Final Design Report Rev 1 - Residential Wastewater Heat … · 2012-04-05 · Team Flüggen –...
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Team Flüggen
Residential Wastewater Heat Recovery
Final Design Report
Memorial University of Newfoundland
Engineering 8936: Mechanical Project II
Course Instructor: Andy Fisher
Project Supervisor: Dr. Steve Bruneau
Team Members:
Steve Rumbolt – 200636090
Ben Reinhart – 200624435
Andrew McCabe – 200537488
Chris Dawe - 200421873
April 5th
, 2012
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Table of Contents
1.0 Executive Summary .................................................................................................................................... 2
2.0 Project Scope ............................................................................................................................................... 3
3.0 Background Research ................................................................................................................................. 4
4.0 Concept Selection Process ........................................................................................................................ 6
5.0 Final Design Concept .................................................................................................................................. 8
6.0 Theoretical Calculations ......................................................................................................................... 11
7.0 Detailed Design ........................................................................................................................................ 18
8.0 Model Construction ................................................................................................................................. 21
9.0 Model Testing ........................................................................................................................................... 26
10.0 Energy Savings .......................................................................................................................................... 32
11.0 Environmental, Health, Safety, Risks and Sustainability .................................................................. 35
12.0 Design Review .......................................................................................................................................... 37
13.0 Design Recommendations...................................................................................................................... 38
14.0 Future Look Ahead .................................................................................................................................. 42
15.0 Conclusions ............................................................................................................................................... 44
16.0 References ................................................................................................................................................. 45
APPENDIX A- Project Schedule ............................................................................................................................ 46
APPENDIX B – Technical Drawing Packages ...................................................................................................... 47
APPENDIX C – Theoretical Calculations.............................................................................................................. 57
APPENDIX D – Design of Experiments ................................................................................................................ 66
APPENDIX E – Testing Results .............................................................................................................................. 69
APPENDIX F – Construction and Testing Pictures ............................................................................................ 95
APPENDIX G – Design Criteria Table ................................................................................................................... 98
APPENDIX H – Screening and Evaluation Matrices ........................................................................................ 101
APPENDIX I – Final Concept Sketches ............................................................................................................... 102
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1.0 Executive Summary
Through the course of our term 8 mechanical engineering project, we designed and tested a
grey water heat recovery device to salvage heat from wastewater typically wasted down the drain. This
project focused on showers, baths, and dishwasher use. These systems produce the highest amount of
waste hot water and therefore were considered in the scope of our project. We focused on the
development of the heat exchanger itself, while assuming other required information about our system.
To commence the project we performed in-depth research of our design idea searching for information
about current products and anticipated energy savings.
Through concept generation, discussion and refinement, a final concept design was established.
This design incorporated as many desirable features as possible to ensure the successful operation of
the device. Our final concept was a modular setup with each module consisting of a wastewater
reservoir and potable water coil immersed in the reservoir. This design proved to be a very effective
method of increasing boiler feed water.
A theoretical model was generated which analyzed our design concept using the flow conditions
established for our testing procedure. These both produced very comparable results, which further
reinforced the validity of our analysis. On average we saw a 9 ⁰C potable water temperature rise for the
majority of our tests. We originally anticipated a 10⁰C temperature rise, so our proof of concept model
illustrated the design very effectively.
The use of our device would save the end user around $70.00 per year, and while maintaining a
low initial cost the device would pay for itself over the course of several years. We tried to minimize the
costs associated with the device by using a simple design to make this project feasible. The viability of
such a device is dependent on the initial costs.
The final design we suggested incorporates many of the conclusions obtained from theoretical
and testing results. The recommendations section discusses other important project parameters that
would improve the device if further work was to be completed. The health and safety of our device is
described in-depth in the report along with risks and sustainability.
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2.0 Project Scope
The project team intends to design and develop a heat exchanger which facilitates heat transfer
from residential grey water to potable water before it enters a hot water tank. By transferring heat from
grey water to potable water, the team hopes to reduce the energy consumed by the hot water tank
while maintaining the same service level. Also having an increased service life for the end users HWT
should be experienced
The scope of the project is limited to the development of the heat exchanger itself while
assuming that hook-ups to selected devices and the sewer system are available at the final location of
the heat exchanger. The household devices considered to supply grey water to the heat exchanger are
limited to showers, bathtubs, and dishwashers. These devices were chosen as they typically use only
warm. Any auxiliary items that might be designed and optimized later are outside the scope of this
project.
Retrofitting this product into existing homes is outside the scope of this project. The original
idea when beginning this project was to approach building companies and try and integrate this product
into new builds.
The final concept selection can incorporate two distinct heat exchanger modules, a “coil”
module and a “tank” module. Both modules incorporate a grey water reservoir with overspill pipe to
temporarily trap water in the reservoir. The coil module is being designed to perform well during
simultaneous flow conditions, while the tank module is being designed to perform well during
prolonged residency periods. Unfortunately during the design process we were unable to build and test
the tank module, so the team cannot say with confidence that this would be a viable path to go down
for further design considerations. However a modular design was tested with the coil module and we
can say with confidence that the modular design is an improvement to the single module design.
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3.0 Background Research
Residential Greywater Heat Recovery:
A residential greywater heat recovery unit recovers heat from greywater discharged by end use
devices such as; showers, bathtubs, dishwashers, washing machines and sinks by transferring it into
household potable water before entering the hot water heater. The heat is recovered from the
greywater by passing through a heat exchanger where energy is transferred from the greywater to the
potable water.
The typical Canadian family living in a conventional new home uses 65 to 105 gallons of
domestic hot water per day. Heating this water with an electric hot water heater requires 5 000 kWh to
8 000 kWh annually, costing between $500 and $800 dollars per year. All this energy is used to heat
water and then after the water is used it is discharged into the sewer while it still contains much of the
original heat that was put into the water. By using a greywater heat recovery system some of the energy
left in the greywater that is normally wasted may be recovered and remain in the household.
There are many benefits to using a GWHR unit in a residential home as listed below:
- Energy savings and resulting decrease in utility bill.
- Increased first-hour rating of hot water tank.
- Improved comfort to household residents due to decreased hot water temperature degradation.
- Possible reduction in hot water tank volume and increased lifespan of tank.
By preheating the potable water going into the hot water heater there will be a decrease in the
amount of energy required by the heater due to the reduced temperature difference between incoming
water entering the hot water heater and the hot water heater set point temperature. The first hour
rating of a hot water tank is the amount of hot water that may be produced in an hour. This is an
important characteristic of a hot water heater because consumers determine which size/type of tank to
purchase based on this value matching their hot water usage. Using a GWHR unit increases the first-
hour rating of a DHW tank because the tank heats up water faster when the incoming water is
preheated resulting in a greater volume of hot water available from the tank in an hour. By increasing
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the first-hour rating residents will experience increased comfort if they had a problem with running out
of hot water before using a GWHR system and when purchasing a DHW tank it is possible to purchase a
smaller less expensive tank when used with a GWHR system.
Types of Residential Greywater Heat Recovery Systems:
There exist four different types of GWHR systems each with its advantages and disadvantages dictating
the best application:
1. Combined storage tank/heat exchanger that uses conduction and convection to transfer heat
from greywater to potable water.
2. Combined storage tank/heat pump that transfers heat from the potable water to the grey water
using a heat pump.
3. Non-storage type that connects directly to the household wastewater pipe.
4. Point-of-use device that connects directly to an end use device such as a shower and transfers
heat by conduction and convection.
Type 2 GWHR systems are typically used for industrial applications where the system is designed
specifically for its end application. These types of GWHR systems could obtain the greatest efficiency
and heat recovery but because of the cost associated with using a heat pump they are not practical in
residential homes. Type 3 and type 4 GWHR systems are the only types that are currently commercially
available. The products available consist of a 2-4 inch strait copper pipe with 0.5-1 inch copper pipe
wrapped around the exterior of the inner copper pipe. These products are attached directly to the
wastewater pipe to preheat water before entering the DHW tank or at end use device preheating water
before entering that device. Type 2 and 3 GWHR systems are limited by the fact that they can only
recover heat during simultaneous flow situations because there is no storage tank. Type 1 GWHR
systems are possible to be produced at a low cost because there is no heat pump or mechanical parts.
They are capable of recovering more heat than type 3 and 4 because of the use of a storage tank to hold
thermal energy for future use.
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Residential Domestic Hot Water Usage
An important factor dictating the economic viability of a GWHR system is the amount of hot
water consumed by a household. The amount of hot water consumed defines the amount of available
energy to be recovered by a GWHR system. Domestic hot water consumption varies among household
based on; family size, water heater storage capacity, geographic location, energy cost, number and type
of end use devices. There have been studies performed to determine the hot water consumption
patterns of typical households. Environment Canada studied the average water use in Canada and it was
determined that the average person uses 90 gallons of potable water per day. From this 90 gallons 40%
or 36 gallons is used for domestic hot water of which 90% or 32.4 gallons goes to shower use. Therefore
the average Canadian household of 2.5 persons consumes 90 gallons of hot water per day.
During shower use the flow through the GWHR system is simultaneous in that greywater flows
through the heat exchanger at the same rate as potable water. This accounts for 90% of the domestic
hot water use because it occurs during shower use and when using hot water in sinks. The remaining hot
water discharge is batch flow where greywater is discharged while there is no potable water drawn and
at a later time potable water flows through the heat exchanger without greywater flow.
Government Grants
Some government offer grants to residents who use energy efficient devices such as a GWHR
system. The Canadian Federal Government has been offering household energy retrofit grants which
include GWHR systems under the ecoENERGY efficiency grant program. A rebate of 95 dollars is offered
for GWHR systems which have an efficiency of 30-41.9% and 165 dollars is granted for GWHR systems
which have an efficiency of 42% and greater.
4.0 Concept Selection Process
This phase of the project was essential in establishing a model that would perform our desired
goal of recovering wastewater heat. This process initiated with an individual generation of concepts,
which produced a variety of possible ways to recovering this heat. Through group discussion and
concept refinement, we were able to finalize a concept that incorporated many of our design features.
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The process that was used involved generating and refining many concepts. While the inclusion of all the
beneficial design features was essential for a functional device, we had group discussions after every
stage of the selection process. We reanalyzed the concepts and completed several iterations of the
process. Eventually we arrived at a final design concept, which is discussed in the later parts of this
report.
Through the course of the concept selection process we generated a total of 13 different
concepts. To reduce the number of concepts down to the good designs, we used screening and
evaluation matrices to weight the concepts and eliminate the lowest scorers. These matrices are shown
in Appendix-H. The modified screening matrix reduced the number of concepts down to three and the
evaluation matrix analyzed the concepts against our design criteria listed below in the figure below.
Design Criteria Rank
Functionality 4
Sanitation & Safety 4
Cost 4
Size, Weight 3
Volumes of wastewater and potable water 3
Holding/Contact Time 3
Constructability 2
Practicality 2
Filtration/Cleaning 1
Mobility 1
We also added an additional concept which included most of our important criteria, which
ended up as our final selection. The final four concept sketches are listed below and are located in
Appendix - I:
• A – Group Concept 1
• F – Steve R. #1
• L – Ben R. #4
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• M – Group Concept 3
Based on the results from the evaluation matrices, design M (GR-3) turned out to be the best
option as determined when evaluated against our design criteria. The selection of our final concept was
in part due to the results of the evaluation matrix but we also generated this model and included as
many good features as possible so we knew this design would rank high.
5.0 Final Design Concept
The final design concept that we selected consists of a potable water coil in a reservoir of grey
water with an overspill arrangement. We have also designed the system to be modular by adding
additional units in parallel for increased potable water
temperature rise and associated heat transfer. The final
design we selected is illustrated in the figure on the
right. This Solidworks model show a solid view of the
modular design system connected to the desired piping
arrangement for our device. The figure on the following
page shows a cross-sectional view of the model.
For our final concept we wanted to incorporate
as many desirable design features as possible as listed
in our design criteria list below. This list was established
early during the term and helped with establishing a
proper solution to our design problem. Each one of
these categories was discussed and analyzed to include
all the design aspects of our project. The full table of
design criteria and the elements of each are listed in
Appendix - G.
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Design Criteria
- Weight
- Volumes of grey water and potable water
- Reservoir
- Internal tubes
- Hook up
- Solid sediment filtration
- Sanitation control
- Functionality
- Maintainability
- Efficiency
- Simplicity
- Safety Risk
- Environmental Impact
- Cost
- Robustness
- Insulation
After these criteria were discussed in relation to
our final concept, we developed an initial Solidworks
model that illustrated our final design. These preliminary
drawings are located in Appendix B – Initial drawing
package. After theoretical calculations and tests were
performed, we modified our initial final design to include
the results obtained from the design refinement analysis.
These final design drawings are located in Appendix B –
final drawing package.
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The main design features that we deemed necessary for inclusion in our design are:
- Overspill feature
- Greywater reservoir
- Potable water tubes/pipes
- Two layers of separation between greywater and potable water
- No potable water joints exposed to greywater
A list of possible design features that would be beneficial to include but are not essential are:
- Coil with coiled pipe/tubes (Simultaneous flow)
- Multi-stage/Modular design
- Device Emptying
- Solid sediment filtration
- Trap
- Conical shape (ease of emptying)
Our final design incorporates a potable water coil in a grey water reservoir. The coil we designed
for this use is illustrated in the photos below. In order to meet the specification of no joints exposed to
grey water, we have called for one continuous piece of coiled copper entering and exiting from the top
end cap. We have also specified a coating to be used on our coil for two layers of separation and
corrosion resistance. The coiling process produces some internal stresses in the copper tube which
increased the corrosion rate. This coating will be very thin as to not hinder the heat transfer from the
grey water to the potable water.
The modular design that is incorporated in our design can be used to expand the heat recovery
capacity of our GWHR unit. Depending on the average water use or size of the family, the modular
design can be implemented to recover the maximum amount of heat possible. With increased family
size and water use, the amount of water that would pass through our system would still have enough
stored heat in the water that would be cost-effective to recover. The connection of the second unit
would have the grey water pass through in series and the potable water would be connected in parallel.
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With the reduction of potable water flow by one half, the residency time in the device would increase
allowing more time for heat transfer.
We included an overspill feature that is installed between each connecting section to increase
the residency time of the greywater for maximum batch heat transfer. It functions basically like a
reservoir by holding the warm greywater in our device until a new batch of water enters the system. The
grey water inlet drain pipe extends to the bottom of the tank so the warm water pushes out the colder
water. We are also including a manual drain valve on our device for ease of emptying and there will be a
standard trap with valve for maintenance and cleaning purposes.
We decided on two main safety and sanitation specifications to ensure we meet the regulations
associated with potable water standards. The first is two layers of separation between greywater and
potable water. This is going to be accomplished by incorporating at a minimum two layers of separation
between water streams by using either double pipe components, providing a protective coating over the
tube and using a layer of plastic between components. We would also like to incorporate a method to
detect any leaks that would form in the device so that contamination does not occur. Our other safety
feature is to avoid any potable water joints exposed to greywater. To minimize the possibility of water
ingress through fittings, valves, etc., we want to have continuous components through the greywater
sections.
6.0 Theoretical Calculations
Theoretical Modeling
The project team has modeled the heat transfer occurring within the heat recovery device for
several operating conditions considered typical for a residential environment. These operating
conditions are defined below:
• Simultaneous Flow: Potable water and grey water both flowing simultaneously through
the device. The heat recovery device is subject to this condition during warm showers.
The simultaneous flow condition applies for 90% of hot water demand. (Environment
Canada 2004).
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• Potable Only Flow: Potable water flowing through the device with no grey water
flowing. This condition applies when filling a bathtub with warm water or opening a hot
water sink tap. The potable flow only condition applies for 10% of hot water demand.
(Environment Canada 2004).
Other operating conditions exist (such as grey flow but no potable flow) however they are of
little interest. This is due to the fact that the hot water boiler will only benefit from the pre-heating of
the grey water heat recovery unit when there is a hot water demand within the house. Therefore, the
conditions whereby potable water is not flowing through the device are ignored for the modeling.
The thermal circuit for the model is shown below:
Where: Rconv1 is the convection resistance in the flowing potable water,
Rconv2 is the convection resistance in the grey water reservoir,
Rconv3 is the convection resistance in the external environment,
Rcond1 is the conduction resistance in the potable water pipe,
Rcond2 is the conduction resistance in the 2nd layer separation material &
Rcond3 is the conduction resistance in the grey water reservoir.
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The heat exchange in during simultaneous flow is governed by the equation shown below:
(Incropera, p.472)
Where Tm,o is the outlet temperature of the potable water,
T∞ is the temperature of the grey water,
Tm,i is the inlet temperature of the potable water,
m• is the mass flow rate of the potable water,
cp is the specific heat of water (constant, 4184 J/ kg·K), &
U*A is a term accounting for the thermal resistances.
The grey water temperature T∞ is non-constant through time. In order to account for this, an
iterative energy-balance scheme was developed in Microsoft Excel (Appendix C). This allows potable
water outlet temperature Tm,o to be plotted against time. From the thermal circuit, U*A can be
evaluated as:
U*A = 1 / (Rconv1 + Rcond1 + Rcond2 + Rconv2) (Incropera, p.101)
The resistances are dependent upon the materials used and flow conditions within the heat exchanger.
The expected values used for these coefficients are stated below:
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Original:
-Thermal conductivity of copper pipe ‘Kpipe’ = 401 W / (m·K) (Incropera)
-Thermal conductivity of PVC grey water reservoir ‘Kres’ = 0.19 W / (m·K) (Incropera)
-Convection coefficient for potable flow ‘hpot’ = 1631 (W / m2·K) (Appendix C)
-Convection coefficient for grey water flow ‘hgrey,flow’ = 1000 (W/ m2·K)
(me.mtu.edu/~microweb/GRAPH/Intro/film)
-Convection coefficient for idle grey water ‘hgrey,idle’ = 750 (W / m2·K)
(me.mtu.edu/~microweb/GRAPH/Intro/film)
The convection coefficients initially considered were based either on a general ranges of
convection coefficients for given scenarios of an attempted analysis for a similar condition for the coil.
These coefficients were modified such that the theoretical model fitted the experimental data
reasonably well. The experimental data is presented in (Appendix C) while the predicted values
calculation procedure is presented in (Appendix C). Through comparing both data, the following
correction to the initial values of the convection coefficients was observed to provide a better fit:
Revised:
‘hpot’ = 3000 (W / m2·K) (Appendix C)
‘hgrey,flow’ = 900 (W/ m2·K) (Appendix C)
‘hgrey,idle’ = 750 (W / m2·K) (Appendix C)
The revised values for the convection coefficients were a result of a trial and error best fit of
model testing data which is illustrated in appendix C. These coefficients may not provide the best fit for
all scenarios, but for those demonstrated in the lab, this combination performed reasonably well.
Second Layer of Separation Effect
The average values of potable water outlet temperatures predicted for both simultaneous flow
and potable flow only while considering the effect of the second layer of separation are shown in the
next figure for given conditions. This condition is also modeled in Microsoft Excel (Appendix C).
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Given Conditions
Mass of Grey in Reservoir
= 53.20085 kg Volume Reservoir = 530.9L Reservoir
Mass of Pot in Coil = 0.47904 kg Volume Coil = 480mL
Mass Flow Rate Grey = VARIED gpm VARIED
Mass Flow Rate Pot = VARIED gpm VARIED
Initial Temp of Grey = 293.15 K 20 ºC
Initial Temp of Pot = 293.15 K 20 ºC
Incoming Temp Grey = 310.15 K From shower, incoming temp = 37 ºC
Incoming Temp Pot = 280.15 K City supply = 7 ºC
External Temp = 293.15 K Room temperature = 20 ºC
Length of Coil = 6.096 m 20 feet
Req1 = VARIES K/W
=0.005493 for no 2nd layer, 0.007840 for 2
nd layer
(http://www.epoxies.com/therm.htm)
Req2 = 15.822 K/W See Thermal Circuit
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Average Predicted Temperature Rise of Potable Water for
Simultaneous and Potable Only Flows
0
1
2
3
4
5
6
7
8
9
10
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Flow Rate (gpm)
Tem
pera
ture
Ris
e (°C
)
Average Temperature Rise of Potable Water during Simultaneous Flow
Averagre Temperature Rise of Potable Water During Potable Only Flow
Average Temperature Rise of Potable Water for Simultaenoues Flow - 2 layer Separation
Average Temperature Rise of Potable Water for Potable Flow Only - 2 Layers Separation
Average predicted temperature rise of potable water for simultaneous flow and potable flow only
conditions consider both 1 and 2 layers of separation.
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The average temperature rise for the given flow rates considering 90% simultaneous loads
and10% potable only loads are compared for the varying flow rates in the table below.
Average temperature rise reduction due to second layer being considered for multiple flow rates.
The second layer of separation was assumed to be a 1 mm layer of thermally conductive epoxy
(Kepoxy = 2.162 W/ m·K). From the table, a 0.978ºC temperature reduction was seen when introducing the
2nd layer of separation at 1.5 gpm, while a 0.802 ºC drop was seen when analyzing the 2nd layer of
separation for a flow of 2.5gpm. Therefore, an expected temperature rise reduction due to the 2 layer of
separation is expected to be on the order of 1ºC for most typical operating conditions. The value of
energy not recaptured due to the 2nd layer of separation is tabulated below.
Flow
Rate
(gpm)
Average
Temperature
Rise of
Potable
Simultaneous
Flow - 1
Layer (ºC)
Average
Temperature
Rise of
Potable
Simultaneous
Flow - 2
Layers (ºC)
Simultaneous
Difference
(ºC)
Average
Temperature
Rise of
Potable
During
Potable
Only Flow 2
Layers (ºC)
Average
Temperature
Rise of
Potable
During
Potable
Only Flow 1
Layer (ºC)
Pot Only
Difference
(ºC)
Weighted
average temp.
rise 0.9*SimDiff
+0.1*PotOnlyDiff.
1 9.3126 8.2053 1.1074 2.8800 3.2434 0.3635 1.0330
1.5 7.3910 6.3524 1.0386 2.3936 2.8232 0.4297 0.9777
2 6.1131 5.1753 0.9378 2.0357 2.4779 0.4423 0.8882
2.5 5.2086 4.3652 0.8434 1.7674 2.1999 0.4326 0.8023
3 4.5366 3.7746 0.7619 1.5605 1.9747 0.4142 0.7272
3.5 4.0182 3.3254 0.6929 1.3969 1.7899 0.3930 0.6629
4 3.6065 2.9723 0.6342 1.2645 1.6361 0.3717 0.6080
4.5 3.2717 2.6875 0.5842 1.1553 1.5065 0.3512 0.5609
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Control Scenario =4ppl X (10 min shower + 3.43 gpd pot only)
1.5 gpm showers 2.0 gpm showers 2.5 gpm showers
GPD = 73.72 93.72 113.72
delta T = 0.9777 0.8882 0.8023
Cost Savings
(kWH/yr) Reduction
Per Year = 75.2038817 86.85450802 95.19693351
at 10 cents / kWH,
Cost savings
reduction per year
due to 2nd layer = 7.52038817 8.685450802 9.519693351
Average cost savings per year reduction due to considering 2nd layer of separation.
7.0 Detailed Design
The final design the team decided to go with is a modular design. The Reservoirs are fed by
shower water, ideally at a somewhat close range to the module one or two floors up. This will ensure
little losses through the line as the water reaches the device. Water is fed into the first module and fills
it until the coil is surrounded by the incoming grey water flow. The overspill allows for water to pass
from the first module to the second module in a short distance of tubing. The second reservoir, which
operates at a slightly lower temperature, but still has some appreciable heat to recover, is filled after the
first one begins to spill over into it. The second module can either have a coil design or a tank design.
Further design is required for us to say whether or not this would result in more heat transfer, it remains
as a potential idea for future work on the project.
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The Geometry for each module is as follows:
Reservoir Dimensions inches
Outter Diameter 10.79
Inner Diameter 10.00
Height 24.00
End Caps(cut to 10.79") 0.75
Coil Dimensions inches
Height 20.00
Spacing 1.50
Number of coils 16.00
Connectors inches
Overspill 2.00
Inlet pipe 2.00
Drain Valve 0.75
Hose 180.00
The reservoir we had originally sized for this project was too large to get the exact conditions
that we wanted on the inside of the reservoir. If the reservoir was smaller, the equilibrium temperature
would be reached faster and the system would behave more ideally. That is, there would be less of a
build-up curve on the inlet temperature versus time curve when the system is starting up.
For determining the optimum length of copper tubing for the model testing, a mathematical
model was constructed using the heat transfer principles learned in previous courses, and from the
“Introduction to Heat Transfer”-Incopera textbook. The model was constructed in Maple 15, and the
optimization was based on the course material in Yuri Muzychkas Mechanical Systems course the group
is currently taking. The Maple code is attached to this document with all relevant plots and graphs
associated with it. It can clearly be seen, that for the convection coefficient one would expect for the
internal flow of the copper coil, and the convection coefficient expected in the reservoir part, the
optimal length of copper coil came out to be roughly 25ft. This is based off a best case scenario,
assuming a uniform surface temperature on the copper coil, and the water in the reservoir is at peak
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operating temperature (roughly 38 degrees, right after a shower replenishes the reservoir). The model
was solved for the point on the graph where the coil length gave us our ten degree rise we strived for in
the mission statement. This is the temperature rise we feel will make this project economically feasible
based on initial estimates for a ten degree rise. Our group feels that this length of copper will get us the
heat transfer we need to reach our target average outlet temperature of ten degree Celsius.
The potable water lines for the two modules would be split, so the effective flow rate going
through the lines would be cut in half. This would promote heat transfer through both units and we
would expect to see an overall increase in efficiency when operating the unit with module 2 installed.
We were able to prove this theory with our model testing. When compared to the regular 1.5 gal/min
flow rate of a low flow shower head, splitting this in two made the efficiency of the heat exchanger jump
from roughly 30% to 45 or 46%. This is significant to note and will be included in the design
recommendations.
The overspill pipe to the second unit, and the inlet grey water pipe for the first unit both extend
to the bottom of the device, this is so the hot water flowing into the system is forced to the bottom of
the device, and the more buoyant warm water will rise to the top, passing over the coils and transferring
heat as it goes. As a note to improve the design, baffles could be added horizontally in the tank in
between the coils. This would increase the distance of the flow path the grey water must travel in order
to reach the overspill at the top of the device. The turning of the liquid through the channels created by
the baffles will also create a new unique convection environment, where slight eddy currents in the flow
will brush over the coil and increase the effective convection coefficient in the reservoir.
The end caps were made on a lathe in the machine shop. By simply stepping the lid in to the
inner diameter of the reservoir, tight fitting end caps were easily made. These were fitted with holes for
the hose connections.
The stand is incorporated for visual purposes only and was outside the scope of this project to
design, however the model in Solidworks shows what a typical setup like this might look like in an end
users basement. The dual module system would sit in the stand (similar to what the group has shown
here in Solidworks) and would be connected to the houses shower drains and city supply line. The
modules would sit in close vicinity to the HWT to reduce and losses in the lines seen when traveling from
the heat exchanger to the HWT. This might also have positive effects on the reservoir temperature, if
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the line is short enough, hot water from the HWT will egress back into the pipelines in the coil module
due to thermal expansion of the fluid in the HWT, heating the grey water from the inside so that it might
heat the colder potable water behind the hot when an appliance begins to draw hot water again.
Due to unforeseen issues with the coiling operation of the copper tubing we purchased, the final
design coil diameter was increase from 3 inches to 6 inches. This will make coiling efforts a lot easier if
this model were to be reproduced. Also, now that the design calls for two layers of separation with a
coating applied over the entire surface of the coil, the contact between the drain pipe and the coil is
irrelevant because the coil is always surrounded in grey water at all times. The contact between the
drain pipe and the coil was intended to accommodate simultaneous flow loading into the device;
however it was seen in the model testing section of this report that it accommodated both simultaneous
and batch flows quite well, and we were almost able to achieve the heat transfer we had set out as a
target increase in potable water inlet temperature.
8.0 Model Construction
The model construction phase began in early March with the procurement of the materials. The
groups only purchase was 20 ft of copper coil, purchased through Rona located in Kelligrews, NL. In the
plan, the group was to provide a technical drawing package to Technical Services for the coiling
operation by March 12th so that the workers in tech services could know in advance what we wanted to
achieve for our model test. The coil module will be made of ½ inch soft type L copper tubing, coiled over
a 2 foot height and a number of turns somewhere around 15 turns for a 3 inch diameter drain pipe.
These estimates were based off original estimates from the optimization analysis.
The copper coil tubing will be wrapped around the 3 inch copper drain pipe and mounted to the
cover of the GWHRU. The copper coil will be connected with copper connections and routed through
the top end cap as well. Then hoses with hose clamps will be fitted to the copper tubing and also to the
two sink connections.
Shown on the following page are pictures of our constructed model showing the grey water
reservoir and the potable water copper coil.
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The copper coil tubing will be wrapped around the 3 inch copper drain pipe and mounted to the
cover of the GWHRU. The copper coil will be connected with copper connections and routed through
the top end cap as well. Then hoses with hose clamps will be fitted to the copper tubing and also to the
two sink connections.
The reservoir will be made of a pipe we have been given from a father of a group member who
works for the city. The pipe is a 12 inch HDPE pipe and will serve as the grey water reservoir for the
model testing. The bottom will be glued and sealed with silicon to remain leak proof. The end caps will
be made of ¾ inch PVC sheet plastic we purchased through Tech Services for a nominal fee and labour
charge. Technical Services must also prepare to bend the material on the lathe, and will also have
charges for labour associated with the coiling operation. The top end cap of the pipe will have 2 holes
cut to allow connections through to the sink faucets. This end cap will be stepped in on the bottom edge
on the lathe to fit into the inner 12inch diameter. This will not be sealed to allow for easy dismantling.
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The Reservoir will be fitted with an overspill to allow for flow though the unit. The overspill will
be a 2 inch elbow connection drilled into the side of the reservoir; it will be glued and sealed with silicon
to prevent leaking, and to keep it in place testing.
The following vendor list was used for the acquisition of our materials and supplies.
Model Construction Process
First the bottom end cap will be glued into place with contact cement to prepare the water tight
seal. The top end cap will be left un-glued for easy removal. While the glue is drying, the coil must be
prepared and fitted for connections to allow for cold and hot water to be connected from faucets in the
fluids lab. The ends of the copper coil must be widened and made more circular before they can be
fitted with hoses and hose clamps. The hoses will be drawn through the top end cap and left at an
appropriate length for testing.
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The hoses must then be drilled with holes to allow for thermo couple wires to be exposed to the
passing stream of water. A hole must be drilled in the top end cap as well for a thermocouple wire to be
passed through to test the outgoing greywater temperatures. There are a total of 4 testing points, so 4
holes must be drilled.
The bottom end cap will then be dry, so the silicon sealant can be applied to the exterior edge
and the interior surfaces of the end cap, to allow for a perfect water seal given the loading conditions.
Once the silicon has been applied it must be left to dry for a few hours.
At this point, the copper coil must be hydro tested to ensure no leaks are coming from the
potable water lines in the system. Once the sealant is dry on the reservoir, it must be hydro tested as
well to ensure no leaks occur during testing.
The next step in the construction plan would be to cut holes in the reservoir for the overspill
elbow and the drain valve. The drain valve hole is sized at ¾ inch NPT pipe tap, so the hole we cut must
be 29/32 inches in diameter. Once the hole is tapped, plumbers tape is applied to the drain valve and it
is screwed into place. The over spill hole is cut to a slightly larger diameter hole than the overspill elbow,
and is then contact cemented into place, and sealed with silicon to ensure there are no leaks during
testing.
Finally, the taps for testing must be calibrated to 1.5, 2.0 and 2.5 gallons per minute before
testing begins. The mixing tap must be 1.5 gallons per minute as well at 37-42 degrees Celsius (the
average incoming temperature expected from showers), and the cold potable water incoming
temperature is of no significance (that is, the average temperature rise is what the group is after). The
taps are marked off with a marker and flow rates will be verified with a bucket/timer setup, calculating
values in gallons per minute.
Final Model
The material the group had procured for the project was a ½ inch copper tubing type L “soft”
copper. Unfortunately for us, it took a longer than anticipated amount of time for us to procure the
copper tube. Dave Snook in tech services and I inspected the copper when it arrived. By initial inspection
Dave knew the copper was not going to react well to the coiling process. The wall thickness was too
large for the type of bending operation they had planned for the coiling. The copper could not under any
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circumstances go onto the originally designed drain pipe. Therefore the only thing that could be done
was have it applied on a different coil diameter. 6 inches was the new diameter for the coil unit. We
accepted this and the fact that the coils would flatten out to some degree because it would still fit in the
unit and, theoretically you can control the flow through the unit with the cold water tap, the
temperature can be measured and put into our mathematical model.
So, to summarize, the finished model looks exactly the same other than the coil module itself.
The coil will allow for no extra copper to be bent for connection. This leaves the only alternative for this
to be hose connections right in the reservoir itself.
After model testing, the group plans to clean off and grind smooth the exterior of the reservoir
for esthetics. The reservoir will be painted and the company logo will be stenciled on the outer surface.
Colors are to be determined at a later date.
Cost of Model
The model costs included a 20ft length of copper coil which we purchased through Rona, the
charges applied through tech services for the work they performed (cutting 2 end caps for our reservoir
and coiling the copper around a 6 inch pipe). For model testing purposes the project required a few
extra purchases that the group decided to finance for rapid acquisition. The project team bought 15 ft of
garden hose, hose clamps, 6 feet of 2” rubber hose, 3 ft of pvc 2” drain pipe, some PVC cement and
silicon sealant from KENT building supplies.
The bill of materials for the model prototype is seen in the next figure. It can be seen that for
the limited budget we had for this project, we were still able to produce a working model for under the
allotted amount of money. This is good, because the amount of money we expect to save people isn’t
going to be enormous. That means, in order for this project to stay feasible, the overall cost of the
product cannot be too high.
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Bill of Materials
Material Quantity Unit Price Total Cost ($)
Copper Tube 1/2" 20ft 2.26$/ft $51.98
Resevoir for Sheath Comp. 1 ea. DONATION $0.00
Second Reservoir 1 ea. DONATION $0.00
City Water Reservoir 1 ea. DONATION $0.00
Work Space Fluids DONATION $0.00
Tech Services 3 hr 10$/hr $115.00
Miscellaneous 3 ea. 10$ ea. $50.00
$216.98
Note: Actual model cost if price of donation items are included is $256.98
9.0 Model Testing
For the model testing phase we set out to simulate typical household hot water use scenarios
and gauge the effect on energy savings. This involved designing different types of experiments to match
the flow characteristics of two main types of typical residential waste water flow - simultaneous and
batch flow. Simultaneous flow is when potable and grey water are running through the device, which
can be used to model shower and dishwasher operation. This type of flow condition will account for the
majority of hot water use in a typical household and therefore was the main concern for our testing
procedures. The Design of Experiments used for this process is included in Appendix D.
The data acquisition aspect of the testing included modifying the constructed model to include
points of insertion for the temperature monitoring probes. Temperature readers and thermocouples
were used to record the results of our potable and grey water temperature rises. Four main points were
used to measure the temperature rises – potable water in and out and grey water in and out.
Temperature recordings were taken every 30 seconds for each test, so that we could analyze the
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transient aspects and steady state operation. This proved to be ample time for observing the
temperature trends during the operation of our device.
To simulate actual water use in a home a specific scenario was established. This was achieved by
modelling a typical morning water use scenario that consists of three 10 minute showers with two 5
minute breaks. This test was run using different potable water flow rates to simulate different types of
typical shower fixture flow rates. This test produced some very informative results about the amount of
heat transfer associated with using low flow shower fixtures.
We also wanted to test the modular design to determine its efficacy of recovering heat while
still maintaining its feasibility. The multi-stage system design was potable water lines connected in
parallel between the two modules, hence reducing the flow rate by one half. A flow rate of 0.75 gal/min
was used for these tests assuming low flow shower fixtures. The first stage was run using an initial
reservoir temperature of 24 ⁰C and the system was left running for 10 minutes. To achieve a multi-stage
test, the final grey water temperature out of the first test was used as the incoming grey water
temperature of the second test. Considering our overspill feature this water would be flowing into the
second module at the grey water outlet temperature of the first
Batch flow was modelled with only potable water flowing through the device, while holding the
grey water flow at zero. This simulates sink use or a bathtub slosh through the device. We modelled sink
use by setting the tank temperature at room temp and running the potable water. We modelled a
bathtub slosh by raising the tank temperature to 40 ⁰F and running the potable water through the
device.
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The exact listing of performed tests is given below with some detail on each test type:
Potable water and greywater flowing (Shower and Dishwasher)
1. Testing Type 1 – Three 10 minute showers with 5 minute breaks
a. Q = 1.4 gal/min
b. Q = 1.6 gal/min
c. Q = 2.0 gal/min
d. Q = 2.5 gal/min
2. Testing Type 2 – Continuous running for 20 minutes for Q = 2.5 gal/min
3. Testing Type 5 – Decrease reservoir volume
Potable water flow only (Sink use, bathtub slosh)
1. Testing Type 3 – Q = 1.5 gal/min
a. Reservoir temp at room temp
b. Reservoir temp at 40 ⁰C
Multi-stage flow (modular design)
c. Testing Type 4 – Two passes in parallel
i. Flow rates in half, reservoir temp of 2nd test to be at grey water out of first
reservoir
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Testing Results
Based on the tests listed above the average temperature rise and associated efficiencies are
tabulated below.
Test ΔT (⁰C) Efficiency (%)
Typical Morning
Q = 1.4 gal/min 9.85 30%
Q = 1.6 gal/min 8.92 28%
Q = 2.0 gal/min 8.62 24%
Q = 2.5 gal/min 7.68 23%
Multi-Stage Design
1st
stage (Q = 0.75 gal/min) 14.50 43%
2nd
stage (Q = 0.75 gal/min) 11.51 49%
Batch Flow
25⁰C Tank (Q = 1.5 gal/min) 5.43 30%
40⁰C Tank (Q = 1.5 gal/min) 9.75 42%
The results obtained from the tests were very helpful in identifying temperature rise trends
associated with different operation of the device. The full set of testing data and results are included in
Appendix E. Possible model improvements were also identified from the results and incorporated into
our final design. The typical morning scenario produced some very comparable results to the theoretical
model and illustrated a very important relationship between flow rate and heat transfer. The multi-
stage tests also confirmed the feasibility of using a modular arrangement for increased cost savings. The
batch flow tests were also as predicted, with a gradual decrease in temperature rise over time.
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The results of the typical morning hot water use scenario were very beneficial in establishing
design improvements and future prototyping ideas. These results indicated that lower flow rates
produce larger temperature rises. This is intuitive due to the fact that with lower flow rates the
residency time of potable water inside the tubing would increase. In the figure below the temperature
rise for typical morning use is plotted for different flow rates. As evident from the black line on plot
below the lowest flow rate Q = 1.4 gal/min generated the largest temperature differential.
The multi-stage testing results confirmed the feasibility of using multiple modules for homes
with high hot water consumption. Illustrated in the figure below, reducing the flow rate by one half
results in a much larger temperature rise for potable water. In the first stage of operation we see an
average temperature rise of 14.50⁰C which is well above the single module value. In the second stage
we see a 11.51⁰C temperature rise by using the lower greywater inlet temperature. On average, this
produced a temperature rise of 13⁰C, which would result if the lines were to tie back in together. In
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comparison to an average temperature rise for one module operating at the same flow rate of 8.92⁰C,
we see a 4.08⁰C rise using two modules. This result proved that the use of a modular design would only
be beneficial in large families with high hot water demand loads. The initial cost of fabricating an
additional module would have to be weighed against the hot water use to determine payback periods
exactly. Illustrated in the figure below is the average temperature rises for the multi-stage operation in
comparison to the single module operation. As can be seen the multi-stage arrangement produces an
increase of 4⁰C in average temperature rise compared to the use of one module.
The batch flow analysis also produced good results. The temperature rise of the potable water
was much better for the higher internal reservoir temperature of 40⁰C, where it produced an increase of
9.75⁰C. The two plots listed below are indicating the decrease in temperature difference over time for
25⁰C and 40⁰C tank temperatures respectively. As can be seen the 40⁰C plot has a much higher average
temperature rise and the decreasing converging lines would continue out the page for prolonged heat
transfer.
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10.0 Energy Savings
The idea behind making this project economically viable is taking unused hot grey water from
your shower and dishwasher, and using it in a safe and efficient way to transfer heat to the incoming
city water supply going to your hot water boiler. This will result in a jump in the incoming potable water
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temperature, which will put less of a demand on your hot water heating elements (be they electric of
natural gas). It all breaks down into a temperature difference seen at the HWT tank inlet, and a kilo-
watt-hour savings per year and gallons per day water usage, which can be multiplied by roughly ten
cents per kW-hr.
Given the following equation for energy consumption per year, we calculated the energy saved
per year when comparing the usage of our system against the same hot water tank use but with no
temperature rise from a GWHRU.
For an Electric Water Heater:
UECe = (Use * TempRise * SHW * 365) / [3413 * (EF/100)]
UECe = unit energy consumption (kWh/yr)
Use = household hot water use (gallons/day)
TempRise Average temperature rise of incoming potable water (F)
SHW = specific heat of water (8.2928 Btu/gallon-F)
3413 = conversion factor (Btu/kWh)
EF = energy efficiency factor from DOE test procedure (%85 assumed)
The annual savings calculation for a ten degree temperature rise for incoming potable city water
is as follows. Our test home will have 4 showers per day and a dishwasher load every 2 days. With a flow
rate of 1.5gpm and 10 minute shower allowance we deduce that 60 gallons per day can be used to
recover heat to incoming water supply. Also assuming this households hot water tank is set at the
national average of 55 degrees Celsius, and that incoming potable water comes in at the national
average of 11 degrees Celsius (Ontario Power Authority 2003). Under these scenario conditions, we plot
the kwhr savings and the dollar value savings per year after using this device. The graph show the
gallons per day usage increased from 10 to 60 gallons per day, and a jump in dollar value savings from
20$/yr to 120$/yr.
Listed below are plots of theoretical energy and cost savings associated with the device.
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KW-Hr savings per year seen from ideal device:
Cost savings seen from using device per year:
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Model cost savings vs. Theoretical cost savings. This is based on the average temperature rise
seen through experimentation of 9 degrees.
It can be seen that our model did not quite meet the target goal, however we were close. The
drop in cost savings can be seen from the fact that our models coil was flattened out, decreasing the
volume in the coil and increasing the velocity of the fluid passing by. The negative effect is that less heat
transfer occurs due to shorter resonance times. We as a group still feel that we could have achieved our
milestone temperature rise if we had been more equipped for the cold working coiling operation
needed for the success of this project.
11.0 Environmental, Health, Safety, Risks and Sustainability
Health and Safety
The only major safety risk of a GWHR system is the potential contamination of potable water by
greywater. Greywater contains bacteria which would pose a major health risk to residents if it were to
enter the potable water stream. The risk is very low but due to the extreme health risks associated with
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contamination and the fact that a leak could go undetected, it is necessary to use measures to eliminate
this risk. The final design eliminates this risk by:
• Using two layers of material separation between the potable water and greywater streams.
• No potable water joints exposed to greywater.
• Potable water stream at higher pressure than greywater.
Two layers of separation between greywater and potable water are required so that if a leak
where to occur than it would be contained by the second layer. Because a rupture in one of the layers
could go undetected it is necessary to perform an inspection of the potable water coil periodically to
ensure both layers are intact. The copper potable water coil in our final design would be made entirely
out of one length of copper so that there would be no connections exposed to greywater. This reduces
the possibility of a leak occurring by eliminating connections which have a much greater chance of
leaking than the pipe itself. The greywater in the final GWHR system design is at atmospheric pressure
and the potable water stream is at the city water supply pressure therefore if a leak where to occur it
would be from the potable water into the greywater and no contamination would occur. While
performing cleaning and or maintenance on the system the potable water and grey water lines bypass
the GWHR unit causing a situation where the potable water pipes are not pressurized but still
surrounded by greywater until the tank has completely drained. This scenario could allow grey water to
enter the potable water pipes if there where a rupture in both layers of the potable water lines. To avoid
this scenario it is mandatory to keep the potable lines pressurized while the greywater is bypassed and
the tank is completely drained of greywater then the potable water line may be bypassed.
Risk and Sustainability
The Fluggen GWHR system is a sustainable design by default because the purpose of the system
is to reduce household energy consumption. The system is very sustainable due to its long life of at least
ten years. This is achieved because all components are corrosive resistant and there are very little
stresses applied to the device. At the end of its lifetime the Fluggen GWHR system would have a minimal
impact on the environment because the majority of the components could be recycled or reused.
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Environmental
Depending on the method of electricity production the use of a GWHR system will reduce the
amount of carbon dioxide produced. If a natural gas hot water heater is used the reduction in
greenhouse gas emissions is directly proportional to the reduction in the water heaters gross energy
consumption. For every 1 kWh of natural gas consumed produces about 0.0018 tonnes of carbon
dioxide. Therefore based on our model the average family using 32.4 gallons of hot water per day
resulting in 500 kWh per year would reduce their carbon dioxide emissions by 0.9 tonnes. At the high
spectrum of hot water use a household using 60 gallons of hot water per day would reduce their carbon
dioxide emissions by 2.16 tonnes. If using an electric hot water heater where the electricity is coal-
generated a household consuming 32.4 gallons of hot water per day would offset 4.1- 4.85 tonnes of
Carbon Dioxide per year.
12.0 Design Review
The design began slowly and involved a large amount of thorough planning and researching
before a final concept was selected. Once we selected the final concept the team had a rough idea of
what the final design would look like. This was much smaller in scale than the final design you see in this
report today. The second iteration of the design was capable of holding much larger amounts of water.
The pipe we had donated to us was a 12” diameter HDPE sewer pipe. This was the best thing we had
available to us. After testing this model we realized that the volume inside the reservoir was too heavy
to pick up, and we were having trouble with mixing and time to reach equilibrium. The final design today
has a ten inch diameter to fine tune the volume of grey water so that it has a better heat transfer
characteristic. The smaller volume in the tank will be replaced with hot water faster, and the average
temperature in the reservoir will rise faster than that of the 12” diameter reservoir.
In design it is always important to realize where you went wrong after you reflect on what
you’ve done, and determined what goals you set out to accomplish, and whether or not those goals
were satisfied. The group feels that our goal was nearly accomplished. We proved that it is possible to
recover the heat typically lost through shower and dishwasher water and turn it into cost savings and a
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reduction on the demand of the hot water tank. This goal was accomplished, however the group could
have performed certain tasks better and the outcome of this project could have been much greater.
Time management is something the group could have improved on. Getting instrumental
documentation prepared for review on time was proving hard sometimes throughout the term. If a
harder grasp had been taken on following our internal deadlines, the project could have ran a lot
smoother.
13.0 Design Recommendations
Baffles – Baffles are recommended to be installed in horizontal positions along the reservoir
walls. The baffles would be circular in cross section and be made of similar materials. By introducing
baffles to internal grey water flow through the reservoir, increased convection coefficients will be seen
near the coil surface, promoting heat transfer. Not only this, but by making the reservoir path longer for
the grey water, a more even temperature distribution can be seen throughout the reservoir. This will
cause our system to react more ideally to system parameter changes, and we feel, will increase the
average heat transfer seen to the incoming potable water in the coil.
Reduced volume – The model our group constructed was a 12” diameter HDPE sewage pipe. A
similar material is recommended for this device. However, during testing it was noted that for low flow
rates (1.5 gal/min) the mixing of temperature in the reservoir was equilibrating at a much slower rate
than we once predicted. To counteract this ill effect, the reservoir diameter must become 10”. By
reducing the effective volume of the reservoir by 20L, the operating temperature of the device can be
reached more quickly, ensuring that by the end of the first shower in a day’s cycle, the reservoir can be
thought to be operating at its peak temperature, ensuring future results are consistent. It is thought that
the effect of cooling from the copper coil will have a counteracting effect on the overall operating
temperature of the device. The average operating temperature seen in the reservoir should remain
reasonable unchanged after the design change is taken into account. This however would have to be
proven with additional testing.
Permanent connections – Permanent connections leading from the copper tubing should be
installed in an improved prototype. The group had initially intended to do this, however due to the
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unique circumstances with tech services and the coiling operation, no copper was left over for their
fabrication. The copper connections would come from the top and the bottom of the coil. The elbows
would not be so large as to not fit inside the reservoir. The connections would come up through the top
end cap of the reservoir through pre drilled holes. They would be mounted at a set distance and sealed
into the holes so the whole assembly could be lowered in for sealing. The ends of the copper would be
cut short to the reservoir top and soldered connections would be put in place to make this device easy
to install into the home. That is, it fits right in to standard water line connections.
Cover – The cover would be sealed in place after to decrease the heat losses to the
environment. All other places where heat could be lost would be sealed as well.
Coating – A protective coating would have to be applied to the finished product (the coil) after it
is ready to be installed. The coatings could be metallic, paint or an epoxy dip. This would be to ensure
prolonged corrosion protection against the environments the grey water would subject the surface of
the coil to. This would effectively provide the two layers of separation between grey water and the coil,
ensuring no joints are exposed to grey water since the connections would be soldered in place. A
recommended product would be something like Polyamide Epoxy coatings for pipe, ceilings and other
industrial uses. The product description from the manual is this:
This two component epoxy offers excellent impact and abrasion resistance, plus has good acid and alkali
resistance. This product is for use on properly prepared interior & exterior ferrous metal, galvanized
metal, wood, plaster, and masonry and drywall surfaces. Examples include commercial and institutional
walls, ceilings, machinery, piping, cabinets, storage tanks and high traffic floors.
Features
• High gloss extremely durable stain resistant film
• Very good impact and abrasion resistance
• Good acid and chemical resistance
• Very good alkali resistance
• Resists strong cleaning compounds
• Solvent resistant
• Tile like finish does not support mold, mildew, or fungi growth
• Forms a dense, waterproof barrier coat
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This coating is expected to perform quite well under the process conditions outlined in this
report. It would be the first scenario we would test. If it was sufficient we would move on however if for
some reason it failed, another materials would have to be researched and selected. Some benefits of
using an epoxy dip is that it is simple and easy to apply, and a bucket of epoxy is good for coating a large
number of coil modules.
Tank Module – Exploring the idea of a tank module further would be an interesting venture. The
idea behind the tank module is to increase the volume of city water in the reservoir, effectively slowing
the flow rate through the city water tank to very low rates. This would promote a much greater heat
transfer rate to the city water than the coil. The tank would also have to be dipped to ensure 2 layers of
separation between grey water and city water. Additional testing would have to occur for the new
modeled prototype. Some SolidWorks drawings are provided in the appendix for how a tank module
might look. The tank module could be connected in series with a coil module to provide both prolonged
heat transfer from the tank and the immediate heat transfer seen by the coil module during
simultaneous flow operations (showering). Also something worth nothing, by introducing this new
design, it would make fabrication costs increase. The manufacturing plant now would have to have two
sections, one for tank modules and one for coil modules. Where is we kept a simpler design of using two
coil modules in series then the manufacturing of this product would be simpler with less room to make
mistakes.
Testing – Varying system parameters have sometimes costly effects. Having to redo tests is
never an effective way to work. Measures to control flow rates should be implemented for testing. This
test was a rough estimate of what might actually occur in the system, but a more accurate setup, using
the new prototype should be implemented, with a flow regulator used for testing to provide more
accurate results. Permanent temperature testing site could be mounted to the copper inlet tubes and
overspill. This would eliminate leaking due to holes drilled for thermocouple wires. Testing multiple
configurations for the modular design is a good idea. Changing the potable water connection from
parallel to series could have different results, and they are important to note for installation purposes.
Slanted Reservoir Bottom – Having a slanted bottom that ran to the drain valve would ensure all
waste seen from devices is immediately sent down the drain after emptying.
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Servo Valve, Automatic Draining - An idea to reduce the costly marketing effects seen by having
to come and clean the device every so often is to include a self draining mechanism into the unit to
ensure that after peak operating hours, when the reservoir is full. Once the tank temperature reaches
that of the ambient room the valve will open, draining the device entirely straight into the sewer
(through a trap to ensure no sewage air could egress into the home). Some code would have to be
written for the servo valve programming. An overspill feature would still installed for added safety, in
case the servo valve fails to open. If this were to be achieved on a prolonged basis the effects of
maintenance really would disappear. However this introduces a new variable into the mix, the servo
valve would have to the run on electricity. It can be expected that for intermittent use the electrical
costs associated with this would be quite low, however they would have a negative effect on the overall
cost savings of the device. To what degree, it is not known at this time; however it could be evaluated in
a later stage of the design.
Peak Operating Hours – The peak operating hours is defined as the length of time during the day
where the hot water demand is highest. This design is under the assumption that showers are occurring
one after the other, when in actually fact, they very well might not do this. In order for our model to
work most efficiently, the showering needs to occur all around the same time. This is a flaw in the design
in the end of the day. Our model should be able to accommodate any flow characteristic. Increasing the
robustness of the design would be a key goal if this project were to move forward. Anyone taking on this
design challenge in the future should take this into consideration, and put more research and thought
into improving this aspect of the device. (Servo valve idea would have just that effect, the effective
temperature is much high when filling the tank. It would have to be designed in such a way that the tank
filled quickly so that the liquid covers the coil as fast as possible. (This would promote good heat
transfer, faster).
Increasing Coil Diameter - By increasing the coil diameter, the flow can be expected to slow
down through the device. This promotes better heat transfer and should most certainly be explored in
further testing operations. The group, in this situation, would measure the incoming flow rates and
compare the two devices side by side, it would be expected that a greater delta temperature would be
seen in the increase tube diameter prototype. This might have some negative effects on the city water
pipeline; this idea would have to be explored before testing to ensure no damage would come to tying
this prototype into an end users city water supply line.
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14.0 Future Look Ahead
Team Fluggen would like to take this part of the report and discuss a little bit about the possible
way forward from this stage of the design. The team has accomplished a few milestones, like building
and testing our prototype and proving that it can have cost savings in the vicinity of where we wanted
them to be at the end of the day. However, further refinement of the model is required. The look ahead
will be broken down into steps, beginning with:
1) Constructing and testing prototype 2 – The model the group fabricated is functional, however
the connections are not permanent and the copper coil didn’t turn out the way the group had
originally intended it to. The first priority of the group would be to build and test the new model
with refined dimensions. The results from those tests could be compared to the original results
from the current model, and any improvements to the heat transfer characteristic would be
noted, and new cost savings would be calculated.
2) Marketability Study – A marketability study would have to be carried out to assess the market
here in NL, but also across Canada with the use of online surveys. Through this exercise, the
group could possibly attain a volunteer to hook the new refined prototype into their home to
see how the performance measures compared to those results found in the lab.
3) Approach Construction Companies – It would be a mission for Fluggen to approach local and
larger construction companies that design and build houses in urban environments, assess
whether or not a product like this could be easily included into their plumbing blue print
drawings, and determine whether or not companies would be willing to include a device like this
into their building plans.
4) Maintenance Assessment – The maintenance requirements as of right now are ill defined,
because the team did not have an accurate way of simulating this effect with experimentation. If
the new prototype were to be installed into a real home and it had real grey water moving
through it, the maintenance requirements would have to be assessed and a recommended
cleaning schedule could be put forth for the operators manual for the end product (after the
design process is finished).
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Potential Market
Based on the results from the Fluggen model testing the concept has been proven to be
successful when used with a cold inlet water temperature of 6 degrees Celsius. Heat recovery will
decrease with increasing cold water inlet temperature therefore colder regions such as Canada will
experience the greatest energy saving with a GWHR system. In warmer climates GWHR are less effective
and are in competition with solar hot water heating which has been proven to be an effective method of
hot water energy reduction.
Potential markets for the Fluggen GWHR system are as follows:
1. R-2000 houses.
The most obvious market for GWHR systems is R-2000 houses because there owners
and designers already have an interest in energy savings. The R-2000 market is relatively small
however it would serve as starting point to expose the public to GWHR. R-2000 homes are
mainly designed to reduce space heating load while incorporating low flow fixtures and an
energy efficient water heater. The DHW use is low in these houses however the fraction of total
energy used by DHW heating is larger than in the average house.
2. Remote location market.
Remote locations with high energy costs and low potable water temperatures such as
northern Canada are an ideal market for GWHR because of their high energy cost. Domestic hot
water heating is often several times more expensive in these areas therefore the payback
periods for GWHR systems should be very short.
3. Multi-unit residential market.
Condominiums, duplexes and apartment blocks are an excellent application for GWHR systems
if the greywater plumbing is common to more than one home dwelling. With multiple units
draining greywater through the same pipe the total greywater energy available would be much
higher than a single detached house therefore the greater potential energy savings.
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15.0 Conclusions
From this design process, it can be concluded that using a device like the one we produced here
at the university would have beneficial cost savings if used in a residential application. Implementing a
device like this one would also have positive effects on your hot water tank. The reduce load
requirements experienced by the hot water tank would prolong the life of the heating elements (for
electrical applications) and reduced maintenance requirements would be experienced by the end users.
It can also be drawn from this experience that this device can be produced for less than 300 dollars.
Keeping the model inexpensive was a key milestone for this project. It was felt by all group members as
well as the group supervisor that if the model were to have been expensive, it would not be very
marketable. With an expected life ranging from 10-15 years where the system is so passive, it could be
expected that cost savings would pay for the device and then much more for households with higher hot
water demands than seen on average. It can also be concluded that the mathematical model used to
predict these temperature differences is accurate to an acceptable degree. This can ensure that future
design alterations will provide us with accurate information before we move into testing phases.
Some improvements mentioned in the latter part of this report would certainly have to be
included and evaluated in the second round of testing if this project were to be carried further. Also, a
test house would have to be established, whose plumbing would be altered in such a way that this
device could be tested in a real life scenario. A method of observing the cost savings would have to be
created, perhaps by evaluating the power associated with a control house, with the same number of
individuals living in it having similar hot water demands.
It can also be concluded that if this project were to continue forward, a marketability survey
would have to be performed to evaluate the market for introduction of a device like this into someone’s
home. Also, a product like this might not be feasible in other countries like in Europe, where the water
consumption is much lower than that here in Canada. A feasibility study could be done, to see if the on
average higher prices seen in Europe could counterbalance the less favorable heat transfer
characteristics of the water consumption rates.
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16.0 References
1. http://oee.nrcan.gc.ca/equipment/heating/806#storage
2. http://home.howstuffworks.com/water-heater.htm
3. http://www.canadianwaterheaters.com/en/c378144982/index.html
4. http://books.google.ca/books?id=POemMdRJ_qcC&pg=PA537&lpg=PA537&dq=average+dishwa
sher+discharge+volumes&source=bl&ots=b5cDqC-
Moa&sig=G8Gqrlg8EfgpDrQtPJRVK7wB1Qc&hl=en&sa=X&ei=omwhT7WXG-
vp0QGj48GACQ&ved=0CDAQ6AEwAQ#v=onepage&q=average%20dishwasher%20discharge%20
volumes&f=false
5. http://www.practicalenvironmentalist.com/eco-gadgets/dishwashers-energy-star-water-
efficiency-and-the-environment-a-consumer-guide.htm
6. http://www.profilecanada.com/companydetail.cfm?company=179562_Hydraulic_Systems_Limi
ted_St_Johns_NL
7. http://www.westlundpvf.com/locations/atlantic/westlund-newfoundland/
8. http://sedc-coalition.eu/wp-content/uploads/2011/07/CREEDAC-Canadian-Residential-Hot-
Water-Apr-2005.pdf
9. http://www.benjaminmoore.com/en-us/for-architects-and-designers/epoxy-coatings
10. Eslami-nejad, P., & Bernier, M. (2009). Impact of Greywater Heat
Recovery on the Electrical Demand of Domestic Hot Water Heaters.
11. Natural Resources Canada. (2005). R-2000 Standard.
12. Health Canada. (2010). Canadian Guidelines for Domestic Reclaimed Water for Use in Toilet and
Urinal Flushing.
13. See Line Group Inc. (2005). Technology Assessment Study and TRC Analysis.
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APPENDIX A- Project Schedule
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APPENDIX B – Technical Drawing Packages
- Final Drawing Package
- Initial Drawing Package
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Initial Drawing Package
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APPENDIX C – Theoretical Calculations
Appendix C1: Predicted Values Calculations Explanation
The iterative method to vary T∞, the grey water temperature acting at the surface of the coil is
described below:
- 1. From initial temperatures and volumes of water associated with the constructed model,
the energy of the potable water in the coil and the grey water in the reservoir is calculated.
Eold = Mass*Told*cp
- 2. A time-step for iterations is selected corresponding to the transit time of the coil.
Time Step = (Mass in coil) / (mass flow rate through coil)
- 3. The grey water average temperature is modified to account for the grey water coming in
from the shower and the grey water leaving at the overspill per time-step. These
temperatures are different, and if the grey water average temperature changes to reflect
this.
Eold,GW after flow = Eold GW + [(Mass in)*TGW in *cp] – [(Mass out) *Told*cp]
TGW after flow = T∞ = (Eold,GW after flow)/(MassGW * cp)
- 4. The temperature rise of a slug of potable water is calculated according to the following
equation:
(Incropera, p.472)
- 5. The energy of the slug of potable water leaving the device is subtracted from the energy
of the grey water.
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EPotable slug = (MassPotable slug) * cp*( Tm,o- Tm,i)
EGW after potflow = Eold,GW after flow - EPotable slug
- 6. The energy lost to the environment through the reservoir side walls per time-step is
subtracted from the grey water.
qloss = (TGW after potflow) – External Environment)/Req2
Eloss to envirnoment = qloss * (timestep)
EGW after loss = EGW after potflow – Eloss to envirnoment
- 7. The new grey water temperature is reinitialized for the next time-step and return to step
1.
Appendix C2: Estimated Convection Coefficient for Potable Coil
For out constructed model,
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K = 0.59
volflow = 0.000095
m dot = 0.095
Pr = 6.62
Di = 0.01905
Cm = 0.0762
mew = 0.001225
mew surface
temp = 0.0013
Red = 5183.256
Red dc = 2591.628
a = 1.000021
b = 1.072054
Nud = 52.68715
hi = 1631.781
Appendix C3: Comparison of Theoretical and Experimental Results
The experimental data is presented in Appendix E while the predicted values calculation
procedure is presented in C3. Through comparing both data, the following correction to the initial values
of the convection coefficients was observed to provide a better fit:
The theoretical and experimental values are shown in (APP?). Using the results of the model
tests, convection coefficients were varied from the initial estimates to better fit the data by trial and
error. The initial estimates and revised combinations of heat transfer coefficients which yield a better fit
to the data in are stated below:
Original:
‘hpot’ = 1631 (W / m2·K)
‘hgrey,flow’ = 1000 (W/ m2·K)
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‘hgrey,idle’ = 75 (W / m2·K)
Revised:
‘hpot’ = 1631 (W / m2·K)
‘hgrey,flow’ = between 800 and 1500 (W/ m2·K)
‘hgrey,idle’ = Between 20-100 (W / m2·K)
These new values were chosen due to better fitting the data by trial and error across all
experiments. These new values are used in the theoretical model and plotted against the experimental
data in figures C1 through C10.
Theoretical & Experimental - Potable & Greywater Temperatures
Both Flowing @ 1.4 gpm
0
5
10
15
20
25
30
35
40
45
50
0 200 400 600 800 1000 1200
Time (s)
Tem
pera
ture
s (°C
)
Greywater In Greywater OutPotable Water In Potable Water OutGreywater In Experimental Experimental Grey Water OutPotable Water In Experimental Experimental Potable Water Out
Figure C1: Three 10 minute “Showers” in 40 Minutes, Shower Flow at 1.4gpm.
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Theoretical & Experimental - Potable & Greywater Temperatures -
Both Flowing Both Flowing @ 1.4 gpm
0
5
10
15
20
25
30
35
40
45
50
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Time (s)
Tem
pera
ture
s (°C
)
Theoretical Greywater In Theoretical Greywater OutTheoretical Potable Water In Theoretical Potable Water OutExperimental Greywater In Experimental Grey Water OutExperimental Potable Water In Experimental Potable Water Out
Figure C2: Three Showers in 40 Minutes, Shower Flow at 1.6gpm.
Theoretical & Experimental - Potable & Greywater Temperatures
Both Flowing @ 2.0 gpm
0
5
10
15
20
25
30
35
40
45
0 200 400 600 800 1000 1200
Time (s)
Tem
pera
ture
s (°C
)
Greywater In Greywater OutPotable Water In Potable Water OutGreywater In Experimental Experimental Grey Water OutPotable Water In Experimental Experimental Potable Water Out
Figure C3: Three Showers in 40 Minutes, Shower Flow at 2.0gpm.
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Theoretical & Experimental - Potable & Greywater Temperatures
Both Flowing @ 2.5 gpm
0
5
10
15
20
25
30
35
40
45
0 200 400 600 800 1000 1200
Time (s)
Tem
pera
ture
s (°C
)
Greywater In Greywater OutPotable Water In Potable Water OutGreywater In Experimental Experimental Grey Water OutPotable Water In Experimental Experimental Potable Water Out
Figure C4: Three 10 minute ‘Showers’ in 40 Minutes, Shower Flow at 2.5gpm.
Theoretical & Experimental Potable (Flowing @ 1.5gpm)
& Greywater (Idle) Temperatures
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Time (s)
Tem
pera
ture
(°C
)
Potable Water In Potable Water Out Greywater
Experimental Potable Water In Experimental Potable Water Out Experimental Greywater
Figure C5: Potable Flow Only, Potable flow at 1.5gpm, grey water initially at 26°C.
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Theoretical & Experimental Potable (Flowing @ 1.5gpm) & Greywater
(Idle) Temperatures
0
5
10
15
20
25
30
35
40
45
0 100 200 300 400 500 600
Time (s)
Tem
pera
ture
(°C
)
Potable Water In Potable Water Out Greywater
Experimental Potable Water In Experimental Potable Water Out Experimental Greywater
Figure C6: Potable Flow Only, Potable flow at 1.5gpm, grey water initially at 38°C
Multi-Stage (1) - Theoretical & Experimental Potable (Flowing @ 0.75gpm) &
Greywater (Flowing @ 1.5gpm) Temperatures
0
10
20
30
40
50
0 100 200 300 400 500 600
Time (s)
Tem
pera
ture
s (°C
)
Greywater In Greywater OutPotable Water In Potable Water OutGreywater In Experimental Experimental Grey Water OutPotable Water In Experimental Experimental Potable Water Out
Figure C7: Multi Stage Part 1
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Multi-Stage (2) - Theoretical & Experimental Potable (Flowing @ 0.75gpm) &
Greywater (Flowing @ 1.5gpm) Temperatures
0
5
10
15
20
25
30
35
0 100 200 300 400 500 600
Time (s)
Tem
pera
ture
s (°C
)
Greywater In Greywater OutPotable Water In Potable Water OutGreywater In Experimental Experimental Grey Water OutPotable Water In Experimental Experimental Potable Water Out
Figure C8: Multi Stage Part 2
Reduced Grey Water Volume
Theoretical & Experimental - Potable & Greywater Temperatures - Both Flowing
0
5
10
15
20
25
30
35
40
45
0 100 200 300 400 500 600
Time (s)
Tem
pera
ture
s (°C
)
Greywater In Greywater OutPotable Water In Potable Water OutGreywater In Experimental Experimental Grey Water OutPotable Water In Experimental Experimental Potable Water Out
Figure C9: Reduced Volume Test
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Continuous Flow - Theoretical & Experimental Potable & Greywater Temperatures
Both Flowing @ 2.5gpm
0
5
10
15
20
25
30
35
40
45
0 200 400 600 800 1000 1200
Time (s)
Tem
pera
ture
s (°C
)
Greywater In Greywater OutPotable Water In Potable Water OutGreywater In Experimental Experimental Grey Water OutPotable Water In Experimental Experimental Potable Water Out
Figure C10: Continuous Flow Test
These adjusted heat transfer coefficient seem to be a better fit of the data than the initial
values. The mass flow was fluctuating during some of these tests in both the simultaneous and potable
only flow cases. The inlet temperatures were seen to be fluctuating in the model test. Also, the sensors
used for the grey water test may have been influenced by their proximity to the coil as this variable was
not noted well during experimentation. These inconsistencies with the model cause scatter and
potentially bias in the data. The theoretical model seems relatively centered in the data across most
tests despite the scatter and bias.
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APPENDIX D – Design of Experiments
Design of Experiments
The model and prototyping stage will involve the construction and testing of a proof-of-
concept device to verify actual performance characteristics. The testing phase will be
completed by running the device under different realistic flow scenarios and using the
information to verify our theoretical and optimization models. The temperatures of the flows
will be measured during regular time intervals and the results will be used to perform an
analysis.
Testing Preparation
In preparation of completing the testing phase of our project we had to establish a
construction and testing location, which we’ve discussed with Craig Mitchell in the thermal lab.
We will be using a location near the back of the room by the doors to the fluids lab so that we
have access to the hot and cold water taps. We will acquire the necessary components for
testing and these will be accessible in time for testing.
Location:
- Thermal/Fluids Laboratory in the Engineering Building at Memorial University of
Newfoundland
Purpose:
- Testing a wastewater heat recovery device in operation under different flow scenarios
to measure the heat transfer
Materials:
- 4 Thermocouples wires
- 2 Digital temperature reader
- Hot and cold water taps
- Hot and cold water hoses
Procedure:
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2. Measure the temperature of the hot and cold water feeds to determine if they match
our predefined values:
a. Hot water -> 37 - 42⁰C (If this temperature is not at the value required, we will
either cool or heat the water until it reaches the desired value)
b. Cold water -> Vary between 3⁰C (Winter) and 10⁰C (Summer)
3. Measure the amount of water for a typical shower, bath and dishwashing load and
devise a method for storing that amount of water at the right temperature
4. Measure the flow rate of the hot and cold water feeds. This will be done by measuring
the time it takes for a tap to fill a container to a certain volume. Flow meters would be
ideal for more accurate measurements, but these would be difficult to install and
calibrate given the small size of our project.
a. If the flow rates match that required for the testing parameters, simply use
these. If not, devise a method for accurate flows using a storage reservoir and
connected hose
5. Connect the device to the hot and cold water feeds and connect the thermocouples in
the appropriate locations. This will be in the incoming and outgoing feeds for both
potable water and greywater. These locations will be determined after model
construction is complete and will be based on the optimal temperature location of the
feeds.
6. The tests will involve testing different flow conditions that would typically be seen in a
residential home such as:
a. Potable water and greywater flowing (Shower and Dishwasher)
i. Testing Type 1 – Three 10 minute showers with 5 minute breaks
1. Q = 1.5, 2, 2.5 gal/min
ii. Testing Type 2 – Continuous running for 20 minutes for Q = 2.5 gal/min
iii. Testing Type 5 – Decrease reservoir volume
iv. Testing Type 6 – Install baffles in tank
b. Potable water flow only (Sink use)
i. Testing Type 3 – Q = 1.5 gal/min
1. Reservoir temp at room temp and 40 ⁰C
c. Multi-stage flow (modular design)
i. Testing Type 4 – Two passes in parallel
1. Flow rates in half, reservoir temp of 2nd test to be greywater out
7. The transient aspect will be measured in small time intervals but will increase when the
system begins to stabilize at steady state.
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8. We will only have access to one digital temperature reader, so we will connect
thermocouple wires in the appropriate locations and connect the temperature reader to
each one every 15 seconds or so.
a. (Note: if this time period is not sufficient to switch over the wires, we will devise
a plan to fix this.)
9. The amount of water for each type of test will be dependent on the input condition
being modelled:
a. Shower – 56 lt
b. Bath – 80 lt
c. Dishwasher load – 25 lt
10. The results will be recorded during the tests and inputted into a spreadsheet so that
numerical analysis can be performed on the results to calculate the amount of heat
transfer.
Results
The results will be recorded on the spreadsheet attached and input into excel.
Analysis
Once the temperatures have been recorded during multiple tests, we will use these to
perform an analysis on the results. With the results of our different flow scenarios we can
develop models for typical household energy savings possible depending on the hot water use.
By comparing the results using different flow rates, the use of efficient fixtures can be analyzed.
We will also examine the multi-stage design and it’s effectiveness. This will involve calculating
the coil or simultaneous heat transfer through the first section of our module and calculating
the reservoir or batch heat transfer through the second section of our module. By verifying
both of these heat transfer amounts, we can compare to the theoretical values that we
generated using our calculation spreadsheet. Verification of the cost savings associated with
our device will also be completed in comparison to our initial cost calculations.
Along with our theoretical and optimization calculations, we can use the results of our
tests to determine final sizes and arrangements. By comparing the results of actual and
theoretical we can determine the accuracy of our assumptions used in the theoretical
calculations and determine some methods for improvements. We will also be able to determine
the most feasible arrangement of our modules based on the amount of heat transfer measured
in each test.
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APPENDIX E – Testing Results
Test 3 – Q = 1.4 gal/min
Date: March 30th, 2012
Experiment #: 3
Location:
Fluids
Lab
Module Tested: Coil
Potable Flow: 1.4 gal/min
Greywater Flow: 1.4 gal/min
Initially: Reservoir temperature at 28 ⁰C
Simulating three 10 minute showers with two 5 minute breaks
- Breaks are every 10 minutes"
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water
Out
Greywater
In
Greywater
Out ΔT pot ΔT grey
0 9.1 18 44.7 28.3 8.9 16.4
30 7.2 16 38.2 28.8 8.8 9.4
60 7 15.7 38.2 28.7 8.7 9.5
90 6.9 15.7 38.5 28.8 8.8 9.7
120 6.8 15.6 38.8 28.3 8.8 10.5
150 6.8 15.7 38.8 28.9 8.9 9.9
180 6.7 15.9 38.7 28.9 9.2 9.8
210 6.6 15.8 38.6 29 9.2 9.6
240 6.6 15.8 38.7 29 9.2 9.7
270 6.5 15.8 38.6 29 9.3 9.6
300 6.5 15.8 38.6 28.9 9.3 9.7
330 6.5 15.8 38.6 29 9.3 9.6
360 6.4 16 38.6 29.1 9.6 9.5
390 6.3 15.9 38.6 29.1 9.6 9.5
420 6.3 15.7 39.1 29.1 9.4 10
450 6.2 15.8 38.8 29 9.6 9.8
480 6.1 16 38.7 29.1 9.9 9.6
510 6.1 15.7 38.9 29.1 9.6 9.8
540 6.1 15.8 38.8 29.2 9.7 9.6
570 6 15.8 38.8 29.2 9.8 9.6
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10 MIN 5.9 15.8 39 29 9.9 10
630 5.9 15.8 39 29.2 9.9 9.8
660 5.8 15.7 39.1 29.1 9.9 10
690 5.7 15.8 39 29.1 10.1 9.9
720 5.7 15.8 39 29.2 10.1 9.8
750 5.6 15.5 39.1 29.2 9.9 9.9
780 5.6 15.8 39 29.2 10.2 9.8
810 5.6 15.6 39 29.2 10 9.8
840 5.5 15.8 39 29.2 10.3 9.8
870 5.5 15.8 39 29.2 10.3 9.8
900 5.5 15.6 39.1 29.2 10.1 9.9
930 5.5 15.6 39 29.1 10.1 9.9
960 5.5 15.8 39 29.1 10.3 9.9
990 5.6 15.7 39 29.3 10.1 9.7
1020 5.6 15.7 39 29.2 10.1 9.8
1050 5.6 15.6 39.1 29.2 10 9.9
1080 5.5 15.7 39 29.1 10.2 9.9
1110 5.5 15.7 39.1 29.1 10.2 10
1140 5.5 15.6 39.4 29.1 10.1 10.3
1170 5.5 15.7 39.1 29.1 10.2 10
20 MIN 5.5 15.7 39 29 10.2 10
1230 5.4 15.5 39 29.2 10.1 9.8
1260 5.4 15.6 39 29 10.2 10
1290 5.4 15.7 39 29.1 10.3 9.9
1320 5.4 15.5 39 29 10.1 10
1350 5.3 15.5 38.9 29.1 10.2 9.8
1380 5.3 15.6 38.9 29.1 10.3 9.8
1410 5.3 15.6 39 29 10.3 10
1440 5.3 15.5 38.8 29.1 10.2 9.7
1470 5.3 15.5 38.9 29.1 10.2 9.8
1500 5.3 15.4 38.9 29.1 10.1 9.8
1530 5.3 15.4 38.9 29.1 10.1 9.8
1560 5.3 15.5 39 29.1 10.2 9.9
1590 5.3 15.4 38.9 29.1 10.1 9.8
1620 5.3 15.5 38.9 29 10.2 9.9
1650 5.3 15.5 38.9 29.1 10.2 9.8
1680 5.4 15.4 39 29.1 10 9.9
1710 5.4 15.5 39 29 10.1 10
1740 5.4 15.6 39 29.1 10.2 9.9
1770 5.4 15.4 39 29.1 10 9.9
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30 MIN 5.4 15.4 38.9 29.1 10 9.8
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
5.86 15.71 38.99 29.05 9.85 9.93
Potable Water Inlet/Outlet Temps
Greywater Inlet/Outlet Temps
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Model Testing Results
Date: March 30th, 2012
Experiment #: 5
Location:
Fluids
Lab
Module Tested: Coil
Potable Flow: 1.6 gal/min
Greywater Flow: 1.6 gal/min
Initially: Reservoir temperature at 24.5 ⁰C
Simulated three 10 minute showers with two 5 minute breaks
- Breaks are every 10 minutes
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water Out
Greywater
In
Greywater
Out ΔT pot Δ grey
0 13 20.9 36.4 24.5 7.9 11.9
30 10.7 16.5 32.9 24.3 5.8 8.6
60 10.2 16.4 32.9 24.5 6.2 8.4
90 10.2 16.8 41.8 25.4 6.6 16.4
120 10 17.1 36.2 26 7.1 10.2
150 9.7 16.6 35.4 26 6.9 9.4
180 9.7 16.3 41.8 26.7 6.6 15.1
210 9.5 16.8 42.5 26.9 7.3 5.6
240 9.4 16.8 43.3 27.2 7.4 16.1
270 9.3 17.1 44 27.6 7.8 16.4
300 9.3 16.9 44.9 28 7.6 16.9
330 9.2 16.8 45.3 28 7.6 17.3
360 9.1 17 45.5 28.2 7.9 17.3
390 9 16.9 35.6 28.9 7.9 6.7
420 8.9 16.6 40.5 28.5 7.7 12
450 8.8 16.9 38.6 28.1 8.1 10.5
480 8.7 16.8 39.3 28.4 8.1 10.9
510 8.7 16.6 40.2 28.4 7.9 11.8
540 8.6 16.7 40.8 28.4 8.1 12.4
570 8.5 16.9 41.7 28.6 8.4 13.1
10 MIN 8.4 16.9 42.2 28.7 8.5 13.5
630 5.8 14.5 40.2 28.6 8.7 11.6
Team Flüggen – Final Report
73
660 5.4 14.9 41.1 28.4 9.5 12.7
690 5.3 14.8 41.1 28.2 9.5 12.9
720 5.3 14.6 41.3 28.2 9.3 13.1
750 5.2 14.8 41.2 28.1 9.6 13.1
780 5.1 14.6 41.3 28.1 9.5 13.2
810 5.1 14.8 37.5 28.4 9.7 9.1
840 5 14.7 37.8 28.3 9.7 9.5
870 5 14.6 37.8 28.2 9.6 9.6
900 5 14.6 37.6 28.2 9.6 9.4
930 5 14.3 37.7 28.1 9.3 9.6
960 4.9 14.6 37.7 28.1 9.7 9.6
990 4.9 14.5 37.9 28 9.6 9.9
1020 4.9 14.4 37.7 28.1 9.5 9.6
1050 4.9 14.5 37.8 28 9.6 9.8
1080 4.9 14.2 37.7 27.9 9.3 9.8
1110 4.9 14.5 37.8 27.9 9.6 9.9
1140 4.9 14.4 37.7 27.9 9.5 9.8
1170 4.9 14.4 37.8 27.9 9.5 9.9
20 MIN 4.9 14.4 37.7 27.9 9.5 9.8
1230 4.9 14.6 36.9 27.5 9.7 9.4
1260 4.9 14.5 37.2 27.4 9.6 9.8
1290 4.9 14.3 37.3 27.3 9.4 10
1320 4.8 14.5 37.4 27.4 9.7 10
1350 4.8 14.4 37.4 27.5 9.6 9.9
1380 4.8 14.2 37.5 27.5 9.4 10
1410 4.8 14.2 37.6 27.5 9.4 10.1
1440 4.8 14.2 37.4 27.5 9.4 9.9
1470 4.8 14.3 37.4 27.5 9.5 9.9
1500 4.8 14.4 37.4 27.5 9.6 9.9
1530 4.8 14.4 37.4 27.4 9.6 10
1560 4.8 14.1 37.2 27.5 9.3 9.7
1590 4.8 14.1 37.3 27.5 9.3 9.8
1620 4.8 14.1 37.3 27.4 9.3 9.9
1650 4.8 14.2 37.4 27.4 9.4 10
1680 4.8 14.1 37.3 27.4 9.3 9.9
1710 4.8 14.2 37.3 27.3 9.4 10
1740 4.8 14 37.3 27.3 9.2 10
1770 4.8 14.2 37.3 27.4 9.4 9.9
30 MIN 4.7 14.3 37.2 27.4 9.6 9.8
Team Flüggen – Final Report
74
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
6.50 15.29 8.73 27.58 8.79 11.15
Potable Water Inlet/Outlet Temps
Greywater Inlet/Outlet Temps
Team Flüggen – Final Report
75
Model Testing Results
Date: March 30th, 2012
Experiment #: 7
Location:
Fluids
Lab
Module Tested: Coil
Potable Flow: 2 gal/min
Greywater Flow: 2 gal/min
Initially: Reservoir temperature at 25.6 ⁰C
Simulating three 10 minute showers with two 5 minute breaks
- Breaks are every 10 minutes
Test Results:
Temperatures (⁰C)
Time (s)
Potabl
Water In
Potable
Water Out
Greywater
In
Greywater
Out ΔT pot ΔT grey
0 5.5 16.5 38.6 25.6 11 13
30 5.2 11 39.6 23.7 5.8 15.9
60 5.2 11.4 40.2 23.2 6.2 17
90 5.1 11.5 40.7 21.5 6.4 19.2
120 5.1 11.8 41 22.1 6.7 18.9
150 5.1 12 41 22.4 6.9 18.6
180 .1 12.5 41.5 23.4 7.4 18.1
210 5.1 12.8 42.2 23.8 7.7 18.4
240 5.1 13.2 39.7 24.8 8.1 14.9
270 5 13 40.5 24.9 8 15.6
300 5 13.3 40.8 25.8 8.3 15
330 5 13.7 41.3 26.4 8.7 14.9
360 5 13.8 41.9 26.8 8.8 15.1
390 4.9 14.3 42.4 27.6 9.4 14.8
420 4.9 14.2 42.5 28 9.3 14.5
450 4.8 14.2 42.6 28.6 9.4 14
480 4.8 13.2 42.6 29 8.4 13.6
510 4.5 13.3 42.6 29.2 8.8 13.4
540 4.5 13.3 42.6 29.3 8.8 13.3
570 4.7 13.5 42.6 29.3 8.8 13.3
10 MIN 4.7 13.4 42.6 29.5 8.7 13.1
630 4.8 13.2 38.8 29.5 8.4 9.3
Team Flüggen – Final Report
76
660 4.8 13.2 39.8 29.1 8.4 10.7
690 4.7 13.3 39.8 29.3 8.6 10.5
720 4.7 13.3 39.9 29.4 8.6 10.5
750 4.7 13.4 39.9 29.5 8.7 10.4
780 4.7 13.4 40 29.6 8.7 10.4
810 4.7 13.3 39.9 29.7 8.6 10.2
840 4.6 13.3 39.9 29.7 8.7 10.2
870 4.6 13.4 39.8 29.8 8.8 10
900 4.6 13.5 39.9 29.8 8.9 10.1
930 4.6 13.5 39.9 29.9 8.9 10
960 4.6 13.5 39.9 29.9 8.9 10
990 4.6 13.6 39.8 29.8 9 10
1020 4.6 13.6 39.8 30 9 9.8
1050 4.6 13.5 39.8 30 8.9 9.8
1080 4.6 13.6 39.7 29.9 9 9.8
1110 4.6 13.5 39.7 30 8.9 9.7
1140 4.6 13.6 39.7 30.1 9 9.6
1170 4.6 13.5 39.6 30.2 8.9 9.4
20 MIN 4.6 13.5 39.6 30.2 8.9 9.4
1230 4.9 13.4 38.5 30 8.5 8.5
1260 4.7 13.3 39.1 28.4 8.6 10.7
1290 4.7 13.1 39.3 29.8 8.4 9.5
1320 4.7 13.1 39.4 25.9 8.4 13.5
1350 4.7 13 39.4 25.5 8.3 13.9
1380 4.7 13.2 39.3 29.9 8.5 9.4
1410 4.7 13 39.2 29.9 8.3 9.3
1440 4.7 12.6 39.3 29.8 7.9 9.5
1470 4.7 12.6 39.4 29.8 7.9 9.6
1500 4.7 13.4 39.3 29.8 8.7 9.5
1530 4.8 13.3 39.3 29.9 8.5 9.4
1560 4.8 13.4 39.3 29.8 8.6 9.5
1590 4.8 13.5 39.3 29.9 8.7 9.4
1620 4.8 13.4 39.2 29.9 8.6 9.3
1650 4.8 13.4 39.2 29.9 8.6 9.3
1680 4.8 13.5 39.2 29.9 8.7 9.3
1710 4.8 13.5 39.2 29.9 8.7 9.3
1740 4.8 13.4 39.2 29.9 8.6 9.3
1770 4.8 13.5 39.3 29.9 8.7 9.4
30 MIN 4.8 13.6 39.3 29.9 8.8 9.4
Team Flüggen – Final Report
77
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
4.79 13.28 40.15 28.33 8.48 11.83
Potable Water Inlet/Outlet Temps
Greywater Inlet/Outlet Temps
Team Flüggen – Final Report
78
Model Testing Results
Date: April 2th, 2012
Experiment #: 8
Location:
Fluids
Lab
Module Tested: Coil
Potable Flow: 2.5 gal/min
Greywater Flow: 2.5 gal/min
Initially: Reservoir temperature at 17
Simulating three 10 minute showers with two 5 minute breaks
- Breaks are every 10 minutes
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water Out
Greywater
In
Greywater
Out ΔT pot ΔT grey
0 6.7 8.9 35.4 17.2 2.2 18.2
30 6.6 9.6 37.5 17.2 3 20.3
60 6.5 10.8 37.8 20.6 4.3 17.2
90 6.4 11 38 19.9 4.6 18.1
120 6.4 11.4 38.2 21.3 5 16.9
150 6.4 11.6 38.2 22.2 5.2 16
180 6.5 11.9 38.1 23.2 5.4 14.9
210 6.5 12.2 38.2 23.9 5.7 14.3
240 6.3 12.3 38.2 25.2 6 13
270 6.2 12.4 38.1 25.1 6.2 13
300 5.9 12.5 38 25.7 6.6 12.3
330 5.7 12.3 37.9 26.5 6.6 11.4
360 5.3 12.2 37.8 26.8 6.9 11
390 5.3 12.3 37.8 27 7 10.8
420 5.2 12.4 37.8 27.4 7.2 10.4
450 5.1 12.2 37.8 27.5 7.1 10.3
480 5 12.2 37.7 28.1 7.2 9.6
510 4.9 12.2 37.5 28 7.3 9.5
540 4.9 12.1 37.8 28.1 7.2 9.7
570 4.8 12.2 37.7 28.2 7.4 9.5
10 MIN 4.9 12.3 38.3 28.4 7.4 9.9
630 5 12.2 37.2 28.3 7.2 8.9
Team Flüggen – Final Report
79
660 4.8 12 38 28.3 7.2 9.7
690 4.7 12 38 28.2 7.3 9.8
720 4.7 12.2 38 28.5 7.5 9.5
750 4.7 12.1 38.1 29 7.4 9.1
780 4.7 12.1 38.1 29 7.4 9.1
810 4.7 12.3 38.1 28.9 7.6 9.2
840 4.7 12.4 38.1 29 7.7 9.1
870 4.7 12.3 38.2 29.5 7.6 8.7
900 4.8 12.3 38.2 29.5 7.5 8.7
930 4.7 12.3 38.2 29.3 7.6 8.9
960 4.7 12.2 38.2 29.4 7.5 8.8
990 4.7 12.3 38.2 29.4 7.6 8.8
1020 4.7 12.5 38.2 29.9 7.8 8.3
1050 4.7 12.5 38.2 29.8 7.8 8.4
1080 4.7 12.3 38.2 29.8 7.6 8.4
1110 4.7 12.4 38.2 29.9 7.7 8.3
1140 4.7 12.7 38.2 29.7 8 8.5
1170 4.7 12.3 38.3 30.3 7.6 8
20 MIN 4.8 12.6 38.2 29.9 7.8 8.3
1230 5.2 13.2 37.8 29.7 8 8.1
1260 5 13 38.3 29.6 8 8.7
1290 5 12.8 38.4 29.4 7.8 9
1320 4.9 13 38.5 29.9 8.1 8.6
1350 4.9 13.1 38.5 30.2 8.2 8.3
1380 4.8 12.9 38.4 29.9 8.1 8.5
1410 4.8 12.8 38.5 29.9 8 8.6
1440 4.8 13 38.5 30.1 8.2 8.4
1470 4.8 13.2 38.5 30.2 8.4 8.3
1500 4.8 13 38.8 30.2 8.2 8.6
1530 4.7 12.9 38.4 30.4 8.2 8
1560 4.8 13 38.6 30.3 8.2 8.3
1590 4.7 13.1 38.4 30.3 8.4 8.1
1620 4.7 13 38.5 30.3 8.3 8.2
1650 4.7 13.2 38.5 30.5 8.5 8
1680 4.7 12.8 38.4 30.3 8.1 8.1
1710 4.7 13 38.4 30.4 8.3 8
1740 4.7 12.9 38.5 30.5 8.2 8
1770 4.7 13 38.5 30.5 8.3 8
30 MIN 4.7 13.3 38.5 30.6 8.6 7.9
Team Flüggen – Final Report
80
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
5.12 12.35 38.11 27.97 7.23 10.14
Potable Water Inlet/Outlet Temps
Greywater Inlet/Outlet Temps
Team Flüggen – Final Report
81
Model Testing Results
Date: March 30th, 2012
Experiment #: 4
Location:
Fluids
Lab
Module Tested: Coil
Potable Flow: 2.516 gal/min
Greywater Flow: 2.4 gal/min
Initially: Reservoir temperature at 25.7 ⁰C
Simulating continuous running with an input greywater of 38 ⁰C
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water Out
Greywater
In
Greywater
Out ΔT pot ΔT grey
0 6.6 12.2 31.9 25.7 5.6 6.2
30 6.4 12.2 31.9 25.8 5.8 6.1
60 6.3 12.1 31.9 25.9 5.8 6
90 6.2 12 32.1 26 5.8 6.1
120 6.2 12 32.1 26 5.8 6.1
150 6 11.9 35.6 26 5.9 9.6
180 6 12.2 36.4 26.5 6.2 9.9
210 6 12.4 39.3 26.8 6.4 12.5
240 6 12.8 39.6 27.6 6.8 12
270 5.9 12.8 39.8 27.9 6.9 11.9
300 5.8 12.9 40 28.5 7.1 11.5
330 5.6 13 40.5 28.9 7.4 11.6
360 5.5 13 40.8 29.2 7.5 11.6
390 5.5 13.5 40.9 29.7 8 11.2
420 5.4 13.8 41 29.9 8.4 11.1
450 5.3 12.6 41 30 7.3 11
480 5.2 12.6 38.5 30.7 7.4 7.8
510 5.2 12.7 38.4 30.5 7.5 7.9
540 5.2 12.5 38.3 30.3 7.3 8
570 5.2 12.5 38.4 30.3 7.3 8.1
10 MIN 5.2 12.4 38.2 30.4 7.2 7.8
630 5.1 12.6 38.3 30.3 7.5 8
Team Flüggen – Final Report
82
660 5.1 12.5 38.3 30.3 7.4 8
690 5.1 12.6 38.3 30.4 7.5 7.9
720 5.1 12.5 38.3 30.3 7.4 8
750 5.1 12.5 38.3 30.3 7.4 8
780 5.1 12.6 38.3 30.3 7.5 8
810 5.1 12.6 38.2 30.5 7.5 7.7
840 5.1 12.7 38.3 30.5 7.6 7.8
870 5.1 12.6 38.2 30.2 7.5 8
900 5.1 12.6 38.2 30.2 7.5 8
930 5 12.5 38.2 30.3 7.5 7.9
960 4.9 12.5 38.1 30.2 7.6 7.9
990 4.8 12.4 38.1 30.2 7.6 7.9
1020 4.8 12.3 38.1 30.1 7.5 8
1050 4.6 12.2 38 30.1 7.6 7.9
1080 4.6 12.2 38 29.9 7.6 8.1
1110 4.5 12.2 37.9 30.1 7.7 7.8
1140 4.5 12.2 38 30.1 7.7 7.9
1170 4.4 12.1 37.9 30.1 7.7 7.8
20 MIN 4.4 12 37.9 30.1 7.6 7.8
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
5.32 12.50 37.79 29.20 7.18 8.60
Potable Water Inlet/Outlet Temps
Team Flüggen – Final Report
83
Greywater Inlet/Outlet Temps
Team Flüggen – Final Report
84
Team Fluggen
Model Testing Results
Date: April 2nd, 2012
Experiment #: 11
Location:
Fluids
Lab
Module Tested: Coil
Potable Flow: 1.5 gal/min
Greywater
Flow: 1.5 gal/min
Initially: Reservoir temperature at 24 ⁰C
Reduced volume in reservoir, 11 lt less
Note: flow rates had to be adjusted a few times during this test
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water
Out
Greywater
In Greywater Out ΔT pot ΔT grey
0 7.1 18.9 34 24 11.8 10
30 7.2 15.3 37.9 24.7 8.1 13.2
60 7 15.7 38.3 24.9 8.7 13.4
90 7 15.8 38.4 25 8.8 13.4
120 7 15.8 38.6 25.4 8.8 13.2
150 7 15.6 33.8 26.1 8.6 7.7
180 7 15.5 35.3 25.9 8.5 9.4
210 6.9 15.4 35.3 25.9 8.5 9.4
240 6.9 15.3 36.4 25.9 8.4 10.5
270 6.9 15.4 36.9 26.1 8.5 10.8
300 6.9 15.4 36.8 26 8.5 10.8
330 6.9 15.4 36.7 26.1 8.5 10.6
360 6.9 15.4 36.7 26.1 8.5 10.6
390 6.9 16.4 36.6 26.1 9.5 10.5
420 6.8 16.7 36.5 26.2 9.9 10.3
450 6.7 16.5 36.2 26.3 9.8 9.9
480 6.5 14.6 36.2 26.3 8.1 9.9
510 6.4 14.6 36 26 8.2 10
540 6.2 13.9 36 25.5 7.7 10.5
570 6.1 13.9 36 25.4 7.8 10.6
Team Flüggen – Final Report
85
10 MIN 6 13.8 35.8 25 7.8 10.8
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
6.78 15.49 36.40 25.66 8.71 10.74
Potable Water Inlet/Outlet Temps
Greywater Inlet/Outlet Temps
Team Flüggen – Final Report
86
Model Testing Results
Date: April 2nd, 2012
Experiment #: 9
Location:
Fluids
Lab
Module Tested: Coil
Potable Flow: 0.75 gal/min
Greywater Flow: 1.5 gal/min
Initially: Reservoir temperature at 25 ⁰C
Simulating modular operation with two units. Potable flow is in parallel
and therefor split in half.
For second part, use Tout greywater for tank temp
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water
Out
Greywate
r In
Greywater
Out ΔT pot ΔT grey
0 7.1 26.4 35 25 19.3 10
30 5.8 18.3 37 26.1 12.5 10.9
60 5.4 19 37.9 26.7 13.6 11.2
90 5.4 19.2 38.3 27.3 13.8 11
120 5.3 19.5 38.7 27.1 14.2 11.6
150 5.3 19.8 39 27.3 14.5 11.7
180 5.3 20 39.1 27.6 14.7 11.5
210 5.4 20.2 39.2 27.9 14.8 11.3
240 5.4 19.3 39.3 28.3 13.9 11
270 5.4 18.5 39.3 28.5 13.1 10.8
300 5.3 18.4 39.3 28.7 13.1 10.6
330 5.3 19.3 39.3 28.9 14 10.4
360 5.3 19.5 39.3 29.2 14.2 10.1
390 5.3 19.9 39.6 29.2 14.6 10.4
420 5.3 19.8 39.6 29.4 14.5 10.2
450 5.3 20.2 39.7 29.5 14.9 10.2
480 5.4 20.1 39.8 29.9 14.7 9.9
510 5.4 20.1 39.9 29.9 14.7 10
540 5.3 20.3 39.9 30.1 15 9.8
570 5.3 20.5 39.7 30.2 15.2 9.5
10 MIN 5.3 20.4 39.7 30.3 15.1 9.4
Team Flüggen – Final Report
87
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
5.44 19.94 38.98 28.43 14.50 10.55
Potable Water Inlet/Outlet Temps
Greywater Inlet/Outlet Temps
Team Flüggen – Final Report
88
Model Testing Results
Date: April 2nd, 2012
Experiment #: 10
Location:
Fluids
Lab
Module Tested: Coil
Potable Flow: 0.75 gal/min
Greywater Flow: 1.5 gal/min
Initially: Reservoir temperature at greywater outlet of first test (29-30) ⁰C
Simulating modular operation with two units. Potable flow is in parallel
and therefore split in half.
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water Out
Greywater
In
Greywater
Out ΔT pot ΔT grey
0 7.3 25.6 30.2 26.6 18.3 3.6
30 6.6 19.6 30.6 26.5 13 4.1
60 6.5 18.7 30.7 26.5 12.2 4.2
90 6.6 18.3 27.2 25.6 11.7 1.6
120 6.6 18.1 27.3 25.6 11.5 1.7
150 6.6 17.7 29.1 25.6 11.1 3.5
180 6.6 17.9 29.4 25.2 11.3 4.2
210 6.6 17.7 29.5 25.2 11.1 4.3
240 6.6 17.6 29.5 25.2 11 4.3
270 6.6 17.6 29.7 25.2 11 4.5
300 6.6 17.6 29.7 25.2 11 4.5
330 6.6 17.6 29.8 25.2 11 4.6
360 6.5 17.6 29.9 25.2 11.1 4.7
390 6.5 17.5 29.8 25.1 11 4.7
420 6.5 17.3 29.8 25.1 10.8 4.7
450 6.4 17.2 30.1 25.3 10.8 4.8
480 6.9 17.3 29.9 25 10.4 4.9
510 6.3 17.1 29.9 25 10.8 4.9
540 6.3 17.2 29.9 25 10.9 4.9
570 6.2 17 29.9 25 10.8 4.9
10 MIN 6.2 17.2 30.9 24.9 11 6
Team Flüggen – Final Report
89
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
6.55 18.07 29.66 25.39 11.51 4.27
Potable Water Inlet/Outlet Temps
Greywater Inlet/Outlet Temps
Team Flüggen – Final Report
90
Model Testing Results
Date:
March 30th,
2012
Experiment #: 6
Location:
Fluids
Lab
Module
Tested: Coil
Potable Flow: 1.5 gal/min
Greywater
Flow: 0 gal/min
Initially: Reservoir temperature at 25 ⁰C
Simulating batch flow with low potable flow and no greywater flow
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water
Out
Greywater
Tank Greywater Out ΔT pot
ΔT
grey
0 5.5 12.3 26.3 24.2 6.8 -2.1
30 5.5 12.4 25.5 24.1 6.9 -1.4
60 5.5 12.1 24.8 23.9 6.6 -0.9
90 5.4 11.9 24.8 23.8 6.5 -1
120 5.4 11.6 23.9 23.7 6.2 -0.2
150 5.4 11.5 23.6 23.8 6.1 0.2
180 5.4 11.3 22.9 23.6 5.9 0.7
210 5.4 11.1 22.7 23.3 5.7 0.6
240 5.3 11 22.2 23.3 5.7 1.1
270 5.3 10.8 21.9 23.4 5.5 1.5
300 5.3 10.6 21.5 23.2 5.3 1.7
330 5.2 10.3 21.1 23.2 5.1 2.1
360 5.2 10.3 20.9 23.2 5.1 2.3
390 5.2 10.1 20.6 23.2 4.9 2.6
420 5.1 10 20.3 23.3 4.9 3
450 5.1 9.8 19.9 23.2 4.7 3.3
480 5 9.7 19.7 23.1 4.7 3.4
510 5 9.5 19.5 23 4.5 3.5
540 4.9 9.4 19 23.2 4.5 4.2
570 4.9 9.2 18.9 23.2 4.3 4.3
Team Flüggen – Final Report
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10 MIN 4.9 9.1 18.7 23.1 4.2 4.4
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp
Avg
ΔTg
Avg
5.23 10.67 23.43 21.84 5.43 1.59
Potable Water Inlet/Outlet Temps
Greywater Inlet/Outlet Temps
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Model Testing Results
Date: April 2nd, 2012
Experiment #: 12
Location:
Fluids
Lab
Module
Tested: Coil
Potable Flow: 1.5 gal/min
Greywater
Flow: 0 gal/min
Initially: Reservoir temperature at 37 ⁰C
Simulating batch flow with low potable flow and no greywater flow
Test Results:
Temperatures (⁰C)
Time (s)
Potable
Water In
Potable
Water
Out
Greywate
r Tank Greywater Out ΔT pot ΔT grey
0 7.5 22 36.2 37.5 14.5 -1.3
30 7.5 20.7 36 37.6 13.2 -1.6
60 7.5 22 35.6 40 14.5 -4.4
90 7.5 20.4 35.7 40.6 12.9 -4.9
120 7.6 20.2 34.8 40.3 12.6 -5.5
150 7.6 19 34.6 40.2 11.4 -5.6
180 7.6 19.6 33.9 39.9 12 -6
210 7.7 18.9 33.2 39.9 11.2 -6.7
240 7.7 18.9 33.1 39.8 11.2 -6.7
270 7.6 18.3 32.3 39.7 10.7 -7.4
300 7.6 18.1 31.8 39.5 10.5 -7.7
330 7.6 17.9 31.5 39.5 10.3 -8
360 7.5 17.7 31.1 39.5 10.2 -8.4
390 7.5 17.2 30.5 39.3 9.7 -8.8
420 7.4 16.9 30 39.2 9.5 -9.2
450 7.3 16.6 29.4 39 9.3 -9.6
480 7.2 16.3 28.9 39 9.1 -10.1
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510 7.1 16 28.5 39 8.9 -10.5
540 7 15.8 28 38.9 8.8 -10.9
570 6.9 15.3 27.5 38.9 8.4 -11.4
10 MIN 6.8 15 27 38.7 8.2 -11.7
630 6.7 14.6 26.4 38.5 7.9 -12.1
660 6.6 14.5 26 38.41 7.9 -12.41
690 6.5 14.1 25.4 38.4 7.6 -13
720 6.5 13.9 25.2 38.3 7.4 -13.1
750 6.9 13.7 24.8 38.3 6.8 -13.5
780 6.3 13.5 24.5 38.2 7.2 -13.7
810 6.2 13.2 24 38.1 7 -14.1
840 6.2 13.1 23.8 38 6.9 -14.2
870 6.2 12.9 23.5 38 6.7 -14.5
Tci Avg Tco Avg Thi Avg Tho Avg ΔTp Avg ΔTg Avg
7.13 16.88 29.77 39.01 9.75 -9.23
Potable Water Inlet/Outlet Temps
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Greywater Inlet/Outlet Temps
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APPENDIX F – Construction and Testing Pictures
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APPENDIX G – Design Criteria Table
Design Criteria Notes
Weight - What can 2 people safely carry?
- Approximate weight of hot water tank?
Volume of Waste Water &
Potable Water
- Typical discharge information for devices under
consideration, including flow rates, discharge volumes,
and discharge temperatures
- Spreadsheet calculations for optimized volume ratio
(waste to potable), ranges
- Ultimate size of reservoir (roughly size of hot water tank?)
- Dimensions of a standard doorway
- Dimensions of a hot water tank
- Footprint not too big – limited space in houses?
- Height of unit – not too tall, typical ceilings, height of hot
water tank.
Reservoir
- Existing reservoirs – can we utilize already existing
reservoirs i.e. hot water tanks, oil drums, water barrels
etc.
- Thermal conductivity of reservoir material
- Corrosion (or other reactions) considerations
- Mechanical properties i.e. strength, toughness, ductility
- Use of membranes – to prevent leaks in case of
puncture/failure of reservoir
- Other considerations regarding material selection i.e. cost,
procurement
- Construction considerations i.e. is it easy to cut or drill,
will epoxies and sealants adhere to it, etc.
- Reservoir will have to be emptied for maintenance,
removal purposes – need valves for this purpose?
Internal Tubes
- Material selection
- Thermal conductivity
- Corrosion / reaction considerations
- Clogging
- Dimensions (inner & outer diameters)
- Bending radius before kink
- Heat treatments to improved bending radius before kink?
- Cost, procurement
- Formability
- Possibility of puncture or damage
- Joining considerations
- Pressure drops through tubes
- Bypass the unit? May need valves to allow for water
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flowing through tubes to bypass unit
- Need to ensure tubes can be emptied for
maintenance/removal
Hook Up
- Sewage regulations, codes, inspections required?
- Traps
- Sealants, joints
- Bypass – allow waste water to by pass unit – valve
- Sediment filter
- Material selection
- Cost, procurement
- Mechanical properties
- Temperature control – servo valve
Solid Sediment Filtration
- Sizes of sediments
- Shape, consistency of sediments
- Filter maintenance (reusable, one time use?)
- Access to filter
- Clogging potential
- Filter versus no filter (cost?)
Sanitation Control
- Jointless tubes/quality control of joints
- Antibacterial fluid medium between potable water and
waste water – conductivity
- UV filtration
- Bacteria types/mold/fungus
- Temperature of hot water tank – mixing valve to allow hot
water tank to be set at high temp, then cooled to safe
temp before sent to distribution pipes
- Spill kit, risk mitigation, external drain incase of spill
Functionality
- Clogging mitigation
- Fluid flow characteristics through unit
- Water stagnation
- Standard valves
Maintainability
- Cleaning
- Filters
- Useful life of components
- Emptying waste water and potable water
- Shut off valves
Efficiency
- Benchmarks of existing technology
- Multi-stage
- Tube routing
- Material selection
- Thermal conductivity of materials
- Volumes/flow rates optimized
- Water storage considerations
- Computed optimizations
Simplicity - No leaks
- Few or no mechanical/electrical components – passive
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device
- Simple installation/hook up procedure
- Construction should be relatively simple
Safety/Risk
- No sharp protruding edges
- Potable water contamination is not allowed
- Hook up to hot water tank
- Spill containment
- Joint protection
Environmental Impact - Material selection – harmful to environment?
- Spill impact analysis
Cost
- Material Selection
- Electricity costs
- Rate of return for owner
- Construction methods, materials
- Overall unit cost
Robustness - Mechanical protection of joints
- Will the reservoir protect any internal components
- Mounting considerations i.e. straps, bolts, ties, etc.
Insulation - Exterior reservoir insulation
- Pipe insulation for hook up, lines coming from devices to
unit
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APPENDIX H – Screening and Evaluation Matrices
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APPENDIX I – Final Concept Sketches
Concept A
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Concept F
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Concept L
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Concept M (Final Concept)