Heat pump for hot water With CO2 as a refrigerant
Sergio Giro8o Enex srl
CONVENTIONAL HEAT WITH HFC FOR HOT WATER
Heat pump combined with mixing tanks.
In convenJonal heat pumps water heaJng takes place gradually, with a temperature differenJal from 5 to 8 °C for each pass.
CONVENTIONAL HEAT WITH HFC FOR HOT WATER
SimulaJon-‐hot water temperature in the water reservoir.
Heat pump HFC, capacity 50 kW and tank 5000 liters.
CONVENTIONAL HEAT WITH HFC FOR HOT WATER
COMPARISON R134a/CO2
CO2
“AIRHEAT“ -‐ NEW HEAT PUMP WITH CO2
Heat pump combined with straJficaJon water reservoir. CO2 heat pump, capacity 30 kW and reservoir of 2500 liters.
§ The water, iniJally at 10 ° C, is heated immediately to 65 ° C and is then available at high temperature.
§ The temperature profile in the
tank varies depending on the consumpJon, but the hot water is always available at the desired temperature.
§ It is possible the accumulaJon of hot water during the night or when there is no use of hot water.
EXAMPLE OF CHARGING STORAGE VESSELS AND USE OF HOT WATER
STRATIFICATION WATER RESERVOIR Charging
Discharging – 150 litres
COMPARISON: HEAT PUMP WITH CO2 AS REFRIGERANT -‐ HFC
Benefit: § ReducJon of water storage cylinder volume § Lower electrical capacity installed; § Higher temperature of water § No risk of Legionella -‐ lower costs for sanitaJon services.
HEAT PUMP FOR HOT WATER WITH CO2 AS REFRIGERANT
Total volume of water storage
Storage temperature
Nominal Therminal capacity
Average power
consump9on
Opra9on Time
Energy consump9on
[liters] [°C] [kW] [hours] [kWh/day] [kWh/day]
Conven9onal heat pump 5000 50 50 18,0 4,7 84
Enex Airheat 2500 65 30 8,5 7,9 67
ECONOMIC ANALYSIS
MIN MAX
Energy cost €/year Energy cost €/year
HEAT PUMP -‐ 0,1 €/kWh 5.000 0,18 €/kWh 9.000
GAS BOILER 10,6 kWh/m3 0,45 €/m3 8.500 0,6 €/m3 11.500
OIL BOILER 9,5 kWh/l 1,0 €/liter 21.000 1,2€/liter 25.000
EXAMPLE: HOTEL 120 ROOMS § Water consumpJon: 80 liters/room (9,600 liters/day) + 50°C § Kitchen consumpJon: 4.500 liters/day -‐ 50°C § Water storage: 3x2.000 liters – 65°C § Installed unit: AIRHEAT 48 § Energy demand: 200.000 kWh/year § Average annual COP: 4,0
Range: § 4 sizes(18, 24, 48 and 100 kW nominal) Some available opJons: § Cold recovery § Double loop water side § ConnecJng more units in parallel (up to 12), with inverter-‐total thermal capacity up to 1200 kW (the largest capacity available)
RANGE AND AVAILABLE OPTIONS
WEB ENEX CALCULATOR LINK: http://www.enex-‐ref.com/eng/heat-‐pumps-‐selector-‐co2.aspx
§ Control Sonware specifically developed for the applicaJon
§ OpJmized operaJng parameters § Web server for remote connecJon (monitoring & technical support)
§ Measurement of effecJve capacity
HEAT PUMP CONTROL
DEFROSTING -‐ 1
Hot gas defrosJng § On demand or by Jmer § Not taking heat from hot water § Completely managed by controller § Fast, as heaJng occurs from inside of
the coil § Low energy consumpJon
DEFROSTING -‐2
START +6 MIN +12 MIN +15 MIN
CASE STUDY -‐1-‐ ITALY HOTEL – Hot water N°1 AH24 + N°1 AH48 OpJons : 130 bar +EC venJlator +ETHernet+ ”cold recovery” N°2 Puffer 2500 L – hot water N°1 Kooltank 1000 L – cold water Purpose of the unit is producJon of hot water – T=70°C -‐ recovering energy cold side in summer cooling chilled water.
Capacity at design condiJons – total installaJon (AH24 + AH48): winter summer Air temperature (source) -‐5°C 30°C (Max 45°C) Water temperature in 10°C 20°C Chilled water temperature in/out -‐-‐ 12-‐7 °C Hea9ng capacity [kW] 54 72 Hot water produc9on [liters/h] 760 1250 Cooling capacity [kW] -‐-‐ 53,5 COP hea9ng 3,2 4,0 Total COP -‐-‐ 7,0
CASE STUDY -‐2-‐ SPAIN
ELDERLY HOUSE N°1 AH24 OpJons : 130 bar +EC venJlator +ETHernet Purpose of the unit is producJon of hot water – T=65°C
Capacity at design condiJons: winter summer Air temperature (source) -‐7°C 30°C (Max 45°C) Water inlet temperature 10°C 20°C Hea9ng capacity [kW] 17,7 29,0 Hot water produc9on [liters/h]
280 552
COP hea9ng 3,2 4,0
SUMMARY
§ The use of a heat pump for hot water with CO2 is very convenient for applicaJons with high consumpJon of hot water (hotels, gyms, hospitals ...).
§ The advantage is extremely high for hotels in tourist areas (islands or mountains) where there is no natural gas distribuJon network.
§ Performances cerJfied by laboratory tests. § The recovery “cold side” increases economic
convenience. § Version for space heaJng (water 40-‐70°C) in
development.