HVAC Fundamentals
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Transcript of HVAC Fundamentals
HVACFundamentals
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Objectives
• Basic industry terms• Basics of BMS and HVAC
To gain familiarity with:
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Why have Controls and BMS ?
Safety
• of People
• of equipment
Economy
• Save money
• Use just the right amount of energy (electric power, gas etc.)
• Increase equipment life by using it efficiently
• Protect equipment and products (avoids wastage - paintings in a gallery, drug/chemical stores)
• People’s productivity
Comfort
• Too hot/cold
• Too dry/humid
• Too polluted
• “Sick Occupancy”
• Health and Safety
• 21 Deg C/ 50% RH
•24 Deg C/ 50% RH
• Enough Fresh Air
• Clean Air
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Why have Controls and BMS ?
Comfort
• Need to ADD/REMOVE heat and/or moisture
• Need to clean (filter air) and supply adequate fresh air
People lose heat (feel cold) - amount they lose depends on temperature around them - cooler it is, more heat they will lose through their skin
OR they “generate” heat (feel warm/hot - WORK TOO HARD!) - need to cool them down by reducing air temperature around them
People feel “muggy” - the air around them has too much moisture
People feel “dry” - not enough moisture in the air around them
Buildings (where people live and work) also lose or gain heat (through walls, Windows, floors, roofs, heat generating equipment e.g. VDUs, and computer equipment)
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Why have Controls and BMS ?
Safety
• Need to provide protection against equipment running “wild” / out of control
• Need to make sure people are safe at all times
Can’t have coolers or heaters (boilers) running “wild” - they might freeze up or blow up!
If too hot or cold for long period of time - affects their health
Sometimes you have special needs for process (making capsules, fiber, etc)
Hospitals may have special needs for patients / medicines / labs
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Why have Controls and BMS ?
Economy
• Use energy efficiently - use plant efficiently - make people comfortable (they will produce more???)
Electric power or fuel (gas, coal, oil) is expensive and limited (?)- need to use efficiently
Environmental issues (Clean atmosphere for the occupants)
Need to ensure maximum return on investment - prolong equipment life and get the best out of it
Increase productivity of people increased profits for offices, hotels, etc.
Ensure that products you are making/ supplying (e.g. supermarket) do not deteriorate because of bad “environment”
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• How do you heat / cool your home?
• How does the heating / cooling know when to turn on?
• How does the Hot / Chilled water turn on and off ?
You already know Controls.....
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• What does the thermostat do?
• What does the A/C do?• What does a radiator do?• .. and the time switch?
In your home
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• Larger areas to be heated or cooled therefore bigger equipment (e.g. Chillers, pumps, valves)
• Different types heating/cooling equipment are used.• Operational needs are different e.g.
• different areas of the buildings occupied at different times• different areas have differing heating/ cooling requirements• Central monitoring point for Building Energy Management
System
Air-conditioning in large buildingsBasic issues are same - Comfort, Safety, Economy, BUT
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• People working in the industry refer to Wet and Dry Systems in a building
Wet & Dry Systems?
Wet Systems:• Any systems to do with water e.g.
– Chillers (cool Water)– Boilers (heat water)– Pumps (makes water flow in
pipes)– Valves (regulates amount of
water flow through heating or cooling “radiators” or coils
Dry Systems:• Any systems to do with Air e.g.
– Fans (makes air flow in ducts)– Filters (clean air)– Dampers (regulates amount of
Air flow through the ducts)– Air handling units (cools,
heats, filters air - ALL IN ONE)
Need to CONTROL and/or MONITOR both Systems
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• Control and Monitor• Room (Air) temperature, humidity, ventilation• Chillers (chilled/cold water services)• Boilers (Hot water services)• Pumps• Fans• Lights• Flow
Managing large building?
• What types of buildings and facilities do you think can use controls and BMS? – Any building
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Introduce HVAC?
Heating
Increase orDecrease the water or Air Temperature
BoilersRadiatorsPumps
Ventilating
Supply right amount of
Clean fresh air
FansAir Ducts(?)Dampers(?)
Air Conditioning
ALL IN ONE - HANDLES ALL
Cool Air
Heat Air
Clean Air
Add Moisture
Remove Moisture
Move air
Recover wasted Heat
AirHandling
Unit(AHU)
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HVAC System in a Building
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Basic of Refrigeration
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Refrigerationis
COOLCOOL
How it Works
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THERETHEREIS NO COOLIS NO COOLONLY ONLY HEATHEAT
AS LONG AS THERE’S ATOMIC MOTION AS LONG AS THERE’S ATOMIC MOTION
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Cold can’tbe given to an object.
Heat must be removed. 05/0
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A Refrigeration System is a Heat Moving Machine
Condenser
Evaporator
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Typical Refrigeration System
Low Pressure VaporLow Pressure LiquidHigh Pressure LiquidHigh Pressure Vapor
Legend
Liquid Refrigerant Receiver
Evaporator
Condenser
Compressor
TX Valve
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Air Handling Unit
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Air Handling Unit
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Fan Coil Unit (FCU)
Room Units
Variable Air Volume (VAV) box
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Packaged Units
Complete Room A/C Units
Split Air Conditioning Units
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HVAC Air Systems• HVAC air systems are made up of:
• AHU - Air handling units • Dampers• Coils and Valves• Fans • Distribution ducts and terminal boxes• Pumps and Plumbing• Control devices and control loops• Unitary equipment: fan coils, perimeter
radiation, unit ventilators, unit heaters, etc.
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AHU - Components & Terminology
RAEA
OA
Return From Space
FilterCooling Coil
Heating
DA
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AHU components
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What are Functions of AHU ?• Function:
• Condition the air• Heat the air• Cool the air• Dehumidify the air• Humidify the air• Clean the air• Distribute the conditioned air into the
building space.• Commercial air handling units can be
compared to home furnaces.
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Air Handler ComponentsThe damper section :• Manually Operated for
Outside Air/Exhaust Air
• Motorized Modulating
• Motorized On/Off
• Fire Dampers – Motorized / Fuse Link Operated
Air Handler ComponentsThe fan section with
access door open.
Air Handler ComponentsFilters :Types of Air Filters Pre Filters
Fine Filters
HEPA Filters
ULPA Filters (Ultra Low Penetration Air)
Air Handler Components
• 70-80-% Efficiency .
• Can filter particles of size upto 5-10 microns.
• Reusable & Washable
PRE-Filters
Air Handler Components
•90-95 % Efficiency .
• Can filter particles of size upto 1 to 2 microns.
• Not Reusable
Fine Filters
Air Handler Components
• 99.97-% to 99.99995 % Efficiency .
• Can filter particles of size upto 0.1 to 0.3 microns.
• Used in Clean Room Applications.
•Not Reusable
High Efficiency Particulate Air Filters (HEPA)
Air Handler ComponentsThe filter section.Notice the cross stacking
of the filters to increase surface area.
Air Handler ComponentsTemperature Sensor:• Temperature sensors are used for
measurement of temperature of a Room, Air Duct, Hot /Cold Water, Outside Air etc.
• Models are available with PT1000, NTC20K, BALCO500 sensing elements.
LF20 : AIR DUCT TEMP. SENSOR (NTC 20k)
T7412 : ROOM TEMP. SENSOR (PT1000/NTC 20k)
T7413A : IMMERSION TEMP. SENSOR (PT1000)
Air Handler ComponentsRelative Humidity Sensor:• Relative Humidity sensors are used
for measurement of Relative humidity of a Room, Air Duct, Outside Air etc.
• Sensor Type : Capacitance • Combined Relative Humidity and
Temperature Sensors are available with PT1000, NTC20K, BALCO500 sensing elements.
H7015 : DUCT RELATIVE HUMIDITY SENSOR
H7012 : ROOM RELATIVE HUMIDITY SENSOR
Air Handler ComponentsDifferential Pressure
Switch:• Differential Pressure switches are
used for monitoring of Filter, Fan, Pump, Fire Damper, Water Flow, Air Flow Status of air handling systems.
DPS1000 : AIR DIFFERENTIAL PRESSURE SWITCH
TDIAP SERIS : AIR FLOW SWITCH
Air Handler ComponentsDifferential Pressure
Sensors/Transmitter:• Used for measuring diff. Pressure,
positive pressure and vacuum.
DPT1000 : AIR DIFF. PRESSURE TRANSMITTER
ST 3000 Pressure Transmitter
Air Handler ComponentsCoils :Cooling Coils Heating Coils
Coil Construction
• Copper with Aluminium fins,
• 13 Fins /inch
• Number of Rows, I.e 4/6/8 depending on the latent heat load & Bypass Factor.
Air Handler ComponentsThe coil section of a AHU.
Note:There may be a wide variety of actual configurations
Air Handler ComponentsValves & Actuators
Valve Types 2 Way or 3 Way
Actuator Types Motorised Magnetic Pneumatic
Operation On - Off,Floating, Modulating
Air Handler ComponentsEnergy Recovery :
A energy-recovery system is often used in buildings where a significant quantity of outdoor air is used. Several types of heat-recovery systems are available Heat pumps Runaround systems Rotary heat exchangers Heat pipes.
Runaround systems
Heat Wheel
AHU Coil ControlThe air handler cooling component is accomplished via chilled water coils or via a refrigerant evaporator coil absorbing heat in the air stream.
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Practical ExampleMixed Air AHU :
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Practical Example100% Outside Air AHU :
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Plant
Chiller Plant
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Chiller PlantChiller Plant systems are made up of:
– Chiller/Condenser Unit– Chilled Water Pumps– Condenser Water Pumps– Cooling Towers – Makeup Water Tank– A/C Expansion Water Tank
TRANE Chiller
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Typical Commercial Chillers
What can we control on this system?
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Chiller PlantChiller Plant Concept :
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Typical Cooling Tower
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Typical Chiller Plant
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Boiler PlantBoiler Plant systems are made up of:
– Boiler Units– Primary Pumps– Secondary Pumps
Typical Firetube Boiler
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Typical Commercial Boiler System
What can we control on this system?
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Boiler Plant
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Questions ?? 05/0
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