Raul Simonetti, CAREL HVAC/R Knowledge Centre Corporate Business Manager, has held a webinar organised by Centro Studi Galileo, speaking about alternative refrigerants for the air conditioning.

1. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
WATER as alternative refrigerant
for the AC of buildings
Economia circolare e soluzioni green applicate al settore HVAC/R
Raul Simonetti
26 Mar 2020

2. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.

3. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Index
1. Cooling from water evaporation
2. Direct & Indirect evaporative cooling
3. Estimations: office, locations, AHU
4. Results
5. Conclusions

4. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
1. Cooling from water evaporation

5. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Evaporative cooling
• Water evaporates naturally in contact with air
• Cooling effect:
approx. 700 Wth/(L/h) of evaporated water
Note: there are adiabatic humidifiers that use as low as 10 Wel/(L/h)
Note: electric steam systems use around 700 Wel/(L/h), i.e. the latent heat of
vaporization of water
• Evaporation generates cooling and humidification

6. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
2. Direct & Indirect evaporative
cooling

7. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
DIRECT evaporative cooling
• Supply air is humidified and cooled down (-5 K typical, more possible)
• Ideal in hot and dry climates, where the needs for humidification and
cooling coexist
Drop separator
(30 Pa dry, 70 Pa wet)Supply air

8. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
INDIRECT evaporative cooling
• Extraction air is humidified and cooled down before entering the heat
recovery system
• Supply air is not humidified, but only sensibly cooled
o Additional -3.5 K typical, more possible (@ exchanger efficiency = 73%)
• Smaller coil and smaller chiller: lower investment and running costs
Drop separators
(30 Pa dry, 70 Pa wet)
Supply air

9. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
3. Estimations: office, locations,
AHU

10. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Estimations: OFFICE
• 500 persons
• Set point: 22 °C / 71 °F, 0.0082 kgv/kgda (50 %rh)
• Supply air: 17 °C / 63 °F, 0.0074 kgv/kgda (62 %rh)
• Mon-Fri, 6am-9pm
• Sun heat gain: 65 kW

11. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Estimations: LOCATIONS
• Italy: Milan (North), Rome (Centre), Palermo (South)
• Germany: Berlin (Central Europe)
• USA: Las Vegas, NV
• For all: 1-degC bin data using ASHRAE TRY climatic databases
Note: TRY = Typical Recording Year

12. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Estimations: AHUs
SUP = 63000 m³/h
(37150 cfm)
EXT = 63000 m³/h
(37150 cfm)
Efficiency = 73%
By-pass = 0%-100%
Mix = 20%-100%
ODA = 63000 m³/h
(37150 cfm)
From "Ecodesign Impact Accounting - STATUS REPORT 2018", Annex GENERAL_1, by VHK, December 2018 (rev. Jan. 2019)
• Electricity = 0,178 €/kWh, tertiary sector, year 2015
• Gas = 0.061 €/kWh, tertiary sector, year 2015
• Water (+ sewage) = 4.09 €/m³, residential, year 2015
«Current AHU» w/o IEC
«New AHU» w/ IEC
«Current AHU» = gas
«New AHU» = DEC

13. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
4. Results

14. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Milan
Half of bins above
SUPPLY:
dehumidification has a
strong impact
DEC lowers
humidifer’s energy input

15. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Rome
Half of bins above
SUPPLY:
dehumidification has
a strong impact
DEC to lower own’s energy input

16. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Palermo
More than half of bins
above SUPPLY:
dehumidification has a
stronger impact

17. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Milan: importance of BACs!
Mix fixed @
20% ODA
Mix 20%-100%
modulating
Saving 164946 kWh
-23%
BACS = Building Automation and Control System

18. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Berlin (1/2)
Many bins below
SUPPLY: humidification
has a stronger impact

19. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Berlin (2/2)
Saving 32670 kWh
-13%

20. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Las Vegas (1/2)
ALL bins
below
SUPPLY:
DEC & IEC
save energy

21. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Las Vegas (2/2)
Saving 137486 kWh
-37%

22. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
5. Conclusions

23. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
BACs
• A modulating control algorithm paired to modulating devices delivers
substantial energy savings as it can find the best «combination» of
outputs to minimize the input energy whilst guaranteeing the set point.
At building level:
o 16%-49% (Table 24 in “Optimising the energy use of technical building systems – unleashing the power of the
EPBD’s Article 8”, by ECOFYS and WAIDE STRATEGIC EFFICIENCY LTD., 27 March 2017, EU)
o 23%-49% (Figure S.2 in “Impacts of Commercial Building Controls on Energy Savings and Peak Load Reduction”,
by PNNL’s report 25985, May 2017, USA)

24. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.
Evaporative cooling
• Water is natural & non-polluting
• INDIRECT evaporative cooling (IEC):
o Reduces the load delivered by vapor-compression cooling
o May reduce its size
• DIRECT evaporative cooling (DEC):
o Idem, but usable in warm and dry climates as it introduces humidification
o Needs additional heating before DEC

25. This document and all of its contents are property of CAREL. All unauthorised use, reproduction or distribution of this document or the information contained in it, by anyone other than CAREL, is severely forbidden.