consumption data is to be copied (see the section entitled Consumption data).

Delete customers...

This function is used to delete all customer data from the current model.

Customer information for other models is not affected by the function.

Export customer data

This function is used to write data for all customers in the model to a text file.

This text file is formatted as an import file for customers, see the section entitled

Consumption data.

Save as...

You can save the model to a file in a range of vector and raster formats such as

DWG, DXF, DGN, JPG, TIFF and PDF.


Print..

This function opens the print manager. You can select a printer, paper format,

print scale, print range, etc.

Exit NetSim

This function closes NetSim.

Options

The size of the zoom box (metres) controls how large an areas is to be displayed

in the graphic window when you zoom into nodes and pipes.

The sizes of nodes and other items are also set here. If you have problems with

snapping to nodes, you can make the setting a little larger (perhaps 2 %).

You can set at which zoom level nodes are shown. Try out what seems

reasonable… 200 or 2000, perhaps.

Autozoom according to the highlight. Select this if you want to zoom directly

into a node or pipe as soon as you have highlighted it in the grids. This is an

effective tool in combination with an appropriate zoom box size.

Language. Swedish is the default, but you can switch to English.

An Analyse search path is specified here. The search path under which Analyse

is normally installed is preset.

Help

Online manual opens the manual in the browser.

Team Viewer. Starts online support with Vitec Energy. Contact one of the Vitec

Energy consultants and agree on a time so that they can provide you with

instruction or control your NetSim remotely. You submit your ID and password

as shown in the dialog box. An Internet connection is required!

About Vitec NetSim shows the versions of the modules installed in NetSim.

Reset docking windowresets the configuration to the default setting defined on at

delivery. If you have “undone” the Pipe type directory, for example, you can

easily redock it using this function. Note that language settings also are restored

to initial value.

Home Tab

Zoom

Window

A classic function where you can zoom into part of the network.

To Extent

A function which ensures that the entire network is visible. It may be useful to

use this if you want to return to a kind of “start level” if you have zoomed in.

To node

If you have selected a node in the node list, you can select Zoom node in order to

centre it in the map and zoom in on the node.

To pipe

If you have selected a pipe in the pipe list, you can select Zoom pipe in order to

centre it in the map and zoom in on the pipe.

Previous

You can use Zoom previous to go back one step at a time to the zoomed-in

“screen” which you saw previously. You can go back several steps.

Pan

You can use Pan to take hold of the entire map by holding down the left mouse

button, and you can then drag it in any direction without changing the degree of

zoom. You can exit this command by pressing Esc or clicking on the command

again.

Modules

Calculator


This allows you to open the NetSim3 Calculator separately. The main use for

this is to open calculations files sent from another database or with manual

changes done after the .netsim file has been created

Calculation

Starts the calculation module's settings form with the last model calculated

preselected. You have the option of choosing another file or calculation type or

opening the control files created by the calculation module.

Analyse

Starts Analyse with the last calculation data.

Data management

Show selection

If you have selected an area or selected pipes and nodes, you can select Filter in

grid and so view them in the node list or pipe list. E.g. you can then choose to

export to Excel. Note that you have to create two exports, one for the node list

and one for the pipe list.

Note that nodes can be filtered out only when you have zoomed into the map

sufficiently.

Show on map

When you select one or more nodes and/or pipes in the grids, you can see where

they are in the map. Select Show selections on the map when you have finished

making your selections in the node and pipe grids. You can select more if you

hold down Ctrl while left-clicking at the same time.

Show level division

You can use Show level division to see in the map which pipes are classified as

main pipes, distribution pipes and services. These are displayed with different

colours in the map. You can easily see whether you have classified the pipes

wrongly.

Tools Tab

Backgrounds

Load

This function allows you to add one or more maps as backgrounds in the graphic

window. Purge the background map beforehand if you are using a heavy file.

Delete

This function allows you to delete background maps from the graphic window.

A dialog box shows the maps added as backgrounds, and you select the ones

which are to be deleted.

Color

Background

Opens a dialog box where you select a background colour for the graphic

window.

Layers

Opens the setting dialog box for layers in the graphic window. Here, you can

influence which colours and line widths which NetSim uses for pipes and nodes

and flags.

Here, you can also influence presentation of the backgrounds which you

imported into NetSim.

Layers also lets you show or hide the different text options shown below.

Text

A function in NetSim involves now placing text on nodes and pipes. When you

have selected the items for which you want text, you edit the text style, size and

colour in order to view this in NetSim.

Under Style Name, select the various layers for which you want text. Set the

Font, height, etc.

To show or hide text go to the Layers settings.


Calculation Tools

Notifications

See the text on Sectioning option earlier on in this manual. There is an option to

shut down an area here.

Calculate Net Levels

You can use this function to determine which pipes are to be classified as service

pipes.

Before this takes place, you have to have decided which pipes are to be main

pipes, level 3. This is most important if you have pipes with smaller dimensions

which are main pipes.

Select Display to view the classification of pipes in the map. Change this

classification if you like. Select Run if you want to apply Max. internal diameter

AND Length of the pipe network.

As far as calculations are concerned, you can execute faster calculations for just

main pipes if you have a large pipe network with lots of ring feeds. In this case,

move the customer power to the main pipe beforehand.

Trim Model

This function reduces the number of pipes with similar properties in a model.

Set the lengths and the differences in internal diameter and thermal conductivity

which are to apply to the pipes. Then press Prepare followed by Run.

This can be done several times as it only checks two pipes at a time.

Report

Select the report to be run for the current model.

The report's results are displayed in a grid which you can export to Excel or copy

to the clipboard.

Reports in the present version are:

Production plant Summary of total production and total defined

consumption in the model.

Key Numbers Summary of technical key figures for the model.

Status This report shows all steering parameters for

the model, production, pumping, reference values,

etc.

Summarize Pipes This report sums all lengths, grouped by dimension

(pipe type)

Price This report sums all lengths and costs,

grouped by price category.

Comments This report shows all comments made for objects in

the database.

Model data forms The model forms consist of a grid form which shows primary data for the object

type (see the section entitled Model concepts). A detailed form showing all data


on the object is opened if you double-click in the row number column to the left

of the grid form.

The grid forms have a right-click menu containing functions for the form, e.g.

save, undo and delete. The grid forms can be filtered, sorted and exported to

Excel.

The model data forms are:

Node grid, detail

Pipe grid, detail

Production plant grid, detail

Pump grid, detail

Valve grid, detail

Heat exchanger grid, detail

Accumulator grid, detail

Customer grid, detail (only when creating a new customer)

Annual data grid, detail

Node form

The grid form for nodes shows all nodes in the model. Here, you can switch the

name of the node, enter powers/temperatures, etc. The node highlighted in the

form is indicated in the map screen. The node form is also displayed with a node

highlighted when you highlight a node in the map.

The map screen includes the command Zoom node which centres the map screen

over the highlighted node in the grid form. Besides the general functions, the

right-click menu in the form includes the command Display customers which

opens the customer form filtered using the highlighted node name.

Double-clicking in the row number column opens the detailed form for the

selected node. This detailed form displays all information which can be given to

a node.


Pipe form

The grid form for pipes shows all pipes in the model. Here, you can change the

name of a pipe, change the start and end nodes of a pipe, select a pipe type,

change the length and open/close pipes. The pipe highlighted in the form is

indicated in the map screen. The pipe form is also displayed with a pipe

highlighted when you highlight a pipe in the map.

The menu includes the command Zoom pipe which centres the map screen over

the highlighted pipe in the grid form.

Double-clicking in the row

number column opens the

detailed form for the selected

pipe. This detailed form

displays all information which

can be given to a pipe.

Level: the pipe can belong to

service (1), distribution (2) or

main pipe (3) level. Levels

must be selected so that 3 must

form a coherent hydraulic

network, level 3 + level 2 must

form a coherent hydraulic

network, level 3 + level 2 +

level 1 must form a

hydraulically coherent

network. (see production

plant form and menu

Calculation).

Local dimensioning criterion:

for every pipe to be

dimensioned, a local

dimensioning criterion can be specified which replaces the global dimensioning

criterion (see Calculation menu). Select whether this criterion is to be applied to

the supply pipe, the return pipe or both pipes, as well as values for velocity,

gradient and max. diameter (see also the keyword *LDIM).

Optional: the pipe is not included in reports for length and volume.

Production plant form

The grid form for production plants shows all production plants in the model.

You can enter production, temperatures and network pressurisation here. The

node in which the plant is located is highlighted in the map screen when you

highlight the plant in the grid form. The detailed form for the plants is opened if

you double-click in the row number column at the far left.

To create a new plant in the model, select Create new in the right-click menu.

This opens a detailed form.

Give the plant a name

or select an existing

plant from the list at

the top right. Connect

the plant to a node, the

icon to the near right of

the field retrieves the

node highlighted in the

map. The adjacent icon

shows the selected

node in the map. You

should place the plant

at the end of an

“appendix pipe”. No

other values, i.e.

powers, temperatures,

shunts or bypasses, are

to be specified in the

node in which where

you place the plant!

Enter either power or flow, enter supply pipe temperature. Enter a pump type

and pressurisation of the network, where necessary. The fields max. and min.

power are only information you provide so as not to define the plant outside its

working range. In the model, there but be one and only one plant for every

separate hydraulic circuit without a specified power or flow. Likewise, in a

model for every separate hydraulic circuit there must be one and only one plant

with data for pressurisation of the model (static pressure). It is possible in the

grid form to link a temperature curve to the plant (see section Temperature

curves under System data form).


Pump form

The grid form for pumps includes all pumps in the model. In this form, you have

a direct overview of how the pumps are set in the model. In the map screen,

select the pipe in which the pump is located when you highlight the pump in the

grid form. The data which you enter for a pump relates only to the current

model. Thus the same pump can be used in several models with different

settings!

Some of the columns include “drop-down” icons which are disabled. These

values can be changed instead in the pump's detailed form which you open by

double-clicking in the row number column at the far left.

To create a new pump, select Create new in the right-click menu.

Give the pump a name or select an

existing pump from the list at the top

right. If a pump type is to be entered,

select the type from the list. The pump

belongs to the pipe and can relate to a

pressure change in the supply pipe,

the return pipe and both the supply

pipe and the return pipe. Therefore,

you must enter values for both the

supply pipe and the return pipe.

This pump lifts both in the supply and

the return pipe, The pump's lift is

unknown, and therefore the fields in

head supply and head return is empty.

The pump is controlled to maintain a

150 kPa differential pressure in node

S3 (select type of reference value).

Quota S/R is set to 70% which means

that 70% of the total lift is taken in the

supply pipe and 30% in the return

pipe. The pump is located in pipe F4-

F5, adjacent to node F4. The icon at the near right of the pipe name field is used

to retrieve the pipe which you have highlighted in the map screen, while the icon

to the right of this indicates in the map screen the pipe you selected. The icon to

the right of the reference value node also retrieves the node which you highlight

in the map and the icon to the right of this indicates in the map the node you

selected. Max. pump lift and mass flow are items of information sent to the

pump control function in Analyse. These values do not restrict the work of the

pump in the calculation, but in Analyse they provide information on whether the

pump is operating beyond its actual capacity.

If the pump lift is determined, you cannot give a reference value. In this instance,

enter no setpoints as the reference value type. If you select a pump type and enter

a speed, the pump lift is determined via the characteristic for the pump type. In

this case, the field for lift must be empty and the reference value type must be no

reference values. See also the section Pressure regulations – pumps and valves.

Although in many cases it is valid, it is in most cases preferable to locate the

pump next to node 1 in the pipe. Further, if a pump lift is defined in both the

supply and return of a pipe, pumping may not be placed in adjacent pipes.

Valve form

The grid form for valves includes all valves (for pressure regulation) in the

model. Here, you have a direct overview of how the valves are set in the model.

In the map screen, the pipe in which the valve is located is highlighted when you

highlight the valve in the grid form. If you double-click in the row number

column, the detailed form for the highlighted valve is opened.

To create a new valve, right-click in the grid form and select Create new.

This opens a detailed form where you define the function of the valve.

Give the valve a name or select

an existing valve from the list

at the top right. This valve has

a type linked to it (V100) and

an opening degree (15° from

closed) is set. The reference

value type must therefore be

set to no setpoints . The valve

is located in pipe A1215 in the

return pipe adjacent to node

F995, and therefore the field

for fixed pressure reduction in

supply pipe is empty, and for

the supply pipe the fixed

pressure reduction is set to 0

(kPa). When a fixed pressure

reduction or an opening degree

has been entered, you cannot

use a reference value. In the

same way as for pump (see

above), the icons adjacent to

pipe name and node name can help you to position the valve in the model. The

values which you enter for a valve relate only to the current model. Thus the

same valve can be used in several models with different settings! See also the

section Pressure regulations – pumps and valves.


Heat exchanger form

Heat exchangers are placed in pipes. The heat exchanger is used to supply

energy to or remove energy from the water which flows into the pipe. To create a

new heat exchanger, right-click in the grid form and select Create new. A

detailed form opens in which you can define the exchanger. The data which you

enter for the exchanger is

valid only for the current

model. Thus the same

exchanger can be used in

several models with

different data!

Give the heat exchanger a

name or select an existing

exchanger from the list at

the top right. The power

(kW) of a heat exchanger is

specified with a basic

power (kW) + a

temperature-dependent

component kW/°C where

the temperature relates to

the temperature of

incoming water in the

exchanger. Negative power

means that energy is

removed from the water (temperature reduction), while positive power means

that energy is added to the water in the pipe. This exchanger supplies energy

with an power of 4000 kW, regardless of the incoming water temperature, is

located in the return in pipe A1102 adjacent to node F899.

Accumulator form

You create a new accumulator by selecting Create new in the right-click menu.

Give the accumulator a name or select an existing one from the list at the top

right in the form.

Specify the node in which the accumulator is to be located. As for production

plants, the accumulator should be placed at the end of an “appendix pipe”, and

there must be no other values such as power/temperatures/bypasses, etc. in the

node. The icon to the left of the node field retrieves the name for the highlighted

node in the map. The icon to the right of this shows the selected node in the map.

Volume (m3): The accumulator's active volume.

Nom. power [kW Nominal power consumption. If this the value is left

undetermined, the power balance in the network

determines whether the accumulator is loaded or

emptied. (N.B. the powers of all production plants

must then be specified.) If a value is specified (with

characters), the accumulator works with this value

during the calculation (N.B. a production plant in the

model must have an undetermined power). A positive

given power acts like the accumulator is storing,

while a negative power acts like the accumulator is

unloading energy.

Thermal coeff. (kW/°C): Heat loss factor which, when multiplied by the

difference between the accumulator's average

temperature and the ambient temperature, gives the

accumulator's heat loss power in kW.

Ambient temp. (°C): The ambient temperature against which the

accumulator's

heat losses are calculated.

Min. temp. (°C): Minimum temperature in the accumulator at the start

of the

calculation.

Max. temp. (°C): Maximum temperature in the accumulator at the start

of the

calculation.

Average temp.: (°C): Initial average temperature in the accumulator at the

start of the calculation.


Customer form

The grid form for customers differs from other grid forms insofar as all data for

the customer is displayed in the grids. This is mainly out of consideration for

exporting to Excel.

When you create a new customer, first select the which is the customer's level 1

placement. In the customer form, then select Create new. This opens a detailed

form with which you create the customer.

Enter a facility_ID, enter a value in at least one of the fields customer ID,

customer, property designation or address.

Enter a relevant category figure (h)

Click on the icon at the near left of the node level 1 field to retrieved the

highlighted node's name for node levels 1, 2 and 3.

Enter values in the fields for power, consumption, cooling and return

temperature. Type 0 (zero) in the fields for which you do not enter values. Select

a customer type for power, cooling and return temperature. Then save the

customer. You can then edit all data for the customer in the grid form.

System data forms System data is data which is not model-specific but general for all models in the

entire installation. Pipe types are one example. The system data forms are

structured in the same way as the model data forms, with a grid which shows

primary data and a detailed form containing all information for the record.

The various types are:

Pipe type grid, detail

Pump type grid, detail

Valve type grid, detail

Customer type grid, detail

Temperature curves grid, detail

Node type/time series grid, detail

In general, you can create a new pipe type, pump, etc. by right-clicking and

selecting Create new in the number column for the type that you want to create.

Pipe types

As a minimum, enter a name (max. 25 chars recommended, must NOT include

blanks), internal diameter (mm), roughness index (mm) and thermal conductivity

(U value, W/m°C) for the pipe type.

If the type has to be

accessible for

dimensioning pipes,

you must select

this. A maximum of

20 pipe types can

be selected for

dimensioning. An

internal diameter of

0 mm signals to the

calculation module

that the pipe has to

be dimensioned!

Create a pipe type

with a name ?

which has an

internal diameter of

0.00, etc. This

allows you to see more clearly which pipes are to be dimensioned.

You can provide further information on the type which describes the type in

more detail, e.g. material, make, etc. The price categories are utilised by the

price report, the pipe's price category being specified with a value of 1 to 6 and

the price being retrieved from the pipe type's corresponding value.


Pump type

The pump characteristic is

defined for a pump type in

this form, which can then

be used for one or more

pump facilities. Enter the

name of the pump type

(max. 8 chars), the speed

(revs per second) for which

the characteristic is

defined. Then enter

corresponding values for

flow (kg/s), pump lift (kPa)

and pump power (kW) in

ascending order with

regard to flow. Up to 12 points can be entered in the characteristic. “Close” the

curve at both ends, i.e. enter values for flow 0 kg/s and lift 0 kPa.

You can provide further details for descriptive information on the pump type,

e.g. make and model type.

The fields max. speed (revs per second), - power [kW and –current (A). Voltage

(V) and rated power (kW) are values sent to the Pump control function in

Analyse.

These values do not restrict the function of the pump in the calculation, but in

Analyse they signal whether the pump is operating beyond its actual capacity

range.

Valve type

The characteristic for a

valve type is defined in

the form. The

characteristic is specified

as an opening degree 0 –

90° from fully closed and

corresponding capacity

value Kv (tonnes/h)/bar½).

I.e. 0° indicates a fully

closed valve and 90° a

fully open valve. The

characteristic can be

specified using up to 10

points. When a valve type

is linked to a valve, you

specify the current opening degree for the valve; and the pressure drop across the

valve is then calculated on the basis of the given characteristic.

You can provide further details for descriptive information on the valve type,

e.g. make and model type.

Customer type

A type for power, return temperature and cooling as a function of outdoor

temperature must be related to all customers.

The grid form shows the type name and the ID of the type in the database. N.B

The type ID must be specified in the import file for customers! If the import file

contains types which do not exist in the database, these types are created in the

database with a linear function which you can adapt to the required appearance

after import. Up to 99 different type curves can be specified in the database.

In ascending order with regard to outdoor temperature, enter the factor by which

the customer's power, return temperature and cooling is to be multiplied in order

to adapt the value to a given outdoor temperature (load case). The calculation

form specifies an outdoor temperature for the load case, and use the curves

above to sum customers' power/cooling/return temperature to the nodes.


Temperature curves

You can define the temperature programs for production plants here.

In ascending order, enter the outdoor temperature and, for the outdoor

temperature, the corresponding supply pipe temperature.

In the Production plants form, select which temperature curve is to be used for

the plant. When load cases are specified in the calculation form, a function

retrieves a supply pipe temperature for the load case from the specified curve.

Node type/time series

Nodes in NetSim are divided into up to 10 different types. Each type can be

controlled individually in a dynamic calculation with regard to flow, power and

supply pipe temperature. Typically, all nodes are assigned type 1; apart from

production plants, which are given individual types. Furthermore, individual

nodes with deviating consumption patterns can be assigned a separate type if

necessary. A time (decimal hour) and corresponding factor are specified for

every type of value

Enter the “breakpoints” in the time series In the calculation, values for

intermediate times are interpolated from the given values.

Calculation

The calculation module in NetSim is started directly from the menu under

Modules, automatically by NetSim when data is exported from the form

Calculation to the calculation module, or directly from the explorer by enabling

a calculation file from NetSim.

Model file: this field displays the file selected for calculation: You can use the

file selector on the right to select a file for calculation, and use the adjacent

review icon to open the file in Notes for review/editing (see the section entitled

Calculation module, input data file).

Results directory: the directory where the results from the calculation are saved.

Calculation type: You can switch the calculation type between stationary and

dynamic calculation. If you select dynamic calculation, you have to select a time

series file using the file selector on the right. You can also open the time series

file in Notes using the icon at the far right.

Time series calculation: In the case of dynamic calculation, you have to enter a

start time, time step length and number of time steps (see the section entitled

Dynamic simulation).

Calculation status: The calculation status shows the progress of the calculation.

Doc-To-Help Standard Template Calculation 57

Result: You can use the icons on the right to open the text-based results file

(.OUT), the control file (.CHK) which shows any errors in input data, and the

file containing selected dimensions for pipes which are to be dimensioned

(.PTY).

You can use soft and quick stop functions to cancel simulation in progress with

or without printing the results. You use these functions in cases in which

simulation does not appear to converge.

File types

Input data for the calculation module is:

Simulation_name.netsim Keyword.

Simulation_name.lmt XML file. Limits for pumps.

Simulation_name.cf1 Time series for dynamic calculation.

Results files from the calculation module are:

Simulation_name.out results printout in text format.

Simulation_name.xml results summary in XML format.

Simulation_name.plw binary results file.

Simulation_name.plg binary results file.

Simulation_name.plp XML file. Results limits for pumps.

Simulation_name.pty Text file. Dimensions for dimensioned pipes.

Simulation_name.sss -

Simulation_name.rou Text file. Node name for pressure-controlling path

through the network.

Simulation_name.chk Control file, error messages.

Simulation_name.log Control file, error messages.

Results analysis

NetSim Analyse is a tool for analysis and presentation of calculation results

produced by NetSim's calculation module.

This program is a module operating independently which only requires access to

simulation results produced using NetSim.

Analyse is started either directly from the menu under Modules or directly from

the explorer by enabling a results file from NetSim. Analyse can also be started

from the tools field.

To be able to open a calculation result, the files beräkningsnamn.PLW,

beräkningsnamn.PLG and beräkningsnamn.OUT have to be accessible in the

same library.

The program is structured using menus and tabs for presentation of results as

maps, graphs and text-based tables.

The tab Overview shows summaries of results for calculation. Click on the links

on the left to link to the various sections in the summary.

The tab Node table shows node results from the calculation and some input data

for calculation.

The tab Pipe table shows pipe results from the calculation and some input data

for calculation.

The tab Charts shows graphs for selected results from the results file. The graph

is configured via Settings.

The tab Map uses the network's geometry to display result plots and can show

supplementary background maps in DWG format.

The tab Animation shows the results of a dynamic calculation in graphic format.

The menu includes three panels, an archive, chart tools and map tools.

In File, you can Open an existing calculation and Save the contents in the Map

tab to various vector and raster formats, e.g. DXF, DWG, JPEG. You can use

Print to print out the contents in the Map tab. A dialog box opens in which you

configure the plot. Pumps opens a dialog box where you can edit design

conditions for every pump in the calculation, e.g. max. permitted lifting height.

(See the pump and pump type forms.) Reset docking state restores the dockable

windows in NetSim to the predefined position. About NetSim Analyse shows

version information. Exit closes NetSim Analyse.

Dockable windows

As in NetSim, you can take hold of a tab and drag it out to a separate window or

dock the tab to another window. Try it to see how it works! Remember, you can

restore the appearance using Reset docking state!

Doc-To-Help Standard Template Results analysis 59

Map

A map of the pipe network is created in the Map tab from the geometry

description in the results file. A map background in DWG/DXF format can be

loaded as a supplement to this screen. Selected calculation results and input data

are displayed as “tooltips” when the cursor is moved next to the object. Nodes

are displayed as solid circles (green). Production plants are displayed in red.

Nodes with consumption are displayed in magenta. Pipes are displayed with or

without colours depending on whether or not the results plotting has been

highlighted.

The Map tools panel is opened when you select the Map tab.

Layer settings

Here, you can select whether pipes, nodes, flows and comments are to be

displayed or hidden.

Zoom

This commands can also be found in the right-click menu. Zoom pipe and zoom

node highlight and centre the map over the pipe and node highlighted in Pipe

table and node table respectively.

Pipe settings

Select whether the map is to display results for supply pipes or return pipes.

Enter a value for scaling the pipe dimension (Scale factor for pipe dimension). A

scale factor of 1 displays the pipe without scaling. 100 shows the pipe scaled

with a 100 x dimension. Scaling allows you to see clearly which pipes have large

and small dimensions. Apply your choice by pressing Apply.

Plot limit

Select the value to be plotted in the map. You can choose from flow (kg/s),

velocity (m/s), temperature (°C), pressure (kPa), pressure difference (kPa),

pressure level (kPa) and pressure gradient (Pa/m). Select the Don't show option

if you do not want to display any results, just the pipe network. Select the

number of colours (interval) to be used to display the results. Enter an upper

limit and lower limit for the interval. The maximum and minimum values that

appear in the results file are displayed in brackets adjacent to the fields. For

example, if you specify 3 intervals and set the upper limit to 100 and the lower

limit to 50, all values up to 50 will be displayed in one colour, all values from 50

to 100 will be displayed in the next colour, and all values above 100 will be

displayed with the third colour. Apply your settings by pressing Apply.

Tooltip

When you move the cursor over a pipe or node in the map, calculation data can

be displayed in a dialog box adjacent to the node/pipe. For pipes and nodes,

select which data you want to view in the dialog box. For nodes, you can display

name, level (m), pressure in supply and return pipe (kPa), temperature in supply

and return pipe (°C), temperature difference (°C), flow from supply pipe to

return pipe in the node (kg/s), bypass flow in the node (kg/s) and power (kW).

For pipes, you can display name, diameter, pressure gradient in supply and

return pipe (Pa/m), velocity in supply and return pipe (m/s), flow in supply and

return pipe (kg/s) and heat loss value in supply and return pipe (W/m°C).

Text

Select Add legend and point to the place in the map where you want to position

your legend. If you want to move the legend, tag the command again and point

to the new location. Select Add title if you want to display the headers from the

model. You enter the headers in the calculation form in NetSim. (See also

Legend window).

Route

This function is used to point out a route through the network along which you

can display pressure, temperature and pressure gradient in a diagram. You have

to enter the node at which the route is to start and where it should end. The

routine itself finds the route through the network between the nodes which you

indicated. The routine selects in a branch to follow the pipe with the biggest

diameter. You can control the route which the routine selects by pointing to

nodes which the route has to pass through before you point to the end node. The

route selected by the routine is indicated in the map as you point. Remember,

you can allow a route to pass to an end point and return from there by continuing

to point to nodes. When you have started pointing to nodes with Add node(s) to

route, the routine continues to select nodes as long as you continue to point to

them. Finish pointing to nodes by pressing Esc. You can delete all nodes in the

route by pressing clear route. If you have defined a route, you can add to this

route by selecting Add node(s) to route or delete nodes by selecting Undo select.

The Route function can also be found in the map's right-click menu.

Select object

The select object function, which can be found in the map's right-click menu,

allows you to point to a pipe or node, and if you switch to the tab Pipe table or

Node Table, the data for the selected object is highlighted in the table.

Clear selections


The clear selections function in the map's right-click menu deletes the highlights

in the map which you saw when you opted to display highlighted pipes or nodes

in the map in the Pipe table or Node Table tab.

Create animation

This function creates a slideshow from a time series calculation. See the section

on time series calculations.

Background maps..

You can use this function to add background maps to your calculation. This

function opens a dialog box where you select the map to be displayed. The

format can be DWG, DXF or DGN. The dialog box remains open so that you

can select more maps or delete maps which you have added as backgrounds.

Legend window:

In the right-click menu, you can enable a floating window which shows the

interval limits in the map.

.

Charts

The tab Charts shows, in diagram form, a selected calculation value along the

route through the network which you created in the map. You configure the

diagram using the tools in the chart tools panel and in the right-click menu.

Plot settings

Select which calculation value is to be displayed in the diagram. You can choose

from pressure and pressure level in the units kPa, mvp and bar, Pressure

gradient in the units Pa/m and bar/km and temperature °C. If cavitation pressure

is selected, the limit for cavitation in the supply pipe and return pipe is

displayed. Select Show level if you want to [go via the nodes elevation.

Construction curve 1

Enter a name and value and select whether the temperature in a supply pipe or a

return pipe is to form the basis of density calculation, and there is a pressure

value which you enter. This curve can, for example, show where there is 16 bar

of pressure along the route in a plot of pressure level. Select/deselect Show to

enable/disable this curve.

Construction curve 2

The same function as Construction curve 1.

Zoom function

You can enlarge a section of the diagram. Hold down the cursor and drag it to

the side. Restore the diagram by selecting Undo zoom in the right-click menu.

Select data point

Click on a point in the diagram to display the coordinates for the point in the

diagram in the upper right-hand corner. The node name and curve values are

displayed in the bottom left-hand corner. You can use the left/right arrow keys to

move along a curve, and use the up/down arrow keys to toggle between curves.

Right-click menu

You can use the right-click menu to save the diagram to a file/cutout in a range

of formats/printers. Check the scaling of the diagram axes, enable/disable grids

in the diagram and adapt colours and styles for the curves.

The bottom right-hand corner of the diagram shows the time step from which

the results are displayed. The total number of time steps included in the

calculation. If the calculation includes more than one time step, you can select

time steps using < >.

Node table

Node table displays all calculation results for the nodes in a grid.

You can filter and sort in the grid and copy data from there to Excel. You can

move the columns so that the sorting suits your needs. Take hold of a column

and drag it to the right or left to move it. The table tabs are sorted by double-

clicking the table column headers. You can enable/disable columns by right-

clicking in the header row.

In the right-click menu, you can opt to view a node in the map, select Show on

map. Make sure that you have clicked on Map to load it beforehand. You can

select several nodes in the table by holding down Ctrl or Shift. You can select

single or multiple rows by pressing Shift/Ctrl and use the clipboard to copy to

text or an Excel file by pressing Ctrl+C / Ctrl+V.

You can search on node names with the right-click menu.

The filter function can be used to filter values less than, greater than, between

limits and beyond limits.

The bottom right-hand corner shows the time step from which the results are

displayed. The total number of time steps included in the calculation. If the


calculation includes more than one time step, you can select time steps using <

>.

Pipe table

Pipe table displays all calculation results for the pipes in a grid.

You can filter and sort in the grid and copy data from there to Excel.

The bottom right-hand corner shows the time step from which the results are

displayed. The total number of time steps included in the calculation. If the

calculation includes more than one time step, you can select time steps using <

>.

The table tabs are sorted by double-clicking the table column headers.

The filter function can be used to filter the selected column in the table.

In the right-click menu, you can opt to view a pipe in the map, select Show on

map. Make sure that you have clicked on Map to load it beforehand. You can

select several pipes in the table by holding down Ctrl or Shift.

The right-click menu also includes a search command which searches on pipe

name. You can select single or multiple rows by pressing Shift/Ctrl and use the

clipboard to copy to text or an Excel file by pressing Ctrl+C / Ctrl+V.

You can move the columns so that the sorting suits your needs. Take hold of a

column and drag it to the right or left to move it.

Out

The tab Out shows input data for the calculation and calculation results for

nodes, pipes, pumps, production plants, etc. The pipes dimensioned by NetSim

can also be found here, as can a cost calculation if this has been specified in the

calculation. The min/max. values for nodes and pipes appear at the bottom of the

screen.

The dimensioned pipes are only suggestions and must be entered in NetSim to be

applicable.

Animation

The tab Animation shows the results of a dynamic calculation in graphic format,

a time series calculation. You can simulate a cold plug or show what it looks like

when you load the network. If you have to execute a time series calculation, you

must configure the input data file prior to calculation. How to configure this is

described under Modelling/system data forms earlier on in this manual.

Model management

General The definition of the hydraulic network to be calculated is summarised under a

model name in NetSim. This means that the pipes and nodes, production plants,

pumps, etc. to be included in the network all have data in the model which has to

be calculated. In NetSim, the description of nodes, pipes, etc. is divided between

two types of data table , object data tables and model data tables. Names,

coordinates, lengths are registered in the object tables. Connections between

objects (pipe–node, pipe–pump, etc.), operating data, e.g. power, cooling, lifting

height, pipe dimension are registered in model data tables.

Model concepts A model in NetSim is made up of:

A network geometry - a number of pipes connected to one another in

nodes

Boundary conditions - Values for pressure, flows, powers and

temperatures which are given to nodes and pipes. These values can be

given directly to the pipes and nodes, but also be applied to these

indirectly via other objects such as pumps, production plants, etc.

Calculation parameters such as general load factor, ambient

temperature, etc.

In NetSim, all objects such as pipes, nodes, pumps, etc. are collected in the same

database and the model constitutes, in the actual sense, the “linking” of the

above data which has taken place under a model name in the database. This

means that one and the same object may be included in several models in the

database. Regarding the objects as actual physical objects which can be assigned

different properties in different models makes this easier to understand.

Doc-To-Help Standard Template Model management 65

Objects in the database are identified by an internal ID and a unique name. This

means, for example, that two pipes in two models with the same name are one

and the same object but with two sets of attributes. A set of attributes in either

model.

Models can be of two different types, normal mode or planned mode.

In the database, it is assumed that a model of a pipe network describes normal

mode. This model is assigned normal mode type in the model form. All other

models which include nodes and pipes from this model are planning models and

are assigned planning model type.

When a model describing normal mode is present, it is recommended that you

create a planning model which is a copy of the normal mode model and that you

assign the model type planning to this copy. You can delete and add pipes and

nodes in this planning model without affecting the normal mode model.

When an object, node or pipe is present in two models and the object is deleted

in one of the models, the object disappears in this model only. The object

remains in place in the other model. The object is also deleted from the database

only when the object appears in only one model.

A planning model can be expected to become obsolete as the normal mode

model is changed. This is why the content of a planning model should be

checked against the foundation on which it is based if it is used after a period of

dormancy. This check can take place graphically by visually comparing a

drawing from the relevant model or by applying an appropriately formulated

SQL script which compares the content of the two models and points out the

differences between the models.

Model-specific data To be able to operate NetSim correctly, it is crucial to understand how the

program differentiates between data which is object-specific and data which is

model-specific. The figure shows which data belongs to which group for the

objects in NetSim. Not all data is displayed in the figure. Data which is rarely

used and data which has no effect on the calculation is not shown.

Objects

In NetSim, “objects” refers to pipes, nodes, production plants, accumulators,

heat exchangers, pumps and valves. The object has an internal ID which is

hidden from the user and a name which is unique within the object type. I.e.

there is e.g. only one pipe with the name P1189, but there could well be a node

with the same name! A range of information is linked to each object

individually, and a range of information is linked to every object's occurrence in

a model.

Model

A model in NetSim connects pipes and nodes to a network, and the other object

types are connected to this network.

Example:

You create a copy of a model, and in this copy you switch the pipe type

in a pipe. In the original model, the pipe still has the same pipe type as

before.

You want to place a pressure increase station in a pipe in the copy. You

can then choose to place in the pipe a pressure increase station which

you previously created in another model. Either pressure increase

station then has its own data in the two models.

You delete a pipe in the copy. The pipe remains in place in the original

model.

You create a new pipe in the copy. The new pipe appears only in the

copy, no other model.

A range of data which controls the calculation process and results also belongs to

the model.

Directory data

Pipe types, pump types and customer types are all examples of directory data.

Doc-To-Help Standard Template Model management 67

±

Summary: object data - model data

Object-specific data Production plant

ID

Name

Comments

Accumulator

ID

Name

Comments

Heat exchanger

ID

Name

Comments

Pump

ID

Name

Comments

Valve

ID

Name

Comments

Pipe

ID

Name

Comments

Length, supply/return pipe [m

Coordinates for direction changes

Ambient temperature [°C

Node

ID

Name

Comments

Type

x coordinate

y coordinate

z coordinate

Model-specific data Temperature [°C

Power [kW

Flow [kg/s

Static pressure/Location [kPa

Pump type

Max./min. power

Temperature programmes

Volume [m³

Max./min.temperature [°C

Initial temperature [°C

Nominal power [kW

Heat loss [kW/°C

Ambient temperature [°C

Basic power [kW

Temperature dependency [kW/°C

Location, supply/return pipe

Location, node 1/2

Fixt lift, supply/return pipe [kPa

Revs, supply/return pipe [revs/s

Location, node 1/2

Pump type

Reference value, node

Reference value, type

Reference value [kPa

Fixt pressure reduction, supply/return pipe [kPa

Location, node 1/2

Opening degree [0-90°

Valve type

Reference value, node

Reference value, type

Reference value [kPa

Pipe type, supply/return pipe

Closing mode

Network level

Resistance factor, supply/return pipe

Dimensioning criteria

Output [kW / Flow [kg/s

Cooling/return temperature [°C

Shunt temperature [°C

Bypass [mm or Kv value

Create a new model Connect to the database (Menu → File → Connect database )

In the File menu, select Model Create new.

Give your model a name in the model name field. The name must include no

more than 255 characters, but we recommend that you keep your

descriptions a little shorter than that!

The new model has been created with a range of predefined values for

factors and dimensioning. Review and change these to the values you

require in your model and save the model by pressing the Create button. If

you use the Cancel button, no model will be created.

Select your new model as the current model in the Model toolbox.

You can now create pipes in the new model or import a NetSim calculation file

to the model.

Copy a model This function is used to create, under a new name, a complete copy of the model

you choose to copy. In this copy, you can add/remove pipes and nodes, change

pipe dimension, change load cases, production, pumpings, etc. without affecting

the master for the copy. What you should not do if you want the master to

remain untouched is change the geometry (lengths and coordinates) of pipes and

nodes which are the same in the two models!

Connect to the database (Menu → File → Connect database )

In the File menu, select Model Copy.

Give your model a name in the field. The name must include no more than

255 characters, but we recommend that you keep your descriptions a little

shorter than that!

The current model is copied and created when you press OK!

If you use the Cancel button, no copy will be created.

Select your new model as the current model in the Model toolbox.

Delete a model You can use this function to delete a model from the database.

If you delete your current model, you should connect to the database again and

select a model in order to update information in graphics and forms.

Connect to the database (Menu → File → Connect database )

In the File menu, select Model Delete.

Your current model is preselected. Confirm by pressing the Yes button, or

cancel by pressing the No button.

Doc-To-Help Standard Template Pressure regulations – pumps and valves 69

Pressure regulations – pumps and valves

In our experience, pressure regulations in the form of pumps and valves are the

area which users generally find hardest to review! The effect of all pressure

controls over the entire network needs to be taken into account, and the user has

to provide sufficient boundary conditions for the degrees of freedom introduced

to every pressure regulation.

Location of pumps and valves

Pump/Valve is a pressure change in

the pipe “between” the pipe and node

1 or node 2 in the supply pipe, the

return pipe or both. Thus a pipe

contains four positions where

pressure changes can take place.

The pressure change can be fixed or

controlled by a reference value. The

pressure change can be unknown in

just one of these positions. All the

other pressure changes in a pipe must be specified in some way. There is one

exception. If the a pumping is defined in both supply and return in the same pipe

at the same end of the pipe and the head is undefined in both supply and return

will the total head required to obtain the pressure/differential pressure given for

the set point node be divided between the supply and return pumping according

to the quota given for the pumping. Although in many cases it is valid, it is in

most cases preferable to locate the pump or valve next to node 1 in the pipe.

Further, if a pump lift is defined in both the supply and return of a pipe, pumping

may not be placed in adjacent pipes.

Pressure changes can also be described by defining PUMPS and VALVES

which are connected to these positions [at the pipe.

When “undefined” pressure changes are introduced in the pipes, corresponding

reference values for pressure must be introduced in the model. This is done by

specifying nodes and pressures in these nodes. The stated pressures in these

nodes relate to the supply pipe pressure, the return pipe pressure or the difference

between the supply and the return pressure, the differential pressure.

Both pump and valve can be supplemented with a characteristic. In the case of

the pump, for a given speed, the link between flow, pressure and power

requirement. In the case of the valve, the link between opening degree and

capacity (Kv value) is stated. These characteristics are presented to the

calculation module in the calculation file using the keywords *PUMP and

*VALV. These keywords are sent to the calculation file only if the

characteristics have been defined.

A pump or valve can be viewed as a “framework” so as to control pressure

changes in the four named positions in the keyword *PIPE, and to control

supply, return or differential pressure in the keyword *NODE and ensure that the

boundary conditions are sufficient in the model.

The pump location is indicated in the keyword *PUMP: supply+return, supply,

return or in node. (The last option is used only for pumps in production plants.)

Current speed for location in supply pipe, current speed for location in return

pipe followed by the characteristic. Note that the end of the pipe at which the

pump is located is indicated in *PIPE.

The location of the valve is indicated in *VALV: supply+return, supply or

return. Current opening degree 0 – 90° from closed position, followed by the

characteristic. Note that the same opening degree is applicable to both the supply

pipe and the return pipe and that the opening degree is always specified. This

means that a characteristic is never indicated for a regulating valve.

A pump and valve are given the name of the pipe in the calculation file. This

means that only one characteristic can be given to the respective “pipe” of either

pump and valve.

Therefore, there are a number of valid and invalid combinations that can be

entered by the user.

Example

The table below shows a number of combinations of locations of pumps and

valves in one and the same pipe with and without reference values. * in a field

means that the value is calculated.

(*) Location 0 : located in both supply pipe and return pipe, 1: located in

supply pipe, 2: located in return pipe

Reference values in nodes: If a number of reference values have been given in a

case, these may relate to the same or different nodes. It is important to note that

pressure regulations take precedence over a given reference value.

Node 1 Node 2 Node 1 Node 2 Supply Return

Case ΔP kPa ΔP kPa ΔP kPa ΔP kPa

Quota

(S/R) P kPa P kPa ΔP kPa

Location

0 1 2 Supply Return

Location

0 1 2

Opening

deg.

A 0 0 0 0

B 200 0 0 0

C * 0 0 0 300

D * 0 200 0 300

E * 0 * 0 0 20 15

F * 0 * 0 300 0 * 20

F2 * 0 0 * 300 0 * 20

F3 * 0 0 * 300 2 20

F4 * 100 0 0 300

G * 0 -200 0 300 1 *

H * 0 * 0 1000 500 1 *

I * 0 * 0 1000 500

J 0 0 * 0 2 5

K * 0 * 0 0 5

L * 0 0 * 300 1 * 2 5

M * 0 * 0 50 300 0 * *

revol. (rps)

PIPE NODE PUMP VALVE

Supply Return Setpoint

A: Pipe without pump or valve (pressure increase/pressure reduction).

B: Pump in supply pipe at node 1, lifts 200 kPa.

Doc-To-Help Standard Template Pressure regulations – pumps and valves 71

C: Pump in supply pipe at node 1, lift is calculated so that DP in

reference value node is 300 kPa.

D: Pump in supply pipe at node 1, lift is calculated so that DP in

reference value node is 300 kPa. Pump in return pipe at node 1, lifts

200 kPa

E: Identical pumps in the supply pipe and the return pipe at node 1 with

different speeds. Lift in respective pipe function of speed

F: Identical pumps in the supply pipe and the return pipe at node 1 with

different speeds. Lift in return pipeline function of given speed. Lift in

supply pipe is calculated so that DP in reference value node is 300

kPa. The speed is calculated.

F2: Invalid! Identical pumps in the supply pipe and the return pipe, but

located at either end of the pipe!

F3: Pump at either of the pipe in supply and return. Supply pump lifts so

that DP in reference value node is 300 kPa. Speed is NOT calculated!

Return pump operates at set speed.

F4: Pumping at both ends of supply pipe. One pumping set to 200 kPa, the

other calculated so that DP in reference value node is 300 kPa. NO

PUMP CURVES can be utilised!

M: Pumpning in the same end of pipe in both supply and return side of

pipe. The total lift in supply + return is calculated so that DP in

reference value node is 300 kPa. Pump speed is calculated. The total

lift is divided between supply and return side according to the Quota

given for the pumping.

G: : Pump in supply pipe at node 1, lift is calculated so that DP in

reference value node is 300 kPa. Valve in return pipe throttles 200

kPa

H: Cannot be resolved! Pump in supply pipe at node 1, lift is calculated

so that supply pressure in reference value node is 1000 kPa. Valve in

return pipe throttles so that return pressure in reference value node is

500 kPa. Pump speed is calculated!

I: Can be resolved! Pump in supply pipe at node 1, lift is calculated so

that supply pressure in reference value node is 1000 kPa. Valve in

return pipe throttles so that return pressure in reference value node is

500 kPa. Pump speed is not calculated!

J: Return throttling at node 1. Valve open 5°, pressure change

calculated.

K: Supply and return throttling at node 1. Valve open 5°, pressure

changes calculated.

L: Can be resolved if pump and valve are located at either end of the

pipe! Pump in supply pipe at node 1, lift is calculated so that DP in

reference value node is 300 kPa. Valve in return pipe open 5°

Import from CAD

Data import from CAD file (additional function)

This module in NetSim allows you to convert the contents of a DWG file to a

calculation model in NetSim. The DWG file must be designed according to a

few simple rules so that it can be interpreted. This module includes tools which

you can use to edit/create the file to be interpreted. This module is an additional

function to NetSim and can be ordered from Vitec.

Drawing style

Pipe:

A 2D polyline or 3D polyline. All pipes which connect to a T-piece must be

broken up in the T-piece. (Only 2D information from a 3D polyline is utilised.)

Elevation:

A text string (Single line text). Values are stated in metres. Decimal points must

be used as decimal separators. Any leading text, e.g. z or equivalent, is ignored.

Doc-To-Help Standard Template Import from CAD 73

If elevation is not given at the pipe end, this is set to 0. The interpreter reports

which nodes have no elevation.

Pipe type:

A text string (Single line text). Max. 80 characters. The string must not contain

blanks. Check that NetSim includes the pipe types occurring in the drawing

before you interpret it. The interpreter selects an existing pipe type from the

NetSim type directory if the type is not present, and replacements are displayed

in a report.

Node name:

A text string (Single line text). The node name must not contain more than 8

characters. If you enter a node name which already exists in NetSim, the name

will be replaced with errorN, where N is a serial number. A check is carried out

in NetSim to ensure that N is greater than any N values which may occur in

nodes in NetSim called errorN. As a consequence, the interpretation does not

create a node with the same name as an existing node in NetSim. No symbol is

needed for the node per se, this is created during interpretation; but your work

will be easier if you place a circle at the point where the node should be!

Pipe name or Prefix to pipe name:

A text string (Single line text). Max. 8 characters. Note that if a prefix is used,

the total number of characters for prefix + lettering must not exceed 8. If a prefix

is used, the pipes will be lettered consecutively within the prefix. The name is

checked in the database in order to prevent duplicates. If you set a pipe name in

the drawing which already exists in NetSim, this name is replaced by errorN,

where N is a serial number. If you use a prefix, the letter is listed by the pipe

names that exist with this letter in the database. As a consequence, the

interpretation does not create a pipe with the same name as an existing pipe in

NetSim.

Place the node name and elevation adjacent to the ends of the pipes.

Place the pipe name and pipe type “in the middle of” the pipes. Remember that

the insertion point of the text is the point to which the distance is measured.

Interpretation

Start the interpretation module from the NetSim menu File-Importera DWG

[Import DWG.

Open the file to be converted.

All layers in the file are displayed in the module. You have to select which

layers do not contain information and classify what type of information is

present in the layers which contain data for your model.

Specify drawing layers

As you can see, a layer can include several types of data if there are different

entity types (TEXT/POLYLINES), and the same data type can appear in several

layers. However, it is both safer and more convenient for you if you limit the

number of layers in the drawing to just the ones you need. I.e. get rid of

background maps, tappings/vents, etc. and make your work easier!

I

n

t

h

e

I

g

n

orera [Ignore column, you have to select the layers in the drawing which do

NOT contain data to be processed.

Select which layer/layers includes/include the pipe geometry (polylines).

Select which layer/layers includes/include node name (TEXT), pipe name

(TEXT), pipe type (TEXT), Z level (text).


Naming methods and prefixes

Prefix ledningsnamn [Prefix pipe name:

Pipe names are created as a given prefix + a serial number.

Prefix knutnamn [Prefix node name:

Node names are created as a given prefix + a serial number.

Distans [Distance:

The distance within which text is searched for pipes and nodes.

Hämta prefix ur karta [Get prefix from map:

If this option is selected, all pipe names given in the map which match the values

you entered in the field will be given this prefix + a serial number.

Every value in the list must be separated with a semicolon. Do not use blanks in

the list. Identification is shift-sensitive.

INTERPRETATION

Interpretation starts when you enable the Tolka [Interpret button.

The drawing is analysed and a log opens when the process is complete.

Interpretation has created a model which has the same name as the drawing

which you interpreted.

Analyse the log. If it contains a “lot” of comments. Correct the drawing, save

the drawing and close the drawing interpreter. Delete the model created and

reopen the drawing in the interpreter. (If you do not delete the model, the pipes

and nodes in the model will block the node and pipe names that you have in the

drawing.)

Create a calculatable model

Open the model which your interpretation created. It has the same name as the

drawing file.

Create a production plant, link it to a node in the model. Enter in the production

plant the supply pipe temperature, static pressure and how the pressurisation is

positioned, in the supply, the return or between the supply pipe and the return

pipe, and also how close to the supply pipe as a percentage.

Enter an power and cooling or return temperature in a node.

Open the calculation form and enter there the differential pressure in a node,

global factors, dimensioning criteria and pressure calibration factors.

Specify and name a calculation file and execute a calculation.

It may be a good idea to check that the network is connected together before you

execute your calculation. Use Identifiera hål i modell [Identify holes in model

from the Verktyg [Tools menu in NetSim.

Combine interpreted model with existing model

There are not so many stages here!

Open the calculation form, specify and name a calculation file, select Visa

manuella inställningar [Display manual settings and press the Beräkna [Calculate

button.

Do not start the calculation module without opening the calculation file in

Anteckningar [Notes (the button at the top right).

Search for the first row starting with *NODE, delete all rows above this row and

save the file. If you do this, you will retain all model headers and factors

unchanged.

Close the calculation module, in NetSim open the model which you have to

supplement with pipes from your interpreted drawing. In the menu, select Arkiv

[File - Importera beräkningsfil [Import calculation file and highlight your file.

The pipes and nodes in the file now become members of the model!

Important!

The pipes which you import must be linked in one or more cases to an existing

node in the model to which you import. If you take the file as it is, you have to

search for the “connection points” and select there the “new” pipe and switch the

node from the node which came with the import to the node which already

existed in the model at the “connection point”. There will now be a node left

over in the model which has no pipes to it. You have to delete this node. Search

for it in the node table and select Ta bort object [Delete object.

Of course, you can switch the node names directly in the import file, but if you

do then remember that the name has to be changed both in the keyword *NODE

and at the point where it occurs in the keyword *PIPE. The safest thing to do it

use search/replace when you do this!

Editing a drawing in the interpretation module

The drawing function in the interpretation module is a CAD component. This

means that you can edit, add and create pipes in the module using “standard


CAD commands” found in the menus Edit, Draw and Modify and save your

changes via the File menu.

Data import from network information system

With NetSim's data storage in a powerful relational database, receiving data

exports from various network information systems and building calculation

models in NetSim is generally an uncomplicated procedure. Vitec Energy has

prepared procedures for importing from most major systems on the market.

Contact Vitec for more information.

Doc-To-Help Standard Template Consumption data 79

Consumption data

Import file for customer data

Customer data can be imported to the NetSim database via an ASCII file in a fixt

format.

All data belonging to a customer (a record in the import file) is given in one and

the same row, and all fields have to be separated by the character ¤ (ASCII

character no. 164).

Every record (row) must contain 29 fields. If the last field Memo and the field

separator ¤ are omitted between the 24th and the 25th field, the value 0 is

recorded in the Memo field. The fields must be entered in the sequence shown in

Figure 1 below. There must be a value in fields marked NOT NULL. Other

fields can be left blank.

In fields with data type VARCHAR2, alphanumeric text strings can be entered

with a maximum number of characters as stated in ( ). In fields with data type

NUMBER, only numerical characters can be entered with a maximum number of

characters as stated in ( ). NUMBER(15,3) means that 15 digits can be entered in

the field, of which 3 are decimals. NUMBER(2) means that figures between 0

and 99 will be accepted. See also section Input data in general below.

Example, Figure 1: 2250¤12250¤ACME AB¤Kv Bofinken 4¤Trastvägen 3,

Solna¤2250¤LA102¤LA102¤1¤22¤7¤37¤1700¤2007-09-

02¤256¤1.222¤191¤0¤3368¤0¤50¤46¤0¤0¤New customer¤¤¤¤¤

Import file preparation

If the user himself is going to manufacture the import file from a export from a

debit system, the easiest way to do this is using a spreadsheet program such as

Excel or similar, unless the debit program supplies the data directly in the

intended format.

1. Import the data to the spreadsheet program.

2. Arrange the data in columns in the same sequence as shown in Figure 1

above.

See Customer data field description below.

3. Calculate the field values not obtained from the debit program in

the spreadsheet program, or enter an appropriate default value. Check

att the max. number of characters in each field is not exceeded.

4. Open the control panel and national settings. As a

list separator, enter the character ¤ under the tal [figures tab

5. Save the spreadsheet in semicolon-delimited format with a TXT

extension.

6. Close the spreadsheet.

7. Reset the list separator in national settings to its regular value.

Import customer data to NetSim databas

1. Start NetSim, connect to the database and select the model.

2. Select Arkiv [File → Kunddata [Customer data.

3. Select what you want to do.

The following options are available: Import endast nya [Import new

only, Importera alla [Import all, Kopiera kunder [Copy customers,

Export kunddata [Export customer data or Ta bort all [Delete all.

Select Lägg endast nya [Add new only if only new customers are to be

set up and existing customers in the database are not to be updated.

Select Importera alla [Import all if the data in the import file is to

replace the data in NetSim.

Select Kopiera kunder [Copy customers if customers are to be copied

from another model to the current model. The import file is not used in

this option.

4. Select the file.

5. A message is displayed when the import is complete, and a log is

displayed which indicates where any errors were found in the import

file.

Update nodes with consumption from customer data

When updating nodes with consumption from customer data, all customers' loads

are summed to the node to which the customer is related. The resulting cooling

or return temperature written to the node is a weighted average value for all

customers connected to the node. The update affects the active model only.

1. Start NetSim, connect to the database and select the model.

2. Select in the menu Arkiv [File → Beräkning [Calculation.

3. In the kundfaktorer [customer factors section, enter a value for outdoor

temperature.

4. Indicate the customer data field from which som the customer's power

is to be calculated.

5. Indicate the network level to which summing is to take place.

6. Select whether cooling or return temperature is to be transferred to the

nodes.

8. Press the Uppdatera knutar [Update nodes button, or press the Bypass

button if

bypasses at customers' premises are to be summed to the nodes.

9. Close the form.

Customer data field description

MODEL: Not specified in import file. On import, the customer is bound

via the node references given to the customer and active model


to model. If no nodes are given on import, the customer is not

bound to any specific model.

1. FACILITY ID: The unique code which identifies the customer and

the location. NULL: No. VARCHAR2(40).

2. CUSTOMER ID: The code which identifies the customer, may differ from the

plant ID.

3. CUSTOMER: Customer name.

4. PROP. DESIGNATION: A property designation, where applicable.

5. ADDRESS: Address.

6. NODE LEVEL 1: The node to which the customer belongs in the model in

level 1. The node must belong to the model.

7. NODE LEVEL 2: The node to which the customer belongs in the model in

level 2. The node must belong to the model.

8. NODE LEVEL 3: The node to which the customer belongs in the model in level

3. The node must belong to the model.

9.STATUS: The customer is existing or planned.

Enter a value 1 for an existing customer and 2 for a planned

customer in the import file.

10. CUSTOMER TYPE POWER: Enter a number for a type curve. Type curve 1- constant

factor 1.0 is preinstalled. Controls which type curve is to be

used for the customer for power requirements. If the specified

curve is note present, a new curve is created with factor = 1.

11. CUSTOMER TYPE COOLING: Enter a number for a type curve. Type curve 1 - constant factor

1.0 is preinstalled. Controls which type curve is to be used for

the customer for cooling. If the specified curve is note present,

a new curve is created with factor = 1.

12. CUSTOMER TYPE RETURN TEMP.:Enter a number for a type curve. Type curve 1 -

constant factor 1.0 is preinstalled. Controls which type curve is

to be used for the customer for return temperature. If the

specified curve is note present, a new curve is created with

factor = 1.

13. CATEGORY FACTOR: When energy consumption is summed to nodes, energy

consumption is divided by the category factor.

14.PERIOD: The export from customer data may include information on the

period from which the details are taken. NULL: No.

VARCHAR2(30).

15. NOMINAL POWER: The customer's nominal power, kW

16. NOMINAL FLOW: The customer's nominal flow, kg/s

17. HEAT CONSUMPTION I: Consumed energy for period 1, MWh

18. HEAT CONSUMPTION II: Consumed energy for period 2, MWh

19. WATER CONSUMPTION I: Consumed water for period 1, m3

20. WATER CONSUMPTION II: Consumed water for period 2, m3

21.AVERAGE COOLING: The customer's average cooling, degrees C. Customer data

includes details on either average cooling, or average return

temperature. When importing customer data, 0 is entered as the

input data value for the one of the parameters which is not

given.

22. AVERAGE RETURN TEMP.: The customer's average return temperature, degrees C.

23. AREA/VOLUME: Area or volume (m2 or m3). When summing customer load to

nodes, the value is converted to kW (1:1).

24.BYPASS DIAMETER: Bypass in FC, mm. When summing

customer load to nodes, all bypasses are summed in FC and an

equivalent bypass is calculated for the node.

25. COMMENTS: Plain text field

REG. DATE (TODAY): Not specified in import file. This field shows when registration

took place in NetSim. The field is completed automatically with

system's time specification regarding when the import took

place.

26POSTAL ADDRESS: Postal address for when the notification function is used.

27. NOTIFICATION 1: The customer's name for when the notification function is used.



Input data in general

In fields with data type VARCHAR2, alphanumeric text strings can be entered

with a maximum number of characters as stated in ( ). In fields with data type

NUMBER, only numerical characters can be entered with a maximum number of

characters as stated in ( ). NUMBER(15,3) means that 15 digits can be entered in

the field, of which 3 are decimals. NUMBER(2) means that figures between 0

and 99 will be accepted. See also section Input data in general below.

Summing of customer data to node

Index I indicates the i:th customer of n related to a node.

Summing of energy period 1:

Summing of energy period 2:


Summing of nominal power:

Summing of area/volume:

Summing of nominal flow:

Summing of water consumption period 1:

Summing of water consumption period 2:

Summing of cooling:

Summing of return temperature:

Summing of equivalent bypass:

Factor-controlled power

The function “Factor-controlled power” means that when power and cooling are

summed from customer data to the nodes in the model, a temperature is specified

as a parameter. The temperature specified is the outdoor temperature for the

current load case. Every subscriber is allocated a type which corresponds to a

type curve. This type curve specifies for different outdoor temperatures the

factor by which the customer's nominal power has to be corrected in order to

attain the normal power in this operating case. See the example in the diagram

below.

Factor-controlled cooling

Information on average cooling over the period to which the information applies

(normally one year) is stored for the customer in the customer data register. The

function “Factor-controlled cooling” means that when power and cooling are

summed from customer data to the nodes in the model, a temperature is specified

as a parameter. The temperature specified is the outdoor temperature for the

current load case. Every subscriber is allocated a type which corresponds to a

type curve. This type curve specifies for different outdoor temperatures the

factor by which the annual average cooling has to be corrected in order to attain

the normal cooling in this operating case. See the example in the diagram below.

The program which sums the load from customer data interpolates/extrapolates

from the curve the factor applicable to every type for the temperature specified

as a parameter on summing.

We assume that the customer type, viewed from this angle, will not be registered

previously in the customer database. Therefore, every customer must be assigned

customer type 1 on import. This customer typ 1 is a linear curve with the factor

value set to 1.0 and is predefined in the table.

Doc-To-Help Standard Template Calculation module's input data file 85

Factor-controlled return temperature

If we assume that the return temperature recorded is the annual average return

temperature, we can utilise the customer type above in the same way as the

factors for cooling. We assume that the customer type, viewed from this angle,

will not be registered previously in the customer database. Therefore, every

customer must be assigned customer type 1 on import. This customer typ 1 is a

linear curve with the factor value set to 1.0 and is predefined in the table.

Calculation module's input data file

Summary The calculation module's input data file can be used by an experienced user to

directly create input data for the calculation module and define more complex

boundary conditions than is possible in the database.

The input data file is based on a concept involving keywords combined with

plain text. It can be created manually using an editor or from a NetSim database.

The editor's only restriction is that the input data file must be saved as an ASCII

file. Of course, you can use an input data file created by NetSim as a master and

manipulate this in a editor.

Data format

The input data file contains keywords. Every keyword is linked with a specific

number of figures and text strings. Keywords, figures and text strings can be

input freely, with the exception of the following rules:

Keywords must start in column 1.

Only keywords are permitted in column 1.

The specified sequence of figures and text strings must be followed.

A figure is only recognised as a figure if there is a space on either side

of it.

A text string is only recognised as a text string if it is enclosed in

inverted commas (“ ”).

An unknown value can be indicated by an asterisk “*” or the figure

9.9999E+30.

Explanatory text may be entered in a keyword. All text which is not a figure or a

text string as defined above will be ignored. As a result, the keywords in the

example below are all identical: *PFAC 1.3 0.3

*PFAC Faktor 1: 1.3 Faktor 2: 0.3

*PFAC k = 1.3 + 0.3 * Diameter.

The order of the keywords is not free. A keyword which refers to another

keyword must be defined after the primary keyword. An example is the pipe

keyword which refers to the names of nodes. This is why the pipe keyword has

to be placed after the node keyword.

Summary: keywords

All input data for the calculation module can be entered with the following

keywords:

- Accumulator *ACCU

- Stop input data *STOP

- Dimensioning *DIAM

- Flow factor *FFAC

- Supply/return *FORW

- Implicitly defined pressure tank *PSUB

- Node *NODE

- Pipe *PIPE

- Local pipe dimensioning *LDIM

- Ambient temperature *ATMP

- Pump, booster or regular *PUMP

- Pump administration *PQTA

- Shunt valve *SHNT

- Simulation cooling *COOL

- Stop criterion *ILIM

- Simulation mode *VERS

- Temperature *TEMP

- Title *TITL

- Pressure loss correction *PFAC


- Water hammer calculation *DYNP

- Valve *VALV

- Heat exchanger located in a pipe *HEAT

- Steam in supply pipe *STEA

- Year simulation *YEAR

Keywords

Keyword *ACCU

The keyword *ACCU is used to define an accumulator in a node.

FORMAT:

*ACCU <NodeID, Tmax, Tmin, Volacc, Hloss, Tini, Ts, Pnom>

Where:

NodeID: Node identification

Tmax: The maximum temperature in the accumulator. (°C).

Tmin: The minimum temperature in the accumulator. (°C).

Volacc: The accumulator's active volume. (m3).

Hloss: A heat loss coefficient which, when multiplied by

the average temperature in the accumulator and the average

ambient

temperature, gives the loss in kW. (kW/°C).

Tini: Initial average temperature in the accumulator. (°C).

Ts: The average ambient temperature. (°C).

Pnom: Nominal power. If simulation is used for

dimensioning of accumulators, Pnom must not be entered, i.e.

9.9999E+30 or “*” must be entered. (kW). If Pnom is positive

energy is stored in the accumulator. If Pnom is positive energy

is delivered from the accumulator. Note that if *COOL is

active you have to think the other way around.

Note that the keyword *ACCU must be entered after the keyword *NODE.

Note that if the node is provided with an accumulator, no other devices are

permitted in the node (e.g. a bypass).

Keyword *ATMP

The keyword *ATMP is to be used to enter individual ambient temperature.

FORMAT:

*ATMP < ledningsid, omgivn.temp>

Where:

ledningsid: pipe identification

omgivn.temp: specific ambient temperature for the pipe. (C)

This keyword can be entered only after *PIPE, where all pipe identifications are

entered. If the keyword is entered earlier, an error message will be received as

the pipe is unknown at this point.

The keyword can be omitted entirely.

Example:

*ATMP ledning: “A3F” omgivn. temp.: 10 C

Note that if the option of varying the ground temperature in an annual run is

used, the program ignores the temperature variation in the pipes assigned an

individual temperature via the *ATMP keyword.

Keyword *COOL

This keyword is used to calculate a cooling system instead of a heating system as

normal.

This keyword has no arguments.

Keyword *DIAM

This keyword is used to define the pipe directory used for dimensioning of one

or more pipes. This keyword must come before the pipe keyword.

FORMAT:

*DIAM <krit1 krit2 LIM “typ”

“typ1” d1 v1 k1

“typ2” d2 v2 k2

. . . .

“typ20” d20 v20 k20 >

Where:

krit1: is the velocity criterion in m/s.

krit2: is the gradient in Pa/m.

LIM: is the pipe diameter in mm below which the velocity criterion

and above which the gradient are to be applied.

Typ: The default pipe type is used for a possible flow route

through a ring connection. The dimension is used only when

all pipes in a ring connection have unknown dimensions. In

this case, the type will be specified as “typ” regardless of the

dimensioning criterion. The possible flow route is indicated by

* in the input data element of the printout.

typ1: name of the pipe type (max. 8 characters enclosed in inverted

commas)

d1: the internal diameter for the pipe type (mm)

v1: heat transfer coefficient (W/(°C × m))

k1: roughness for the pipe type (mm)

This list may include up to 20 different pipe types. If fewer than 20 types are

specified, the table must be ended with a “/” (slash).

Note that if e.g. the velocity criterion (1 m/s) is to be used for all diameters,

krit1, krit2 and LIM must be 1.0, * and * respectively. Similarly, if the gradient

criterion of 103 Pa/m is to be used for all diameters, krit1, krit2 and LIM must be

*, 103.0 and * respectively.

Example:


*DIAM Velocity criterion 3.0 m/s

Gradient criterion 1.0 Pa/m

Limit 75.0 mm

Default pipe type “N200”

Type I.Diam v k

-----------------------------------

“N050” 48.7 0.330 0.05

“N100” 89.3 0.350 0.05

“N125” 114.7 0.320 0.05

“N150” 156.8 0.340 0.05

“N200” 189.6 0.550 0.05

“N250” 215.4 0.440 0.05

“N300” 313.4 0.550 0.05

/

Keyword *FFAC

This keyword is used to specify a flow factor. The flow factor is a constant

which is multiplied by all flows and power demands.

FORMAT:

*FFAC <faktor>

Where:

faktor: Constant to multiply by all flows and powers.

If *FFAC is not entered, the value 1.0 is used.

________________________________________________________________

Example:

*FFAC Flow factor : 1.25

________________________________________________________________

Keyword *FORW

When the keyword *FORW is specified, only one calculation of the supply pipe

is executed. If nothing is specified, the program always calculates both supply

and return.

FORMAT:

*FORW

The keyword can be omitted entirely.

Example: *FORW Only supply pipe is calculated.

Keyword *HEAT

This keyword is used to describe the amount of energy supplied to the system

via a heat exchanger in the pipe. By default, heat supply takes place in a node.

The energy supplied to the system is dependent on the absolute temperature in

the pipe.

The power is defined as:

Power = A + B * T

where A: Constant

B: Constant

T: Temperature upstream of the heat exchanger in degrees

Celsius.

FORMAT:

*HEAT <ledningsid> <ände> <sida> <faktor A> <faktor B>

<pris1> <pris2> <pris3> <pris4>

Where:

Ledningsid: Name of the pipe in inverted commas.

Ände: Upstream or downstream end for positioning of

heat exchangers. Enter 1 for upstream end and 2 for downstream

end.

Sida: The water heater can be positioned in either the supply pipe or the

return pipe.

Enter 1 for supply pipe and 2 for return pipe.

faktor A: Power delivered to the pipe in kW.

faktor B: Power delivered to the pipe in kW.

pris1: The energy price for the energy. SEK/kWh.

pris2: C tax for the energy. SEK/kWh.

pris3: N tax for the energy. SEK/kWh.

pris4: S tax for the energy. SEK/kWh.

Example: *HEAT Ledningsid: “K01-K02”

Ände: 1

Sida: 2

Faktor A: 0.0000

Faktor B: 0.0000

Energy pris: 0.0000

C-tax: 0.0000

N-tax: 0.0000

S.tax: 0.0000

Keyword *ILIM

This keyword is used to define the stop criterion and relaxation of iteration.

FORMAT:

*ILIM <rlim> <relax> /

Where:

rlim: Relative stop criterion for pressure and temperature

calculations.

Relax Value for relaxation of the iteration.

This figure must be in the range between 0 and 1

A value of 0.8 indicates that only 20% of the difference between two iterations is

utilised.

If *ILIM is not specified, the defaults for rlim and relax are 0.005

and 0 respectively.

Example: *ILIM Iteration criterion: 0.001

Relaxation : 0.0 /

Keyword *VERS

This keyword is used to affect in what mode the simulation is preformed.

FORMAT:

*VERS <value>

Where:

value: The value is 1 or 2. This value affects a method used during

the simulation. Standard value is 1. Change the value to 2 if

the simulation does not converge to the stopping criteria.

The keyword is given without closing “/”


Example: *VERS 1

Keyword *LDIM

This keyword is used if there are pipes to be dimensioned with criteria other than

the ones used in global dimensioning, which is described under the keyword

*DIAM.

FORMAT:

*LDIM <“ledningsid”, krit1, krit2, LIM, sida>

Where:

“ledningsid”: The name of the pipe to be dimensioned.

krit1: Max. permitted velocity in m/s.

krit2: Maximum permitted gradient in Pa/m.

LIM: The pipe diameter in mm below which the velocity criterion is

to

be applied and above which the gradient is to be applied.

sida: Is the same as *, 1 or 2 depending on whether both the supply

pipe and

the return pipe, only the supply pipe or only the return pipe is

to be dimensioned.

Note that when this keyword is used, the pipes in question are dimensioned

using the specified pipe types under the *DIAM keyword. If only velocity is to

be used, krit2 and LIM must be equal to 9.9999E+30 or “*”. Similarly, if only

the gradient criterion is to be used, krit1 and LIM must be equal to 9.9999E+30

or “*”.

There is no limit on the number of pipes that can be dimensioned.

Keyword *NODE

The keyword *NODE is used to enter node data.

If a value is unknown, * or 9.9999E+30 is specified.

FORMAT:

*NODE < Nodeid, ntyp, xkoord, ykoord, elevation, flöde, effekt, pframl,

preturl, dp, tinl, tframl, tretur, dt, lambda1, lambda2, pris1

pris2, pris3, pris4> /

Where:

Nodeid : node identification (-)

Ntyp : node type, an integer in the range 1 to 10.

Xkoord : x coordinate (m)

Ykoord : y coordinate (m)

Elevation : node level (m)

Flöde : flow volume through the node (kg/s)

Effekt : power (kW)

Pframl : pressure, supply pipe (kPa)

Preturl : pressure, return pipe (kPa)

Dp : differential pressure (kPa)

Tinl : inlet temperature in supply pipe (C)

Tframl : mixed temperature in supply pipe (C)

Treturl : return temperature (C)

Dt : cooling (C)

lambda1 : reference value for thermostatic bypass (bypass) (C)

lambda2 : diameter for fixed bypass (mm)

pris1: : production price (SEK/kWh). If no production price is to be

specified, type just a /

pris2 : COx, Environmental charges. Price per kWh produced.

pris3 : NOx, Environmental charges. Price per kWh produced.

pris4 : SOx, Environmental charges. Price per kWh produced.

If a node includes a bypass, min, power = 0 must be set in the node (no

cooling/return temp.) for the bypass to be exported to the calculation file.

Example: *NODE

Name : “NODE01”

Node type : 1

X coordinate : 193.23 m

Y coordinate : 201.53 m

Elevation : 22.5 m

Flow : * kg/s

Power : 12.3 kW

Pressure supply pipe : * kPa

Pressure return pipe : * kPa

Differential pressure : * kPa

Supply temperature : * C

Supply pipe temperature : * C

Return pipe temperature : * C

Cooling : 15.9 C

Reference value temperature : * C

Bypass diameter : 10.0 mm

Production price : 0.70 SEK/kWh

COx Price : 1.00 SEK/kWh

NOx Price : 1.00 SEK/kWh

SOx Price : 1.00 SEK/kWh

Keyword *PFAC

This keyword is used for calibration of the pressure losses in the network.

FORMAT:

*PFAC <fac1, fac2>

where the correction factor multiplied by the normal friction pressure loss in the

pipe is:

correction factor = fac1 + fac2 *Diameter(i) m

Where:

fac1 : Constant

fac2 : Constant

If *PFAC is not specified, the defaults are:

fac1 = 1.0

fac2 = 0.0

Example: *PFAC

Constant term: 1.05

Diameter dep. term: 0.31

Keyword *PIPE

The keyword *PIPE is used to enter pipe data.

If any data for the keyword is unknown, * or 9.9999E+30 must be used.

FORMAT:

*PIPE < ledningsid, Node1, Node2, ledningstyp,

………diam1, u1, ε1, z1, längd1

diam2, u2, ε2, z 2, längd2,


………flöde, dpNode1f, dpNode2f, dpNode1r, dpNode2r, pNode1f, pNode2f,

……… pNode1r, pNode2r, dtNode1f, dtNode2f, dtNode1r, dtNode2r, tNode1f,

………tNode2f, tNode1r, tNode2r, /

xn, yn,> /

Where:

ledningsid : pipe name (-)

Node1 : node name 1 (-)

Node2 : node name 2 (-)

ledningstyp : from pipe type directory

diam1 : internal diameter (mm) supply

u1 : total heat transmission coefficient (W/mK) supply

ε 1 : pipe roughness (mm) supply

z 1 : individual pressure loss in the pipe (-) supply

längd1 : length of supply pipe (m)

diam2 : internal diameter (mm) return

u12 : total heat transmission coefficient (W/mK) return

ε 2 : pipe roughness (mm) return

z 2 : individual pressure loss in the pipe (-) return

längd2 : length of return pipe (m)

flöde : mass flow (kg/s)

dpnode1f : change of the pressure in node 1 supply (kPa)

dpnode2f : change of the pressure in node 2 supply (kPa)

dpnode1r : change of the pressure in node 1 return (kPa)

dpnode2r : change of the pressure in node 2 return (kPa)

pnode1f : pressure in node 1 supply (kPa)

pnode2f : pressure in node 2 supply (kPa)

pnode1r : pressure in node 1 return (kPa)

pnode2r : pressure in node 2 return (kPa)

dtnode1f : DT in node 1 supply (C)

dtnode2f : DT in node 2 supply (C)

dtnode1r : DT in node 1 return (C)

dtnode2r : DT in node 2 return (C)

tnode1f : temperature in node 1 supply (C)

tnode2f : temperature in node 2 supply (C)

tnode1r : temperature in node 1 return (C)

tnode2r : temperature in node 2 return (C)

xn : x coordinate for breakpoint (m)

yn : y coordinate for breakpoint (m)

A / slash must be typed after tNode2r. After that, up to 100 pairs of coordinates

can be specified for the pipe's breakpoints. Breakpoint coordinates are

terminated with a / slash.

Example: *PIPE Pipe ID: “L1” Node1: “K1” Node2: “K2”

Diameter U value. Roughness Single-use resistance

Framl 88.9 0.325 0.05 1.5

Returl 88.9 0.300 0.05 1.0

Flow *

Node1 supply Node2 supply Node1 return Node2

return

Pressure changes 0 0 0 0

Pressure * * * *

Pressure changes 0 0 0 0

Temperatures * * * * /

Breakpoint x: 273.00 y: 598.0

Breakpoint x: 299.0 y: 700.8 /

Keyword *PSUP

This keyword is used to define an implicit pressure for a pressure control.

The absolute pressure is entered as an arbitrary constant pressure. The constant is

a certain element of the differential pressure above the return pressure. The

supply and return pressures are defined in equations:

Ps = Pa + ( 1 - x) * Pd

Pr = Pa - x * Pd

where Ps: Supply pipe pressure

Pr: Return pipe pressure

Pd: Differential pressure

Pa: Arbitrary constant defined by the user.

X: Fraction

FORMAT:

*PSUP <Pres, frak

Pres: Constant

Frak: Proportion of the differential pressure above the return

pressure.

Example: *PSUP

Constant pressure: 1500 kPa

Fraction: .2

Keyword *PUMP

This keyword is used to enter pump data.

FORMAT:

*PUMP <pipeID, sida, naf, nar, pris1, pris 2, pris3,pris4, ndef, flödei, dpi, efi, >/

i = 1 - 12, i.e. up to 12 points can be specified.

Where:

pipeID : Pipe or node ID

sida : 0 both supply pipe and return pipe

1 supply

2 return

3 node

naf : Current speed for the supply pipe (revs per sec)

nar : Current speed for the return pipe (revs per sec)

pris1 : Operating cost for the pump (SEK/kWh)

pris2 : C tax (SEK/kWh)

pris3 : N tax (SEK/kWh)

pris4 : S tax (SEK/kWh)

ndef : Speed for which the pump characteristic is specified (revs per

sec)

flödei : Mass flow at which the pump pressurises dpi (kg/s)

dpi : Pressure increase (kPa), corresponding to flödei

efi : Power (kW), corresponding to flödei

Example:


*PUMP Pipe ID : “L1”

Supply/return : 2

Curr. speed supply pipe : 0 revs per sec

Curr. speed return pipe : 25 revs per sec

Pump cost : 0.70 SEK/kWh

C-tax : 0.4

N-tax : 0.2

S-tax : 0.8

Pump characteristic defined for : 24 revs per sec

Flow Lift Power

0.0 400.0 20.0

75.0 370.0 30.0

125.0 300.0 60.0 /

Keyword *PQTA This keyword administers the distribution of lift between the pumping performed

in the same pipe in both supply and return side and located in the same end of

the pipe. The total lift must be determined by a boundary condition, pressure in

the supply / return pipe or pressure differential in a node in the model where the

pumping has authority. The keyword is placed after the key words * PIPE in the

calculation file.

FORMAT:

*PQTA ”pipeid” Quota /

Pipeid: Pipe identification

Quota: Proportion in % (integer) of the total lift taken by the supply

pump. The rest, (100 – Quota) is taken by the return pump.

Quota must be in the range of 1-99.

Example:

*PQTA ”F4-F5” 50 /

*PQTA ”F7-F8” 70 /

Keyword *SHNT

This keyword is used to describe a shunt valve.

FORMAT:

*SHNT <Nodeid, Tshnt> /

Nodeid : node identification (-)

Tshnt : Required temperature

Note that if the node is provided with a shunt valve device, no other devices are

permitted in the node (e.g. a bypass).

As there is a node reference under the *SHNT keyword, this must be specified

after the *NODE keyword.

Even a requested supply pipe temperature cannot always be obtained. If e.g.

Tshnt = 100°C and max. temperature in the network is 90°C. In these cases, a

warning is issued.

Keyword *STEA

This keyword is used when the medium in the supply pipe is steam and there is

water in the return pipe (liquid phase).

FORMAT:

*STEA

This keyword has no arguments.

Keyword *STOP

This keyword must be entered last in the file in order to make it clear that there

is no further input data. After this keywords, the input data file is closed and

calculation begins.

FORMAT:

*STOP

Keyword *TEMP

When the keyword *TEMP is entered, it is assumed that there is a constant

ambient temperature which is applicable to the entire network.

FORMAT:

*TEMP <omgivn.temp>

Where:

omgivn temp.: constant ambient temperature.(C)

If there are any deviating temperatures in the network, use the keyword *ATMP.

Example: *TEMP Out. temperature: 5 degrees

Keyword *TITL

*TITL is used to place a header in the printout of results.

FORMAT:

*TITL <rad1>

<rad2>

-

<rad20>

Where:

rad : Max. 70 characters per row in the header.

Max. 20 text rows can be specified in the header. If fewer rows are specified, the

final row must end with a / (“slash”).

Example: *TITL “ Network option 1 ”

“ 090919/DV ”

“ ” /

Keyword *VALV

This keyword is used to enter data for pressure-regulating valves.

FORMAT:

*VALV <ledningsid, sida, alfa, alfa1, kv1, alfa2, kv2,....., alfa10, kv10> /

Where:

ledningsid : Pipe identification (-)

sida : 0 both supply and return


1 supply

2 return

alfa : Valve opening degree (degrees) (0 = closed valve)

alfa1 : Valve position (degrees)

kv1 : Valve coefficient ((t/h)/bar½) (belongs to alfa1)

.

.

alfa10 : Valve position (degrees)

kv10 : Valve coefficient (belongs to alfa10)

Up to 10 data pairs of valve positions and valve coefficients can be entered. The

table must be specified with decreasing valve position values.

If fewer than 10 data pairs are specified, the table must be ended with a “/”

(slash).

Example: *VALV

Pipe ID : “R1”

Supply pipe : 1

Valve characteristic:

Alfa Kv

90 360

75 320

60 280

45 240

30 200

15 160 /

Keyword *DYNP

This keyword is used to create input data from a stationary calculation in NetSim

to a dynamic calculation by the network. When keywords are entered in the DAT

file, results file is created with the extension .sss. The SSS file contains

geometry, pipe types and the ratio in the stationary calculation to pressure and

flows in the pipe network.

FORMAT:

*DYNP <DynOpt>

Where:

DynOpt is an integer which defines which part of the pipe network must be

shown in the SSS file.

- To include the supply pipes, enter 1

- To include the return pipes, enter 2

If the keyword is omitted, or DynOpt is set to 0 or *, the link will not be enabled.

Otherwise an error message will be generated.

Unit conversion for pressure:

Pressure is given in the SSS file in mvp, while pressure in NetSim's power data

file is given in kPa. To convert the pressures between the units kPa and mvp, the

equation below is used:

p [mvp = p [kPa x 9.81

where p is pressure.

Keyword *YEAR

This keyword is used to describe a series of stationary simulations with different

loads and durations. This results in an accumulated heat consumption, heat

production and operating costs for heat production and pump operation.

FORMAT:

*YEAR <dur1, tmp1 ....durN, tmpN

fq1(1), fdt1(1), ti1(1), rt1(1), pr1(1)

fq2(1), fdtN(1), tiN(1), rtN(2),prN(1)

.

.

fq1(M), fdt1(M), ti1(M), rt1(M), pr1(M)

fq2(M), fdtN(M), tiN(M), rtN(M), prN(M)

Where:

durM : Duration in hours, the N:th period.

TmpN : Ground temperature in ? C for the N:th period.

fqN(M) : Load factor for node type M applicable to the N:th period.

fdtN(M) : Temperature factor for node type M applicable to the N:th period.

tiN(M) : Inlet temperature for node type M applicable to the N:th period.

rtN(M) : Change in return temperature for node type M applicable to the N:th

period.

prN(M) : Production cost for node type M applicable to the N:th period.

Example: *YEAR

Duration Ground temperature

---------------------------------------

Period_0: 600 h 10 °C

Period_1: 3000 h 20 °C

Period_2: 5000 h 30 °C

/

Node type: 1

Qfaktor DTfaktor Tinl Treturl Pris

----------------------------------------------------------

Period_0: 1.400 1.200 95.00 0.00 1.0

Period_1: 1.000 1.000 85.00 0.00 2.0

Period_2: 0.500 0.900 80.00 0.00 3.0

/

Node type: 2

Qfaktor DTfaktor Tinl Treturl Pris

----------------------------------------------------------

Period_0: 1.000 1.000 90.00 0.00 1.0

Period_1: 1.000 1.000 85.00 0.00 2.0

Period_2: 1.000 1.000 85.00 0.00 3.0

/

/


Time series In an external keyword-based text file, parameters can be specified in order to

execute a dynamic simulation. Keywords are used to control how flow, power

and supply pipe temperature vary over time. The time scale is in the range

minutes to 24 hours. The calculation is executed as a series of stationary

calculations in which the results of every calculation execute input data for the

next calculation, overlaid with the changes indicated by the keywords for the

time series. The interval between calculations is given when calculation begins

(see the section Calculation module). Typically, nodes are allocated consumption

type 1 and the relevant production plants are allocated node types 2 – 10.

In general, the keyword normally begins with a * which is placed in column 1 (at

the far left of the row). Then comes data, always indented by at least 1 position

in the row. Decimal points (.) must be used as decimal separators. This keyword

is ended with the / symbol.

Keyword *QFAC

This keyword controls the given flow for every node type with factors. This

keyword is given for every occurring node type in the calculation. Up to 14

values can be given for time and factor. This keyword is ended with /. Time is

specified with decimals used to indicate part-hours. In the calculation, given

factors are interpolated between given times.

FORMAT:

*QFAC Nodetyp

Tidpunkt1 Faktor

Tidpunkt2 Faktor

...

Tidpunkti Faktor

/

Where:

Nodetyp Node type 1 to 10

Tidpunkt Time (decimal).

Faktor Decimal value by which the specified flow is to be multiplied.

Example: *QFAC Type: 1

0.00 0.82

1.00 0.76

5.50 1.07

7.00 1.26

8.00 1.26

9.00 1.16

12.00 1.01

14.00 0.86

15.00 0.86

16.00 0.98

17.00 1.14

18.00 1.16

19.00 1.14

23.00 0.91

/

Keyword *EFAC

This keyword controls the power for every node type with factors. This keyword

is given for every occurring node type in the calculation. Up to 14 values can be

given for time and factor. This keyword is ended with /. Time is specified with

decimals used to indicate part-hours. In the calculation, given factors are

interpolated between given times.

FORMAT:

*EFAC Type: Nodetyp

Tidpunkt1 Faktor

Tidpunkt2 Faktor

...

Tidpunkti Faktor

/

Where:



Faktor Decimal value by which the specified power is to be

multiplied.

Example: *EFAC Type: 1

0.00 0.82

1.00 0.76

5.50 1.07

7.00 1.26

8.00 1.26

9.00 1.16

12.00 1.01

14.00 0.86

15.00 0.86

16.00 0.98

17.00 1.14

18.00 1.16

19.00 1.14

23.00 0.91

/

Keyword *TINL

This keyword is used to control supply pipe temperature from production plants

for every node type. This keyword is given for every occurring node type in the

calculation. Up to 14 values can be given for time and temperature. This

keyword is ended with /. Time is specified with decimals used to indicate part-

hours. In the calculation, given temperatures are interpolated between given

times.

FORMAT:

*TINL Typ:Nodetyp

Tidpunkt1 Temperatur

Tidpunkt2 Temperatur

...

Tidpunkti Temperatur

/

Where:



Temperatur Supply pipe temperature.

Example:


* TINL Typ: 1

0.00 100.0

1.00 100.0

5.50 110.0

7.00 115.0

8.00 110.0

9.00 110.0

12.00 100.0

14.00 100.0

15.00 100.0

16.00 100.0

17.00 100.0

18.00 100.0

19.00 100.0

23.00 100.0

/

Keyword *OFAC

This keyword controls production costs for every node type with factors. This

keyword is given for every occurring node type in the calculation. Up to 14

values can be given for time and factor. This keyword is ended with /. Time is

specified with decimals used to indicate part-hours. In the calculation, given

factors are interpolated between given times.

FORMAT:

*OFAC Typ:Nodetyp

Tidpunkt1 Faktor

Tidpunkt2 Faktor

...

Tidpunkti Faktor

/

Where:



Faktor Decimal value by which the specified production cost is to be

multiplied.

Example: *OFAC Typ: 1

0.00 0.80

5.00 0.80

5.50 1.00

19.00 1.00

23.00 0.80

/

Keyword *OUTP

This keyword is used to control the print level to the OUT file from the

calculation.

FORMAT:

*OUTP Tidpunkt1 Utskriftsnivå

Tidpunkt2 Utskriftsnivå

...

Tidpunkti Utskriftsnivå

/

Where:


Utskriftslevel 0 = No printout.

1 = Summary printout only.

2 = Complete printout.

Example: *OUTP

0.00 0

5.00 0

6.50 2

7.00 1

12.00 0

/

In the example, there is no printout up to 06.30. A complete printout takes place

between 06.30 and 07.00. A summary printout takes place from 07.00 to 12.00.

No printout takes place after 12.00.


Error messages In general, errors during calculation originate from incorrectly defined boundary

conditions for the calculation. Study the keywords which give rise to the error

message, and study the section on basic elements and properties.

As a rule, the name of the node(s)/pipe(s) which generated the error are shown in

the message.

Error messages generated when the calculation module was inputting keywords

are saved to a log file. This file shows row numbers for rows which generated

errors.

Message Action

*** WARNING *** Both keywords: *FORW and *PSUP used Change input data

*** WARNING *** Energy cannot be extracted from accumulator The accumulator is empty! Change

in node: XX because minimum temperature has been reached. Calculation criteria

*** WARNING *** Energy cannot be stored in accumulator The accumulator is empty! Change

in node: XX because maximum temperature has been reached. Calculation criteria

*** ERROR *** Missing default type in table Change to other Default pipe type

Execution stopped due to input error. a ? in the calculation formula.

*** WARNING *** Heat capacity of accumulator in node: XX Change calculation criteria

has been violated.

*** WARNING *** Inlet temperature at node: XX on supply side Change input data

cannot be calculated.

*** WARNING *** Temperature specification not permitted Check data for bypass

in the same node!

*** WARNING *** Outlet temperature at node: XX – Check boundary conditions

Too many temperatures specified.

*** WARNING *** Temperature at node: XX – Check boundary conditions


*** WARNING *** Temperature in pipe: XX – Check boundary conditions


*** WARNING *** Temperature in pipe: XX – Change input data

too many inlet temperatures specified

*** WARNING *** To many producers Reduce number of production plants

*** WARNING *** Too many flows specified Change input data, check that only one

production plant has an unknown flow

*** WARNING *** Too many temp. specified in node: XX Check boundary conditions

*** Warning *** Blind end in critical route! Suppressed due to the fact that the

route is

“circulating”

“CUBER” Number of iterations exceeded Too many loops in the model!

Accumulator AND bypass in the same node is not allowed. Change input data

Accumulator not possible with steam Correct type of calculation?

Ambient temperature missing. Enter ambient temperature

Bypass is not allowed with steam Change input data

CBRKFF too many iterations Change so that pipe type ? is not

The arithmetical operation caused wastage approved for dimensioning

Criteria for optimization missing! Correct input data for pipe

dimensioning

DP is specified at both ends. Correct input data

Data missing Correct input data

Data missing Correct input data for pipe

dimensioning

Data missing for pipe XX Correct input data for the pipe

Diameter in pipe XX is known The pipe already has a dimension,

delete dimensioning criteria for the

pipe

Elevation not found Change input data

External temperature missing. Enter ambient temperature

Flow cannot be distributed Consequential error, check boundary

conditions

Flow in pipe X-Y between X and Y unknown Consequential error, check boundary

conditions

Flow is specified in node with accumulator with unknown power. Change input data

Illegal data input Correct input data for pipe

dimensioning

Illegal data input for pipe Correct input data for pipe

dimensioning

Incorrect pressure Correct input data

Incorrect temperature Correct input data

Incorrect velocity. Correct input data

Invalid node type! Correct input data

This keyword: XX unknown Correct input data

Length of pipe: XX unknown Pipe length missing, enter length


Max no. of nodes is exceeded Contact Vitec or reduce number of

nodes in the model.

Maximum no. of heaters exceeded. Reduce number of heat exchangers

Maximum no. of valves exceeded. Reduce number of valves

Minimum 1 line of text must be specified Header must not be empty!

Missing data Correct input data

Missing data in pipe table! Correct input data for pipe

dimensioning

Missing default type in pipe table! Change input data for pipe

dimensioning

Neither supply nor return pipe has been specified for pipe Change input data for pipe

dimensioning

No flow in pipe the heater should be turned off. Change input data

No pump in node: XX Pump is defined but the node's input

data is not complete

No pump in pipe Pump is defined but the pipe's input


No solution obtained Check boundary conditions

No valve in pipe XX Valve is defined but the pipe's input


Node XX is not connected to pipes Connect the node to a pipe or remove

the node

Node given under *ACCU does not exist Change input data

Node given under *SHUNT does not exist. Correct input data

Node name: XX unknown! Reference has been made to a node

which is not defined

Node: is duplicated. Correct input data

PRSADM: Pressure cannot be distributed Check boundary conditions

Pipe XX is unknown Reference has been made to a pipe


Pipe name: XX unknown! Reference has been made to a pipe


Pipe: XX is duplicated. Correct input data

Producer node has a bypass. That is not allowed. Correct input data

Pump in pipe X-Y cannot be placed correctly Change placement of the pump !

Shunt AND bypass in the same node is not allowed. Correct input data

Temp. cannot be calculated Check boundary conditions

Temp. cannot be distributed. Check boundary conditions

Temperature change in node must not be zero. Correct input data

Temperature in pipe: XX is unknown Check boundary conditions

The critical route is suppressed due to too many nodes. Critical route is too long

Too many accumulators Reduce number!

Too many local dimension criteria Correct input data

Too many loops Too many loops in model!

Too many pipes in loops Reduce number of loops in model!

Too many shunt valves. Reduce number of shunts

Unexpected End of Input File Does *STOP appear in the right place

in the file?

Check input data.

Unknown keyword(s) in input file! Unknown keyword!

Velocity must be specified. Correct input data for pipe

dimensioning

Wrong data Change input data for pipe

dimensioning

Wrong data (pipe end) Check data for heat exchanger

Wrong data (supply/return pipe) Check data for heat exchanger

Wrong input of maximum and minimum temperatures Change input data

Wrong input of mean temperature Change input data

Missing data (Flow Factors) Correct file licheat.cf1

Incorrect no. of data (Flow Factors) Correct file licheat.cf1

Missing data (Power Factors) Correct file licheat.cf1

Incorrect no. of data (Power Factors) Correct file licheat.cf1

Missing data (Inlet Temp.) Correct file licheat.cf1

Incorrect no. of data (Inlet Temp.) Correct file licheat.cf1

Type unknown! Correct file licheat.cf1

Missing data (Output) Correct file licheat.cf1

Incorrect no. of data (Output) Correct file licheat.cf1

Type unknown! Correct file licheat.cf1


Missing data (Prices) Correct file licheat.cf1

Incorrect no. of data (Prices) Correct file licheat.cf1

No data in Cf1 file Correct file licheat.cf1

CF1 file missing! No CF1 file specified

Dynamic temperatures missing. They must be in the CF1 file. Correct in file licheat.cf1

Mathematical and physical basics

Calculation procedure

Input data

All data needed for the calculation is described in the input data file. This file is

created from the model database in NetSim or directly by the user using a text

editor. When carrying out calculation using correct input data, the program will

undergo the following phases:

The input data file is input. If errors occur during the input procedure,

the error messages will be displayed on screen, as well as in a log file

with the file extension CHK.

Input data is checked on the basis of several different criteria.

The ring connections in the pipe network are registered and the

foundation for the iterative calculation procedure is optimised.

The hydraulic and thermal solutions are found by means of an iterative

procedure.

Results from the calculation are written to the results files.

Pressure

When the flow is known as all points, the pressure loss depending on friction can

be calculated. The pressure loss as a consequence of friction is calculated using

the following formula:

ud zzg

D

LvDKKP

2

21

2

If there is an individual pressure loss in the pipe, this is calculated as follows:

2

2vP

Where:

ΔP = Pressure [Pa

ρ = Density [kg/m³

L = Pipe length [m

Doc-To-Help Standard Template Mathematical and physical basics 109

λ = Friction factor [ -

D = Internal diameter of pipe [m

v = Flow rate [m/s

g = Gravitation constant [m/s² zd = Level downstream [m/s

zu = Level upstream [m/s

ξ = Individual pressure loss coefficient

K1 = Calibration factor 1

K2 = Calibration factor 2 [ m-1

The total pressure loss is the sum of pressure loss due to friction and individual

pressure losses.

The friction factor is calculated on the basis of the Colebrook and White

formula:

Re

413.1

7.3log4

110

D

Where:

vDRe

k = Roughness in the pipe [m

Re = Reynolds number [ -

µ = Viscosity [kg/(ms)

D = Internal diameter of pipe [m

For small Reynolds numbers (< 2300), the friction factor is calculated as:

Re

16

If a valve or pump is placed at the end of the pipe, this is incorporated in the

pressure loss calculation. The pressure loss or pressure increase is added directly

to the pressure at the pipe end.

Temperature

When the flow throughout the entire network is known, the temperature in the

network can be calculated.

The cooling at a consumer can be described as follows if the heat power is

known:

PCQ

ET

Where:

E = given heat power [W

CP = thermal capacitivity of the water [J/kg/C

Q = mass flow [kg/s

The outlet temperature in a pipe is calculated on the basis of the following

expression:

LKU

d eK

MT

K

MT

Where:

QC

CK

P

h

Y

P

ud TKLC

zzgM

Where:

Ch = total heat transfer coefficient [W/m/C

CP = 4190 [J/kg/C

Valves and pumps

A pressure change can be specified at either the upstream or the downstream end

of a pipe. These changes can be described as fixed pressure drops, fixed pressure

increases or as a function of the mass flow in the pipe.

Only a valve or a pump can be specified in a pipe.

For a pump, the current pressure is calculated on the basis of the expression

below:

QBAP 2

Where:

A, B are constants determined through interpolation between relevant reference

values (ΔQ,Q) in the pump characteristic.

Q = mass flow in the pipe [kg/s

η = efficiency of pump

For valves, the pressure reduction is calculated according to the following

formula:

2

610296.1vK

QP

Where:

Q = Flow [l/s

Kv = Valve coefficient [t/h/√mwc

Bypasses

Bypasses can be placed in nodes.

The mass flow in the bypass is calculated using the following expression:

8.3

2

4

2 PDo

Where:

ΔP = differential pressure.

The bypass is viewed as an individual pressure loss with a pressure loss

coefficient of 3.8 and a known pressure loss corresponding to the differential

pressure in the node.

Doc-To-Help Standard Template Mathematical and physical basics 111

Density and viscosity

The program calculates the current density and viscosity, corrected for pressure

and temperature as per the following expression:

0

0

0

TTK

PP

eeDensitet

0

0

TTeViskositet

Where:

P = Absolute pressure [N/m2

P0 = Reference pressure = 0.1013 x 106 [N/m2

K = Bulk module = 2.1 x 109 [N/m2

T = Current temperature [K

T0 = Reference temperature 323.0 [ K

ρ0 = Reference density = 988 [kg/m3

Ґ0 = Reference viscosity = 0.00055 [kg/s/m)

α = Constant = -0.0139 [K-1

β = Constant = -5.47 x 10-4

Keyword *COOL introduces constants to the program which are suitable for the

temperature range < 20 °C.

Steam module

The steam module requires steam throughout the entire supply pipe system and

liquid throughout the entire return pipe system. Latent heat and compressibility

have been taken into account in the calculation. The thermodynamic properties

are calculated on the basis of the equation below:

TRZ

MPtp

,

Where:

P is pressure

M molar weight of the water

Z supercompressibility

R universal gas constant

T absolute temperature

Compressibility is calculated as a function of pressure and temperature using the

SRK equation:

0,,, 23 TPcZTPbZTPaZ

Where a, b and c are a function of pressure and temperature only.

Thermal capacitivity is calculated using:

32 TDTCTBACp

Where:

A = 1791.5

B = 0.107

C = 0.586 x 10-3

D = -0.2 x 10-6

Shunt valve

A shunt valve is placed in a node where water should be able to pass from the

return pipe to the supply pipe. The supply pipe temperature is used to regulate

the flow, i.e. the flow through the valve is selected so as to meet supply

requirements.

The size of the shunt flow, Qs, is calculated from:

*T

QQ

TQTQ

i

si

i

rsii

Where:

T* is the required supply temperature.

Tr is the return temperature.

Qi is the supply pipe flow in the node.

Note that there are cases in which the requested supply pipe temperature cannot

be reached. The programs issues warnings in these cases.

Accumulators

Accumulators are handled as follows:

If the flow is positive in the node with the accumulator (power is stored in the

accumulator), the temperature in the return part of the network, Tr, will be the

same as the minimum temperature for the accumulator, Tmin.

If the flow is negative in the node with the accumulator (power is recovered from

the accumulator), the temperature in the supply pipe part of the network, Tf, will

be equal to the max. temperature for the accumulator, Tmax.

If the accumulator power is known and the accumulator's average temperature

falls below Tmin, it will not be possible to recover energy from the accumulator

in the next time step. Similarly, if the temperature is above Tmax, it will not be

possible to store any energy in the accumulator in the following time step.

Doc-To-Help Standard Template Pipe types 113

Pipe types

Examples of pipe types Below are some suggestions for designations and properties for common pipe

types in district heating networks. The type ? with an internal diameter of 0 mm

is used for pipes which are to be dimensioned. A roughness of 0.1 mm means a

pressure loss which includes the normal losses occurring at bends and branches

in district heating networks. It is necessary to consider using “smoother” pipes

for long transitional pipes.

Doc-To-Help Standard Template Pipe types 115

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