1. Mikkelin university of applied sciences Building services
COOLING OF BUILDINGS
Kuva: Pemco
Mikkelin university of applied sciences
Building services
Principal lecturer (TkL) Aki Valkeapää
Martti Veuro, senior lecturer
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2. COOLING OF BUILDINGS
Cooling of buildings is based on atleast still compressor cycle where the cooling medium / refrigerant is evaporated (heat transfer from surroundings to the refrigerant) and condensed (heat transfer from refrigerant to the surroundings, heat is rejected) in turn.
This cycle and the required pressure difference between evaporator (low pressure) and condenser (high pressure) is maintained by the compressor.
Kuva: Danfoss
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3. COOLING OF BUILDINGS Kuvat: Danfoss, Fincoil, Coiltech 20.11.2018
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4. COOLING OF BUILDINGS Condensing pressure and
temperature in the condenser
Amount of rejected heat by
condensation of refrigerant
Saturated liquid
Pressure difference across expansion valve
Saturated vapour
Amount of heat for
evaporation of refrigerant
Evaporation pressure
and pressure
Reference: Aittomäki 2008
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5. L L+V V C B A COOLING OF BUILDINGS
COP2 (EER) = HEAT NEEDED /HEAT REJECTED = (B-C)/(A-B)
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6. - ODP(ozone depletion potential) - GWP (global warming potential)
COOLING OF BUILDINGS
refrigerants
- ODP(ozone depletion potential)
- GWP (global warming potential)
- CFC – substances (Chloro-Fluoro-Carbon), e.g. R12 (ODP=1, GWP=8100)
- HCFC -substances, e.g. R22 (ODP=0,055, GWP=1500)
-HFC -substances, R134a, R404A, R407C, R410A (ODP=0, GWP=1300…3260)
- ammonia (ODP=0, GWP=0)
- CO2 carbon dioxide (ODP=0, GWP=1)
- HC-refrigerants, e.g. isobutane R600a is common in household refrigerators (fridges)
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7. Mechanical thermostatic expansion valve
COOLING OF BUILDINGS
Mechanical thermostatic expansion valve
Lähde:Danfoss
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8. The future solutions of cooling do not seem to be simpler than today
COOLING OF BUILDINGS
Compressor cooling can be realized as a centralised or decentralised system
Centralised or decentralised cooling system can be executed either with a direct system or with an indirect system
Centralised or decentralised cooling system can be executed either with a direct condensing or with an indirect condensing
Rooms / spaces can be cooled / air conditioned with supply air or with chilled water or both of them can be used at the same time
Addition to those also there is systems like district cooling, night ventilation, utilization of ground or water “cold”, heat pumps,...
The future solutions of cooling do not seem to be simpler than today
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9. AIR CONDITIONING SYSTEM
ALTERNATIVES
COOLING SYSTEM
direct cooling – direct condensing
direct cooling – indirect condensing
indirect cooling – direct condensing
indirect cooling – indirect condensing
indirect cooling – indirect condensing + free cooling
indirect cooling – direct condensing + free cooling
indirect cooling – indirect condensing + gliding / floating condensing pressure + free cooling (?)
AIR CONDITIONING SYSTEM
cooling with supply air
cooling with chilled water (and supply air)
cooling with circulating air
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10. DECENTRALISED DIRECT COOLING
Compressor
+condenser
evaporator
Figure: Koja
Figure: Koja
vakioilmastointikone
Direct condensing
vakioilmastointikone
Indirect condensing (fluid)
split-unit
(refrigerant cycle)
Reference: Kaappola 1996
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11. (containing refrigerant)
DIRECT COOLING
Direct cooling coil
(containing refrigerant)
supply air
Expansion valve
Liquid refrigerant from the liquid tank or condenser
discharge / hot gas to the condenser
compressor
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12. heat recovery finned coil (condenser) exit air expansion valve
CENTRALISED DIRECT COOLING (cooling machine in the air handling unit AHU)
finned coil
(condenser)
Scroll-compressor
exit air
heat recovery
expansion valve
supply air
direct cooling coil
(evaporator)
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13. CENTRALISED DIRECT COOLING
compressor
(rotation speed controlled scroll-compressor)
direct cooling coil
(refrigerant)
condensing coil
(refrigerant)
Photo: Intervent
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14. DIRECT COOLING – capacity regulator by hot gas by-pass
Figure: Danfoss
Lähde: Coiltech
Reference: Seppänen 2004
Figure: Danfoss
Figure: Srcoils
Capacity regulator with a hot gas by-pass valve (9) (100% > 50%)
- hot gas is injected between thermostatic expansion valve (7) and evaporator (8) – energy is wasted, better solution would be rotation speed controlled (scroll) compressor
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15. Air cooled condensing units
A cooling system is executed with three compressor-condenser units and the direct cooling coil is divided into three horizontal sections. Refrigerating effect is controlled by the number of compressors in operation at the same time.
Air cooled condensing units
Reference: Seppänen 2004
Reference: Aittomäki 2008
Figure: Chiller Oy
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16. CENTRALISED INDIRECT COOLING CONSTANT AIR FLOW RATE
Chiller ”plant”
without separated condenser (A+B)
with a separated condenser (A+B+C) C A B
Reference: Seppänen 2004
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17. CENTRALISED INDIRECT COOLING CONSTANT AIR FLOW RATE, AIR CONDITIONING WITH CHILLED BEAMS
Iv-kone = AHU
Lauhdutin=condenser
Vesisäiliö=water tank
Vedenjäähdytin=chiller
Ilmastointipalkki=chilled beam
Kaukolämmön alajakokeskus=
District heating substation
Term.venttiili ja vesiradiaattori=
Radiator thermostat and radiator
Reference: Seppänen 2004
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18. CENTRALISED INDIRECT COOLING AIR CONDITIONING WITH FAN COILS
Figure: Chiller
Reference: Seppänen 2004
Figure: Fläktwoods
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19. CENTRALISED INDIRECT COOLING AIRCONDITIONING AND VAV (VARIABLE AIR VOLUME)
Iv-kone=air handling unit
Vedenjäähdytin=chiller
Vesisäiliö=water tank
Lauhdutin=condenser
Reference: Seppänen 2004
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20. INDIRECT COOLING cooling coil (chilled water) compressor
water or brine (liquid)
charging circuit
refrig. cycle
plate heat exchanger
(evaporator)
chilled water tank
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21. INDIRECT COOLING AND DIRECT CONDENSING WITH AIR COOLED CONDENSER
Figure: Genemco
Photo: Danfoss
compressor
condenser
refrigerant cycle
charging circuit
expansion valve
Figure: Fincoil
plate heat exchanger
(evaporation)
Figure: Danfoss
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22. INDIRECT COOLING AND DIRECT CONDENSING ”air cooled liquid chiller”, roof (outdoors) mounting
TV 1
condenser
Figure:Koja
EVAPORATOR
+27°C
+7°C
brine P1
+12°C
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23. INDIRECT CONDENSING AIR COOLED LIQUID COOLER
refrigerant cycle
Brine circuit
Plate heat exchanger
(condenser)
Figure: Fincoil
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24. CHILLER WITH FREE COOLING AND INDIRECT CONDENSINGP1
LS 1
LS 2
water
brine
TV 1 P2
brine P3
TV 3
TV 2
LS 3
Figures: Chiller
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25. INDIRECT COOLING AND INDIRECT CONDENSING WITH FREE COOLING
air cooled liquid cooler
+42°C
+36°C
Summer case = compressor cooling
+30°C P1
LS 1
LS 2
TV 3
water
+12°C
TV 1 P2
brine P3
TV 2
LS 3
+7°C
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26. INDIRECT COOLING AND INDIRECT CONDENSING WITH FREE COOLING
Air cooled liquid cooler
winter case = compressor off
temp. outdoors < +4°C
+4°C P1
LS 1
LS 2
TV 3
water
+14°C
TV 1 P2
brine P3
TV 2
LS 3
+9°C
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27. INDIRECT COOLING AND INDIRECT CONDENSING WITH FREE COOLING
air cooled liquid cooler
summer case = compressor cooling
+36°C
+42°C
+30°C
LS 3 P1
LS 1
LS 2
TV 3
water
+14°C
TV 1 P2
brine
+7°C P3
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28. INDIRECT COOLING AND INDIRECT CONDENSING WITH FREE COOLING
air cooled liquid cooler
winter case = compressor off
temp. outdoors < +4°C
+4°C
LS 3 P1
LS 1
LS 2
TV 3
water
+9°C
+14°C
TV 1
VJK P2
brine P3
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29. CHILLER 200 … 700 kW
Figure: Chiller
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30. CHILLER 1=screw compressor 2=tube bundle heat exchanger (condenser)
3=tube bundle heat exchanger (evaporator)
4=filter drier
5=solenoid valve
6=sight glass
7=expansion valve
Reference: Kaappola 2007
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31. CHILLER Tube bundle heat exchanger as condenser:
Figure: Bitzer
Tube bundle heat exchanger as condenser:
refrigerant in bundle outside tubes
brine in tubes (non freezing liquid)
Tube bundle heat exchanger as evaporator:
refrigerant in tubes
brine in bundle outside tubes (non freezing liquid)
Reference: Aittomäki 2008
Figure: SEC heat exchanger
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32. CENTRALISED INDIRECT COOLING DIRECT CONDENSING 3-port control valves
Refernce: Kaappola
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33. CENTRALISED INDIRECT COOLING DIRECT CONDENSING 2-port control valves
Reference: Kaappola
tasaussäiliö=chilled water tank
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34. CENTRALISED INDIRECT COOLING DIRECT CONDENSING chilled beam system, three port control valve
Reference: Kaappola
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35. DISTRICT COOLING Figure : Helsingin energia
jäähdytysverkko=district cooling network
kaukojäähdytyshuone=DC tech. room
jäähdytyskeskus=cooling plant
asuintalo=residential building
liiketila oy=offices and shops
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36. replaces a compressor cooling systems in a real estate
DISTRICT COOLING
replaces a compressor cooling systems in a real estate
cooling is produced centrally, distributed through pipework to the real estates and is transferred with a heat exchanger to cooling pipework in the building (compare cf. district heating)
temperatures
- primary side +8°C / +16°C (DC network temp.)
- cooling of AHU +10°C/+17°C
- fan coils +15°C/+18°C or
if condensing water from air +10°C/+18°C
- chilled beam distribution network +15°C/+18°C
secondary side with two port control valves
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37. ? DISTRICT COOLING District cooling production in Helsinki
Figure: Helsingin energia
Vapaajäähdytys=free cooling
lämpöpumppu=heat pump
absortio=absortion
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38. Heat pump, wintertime DISTRICT COOLING Figure: Helsingin energia
Meri=sea
Jätevesi= waste water
Lämmönvaihdin=heat exchanger
Figure: Helsingin energia
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39. Heat pump, summertime DISTRICT COOLING Figure: Helsingin energia
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