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| How does a HPWH
work? |
Heat pump is
a promising technology that uses the same mechanical principles
as refrigerators and air conditioners to generate hot water.
Unlike conventional electricity and fossil-fuel-fired water
heaters, heat pump takes heat from the surrounding air/water/soil and transfer
it to the water in the tank. |
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The heat pump works by taking heat
from the surrounding air/water/soil and using it to heat low pressure liquid
refrigerant in the heat pump¡¯s evaporator, vaporizing the liquid.
The refrigerant then passes through the compressor, which raises
the refrigerant pressure and thus the temperature as well. The
heated refrigerant gas passes through the heat pump condenser,
where it gives off its heat to the water and condenses back
into the liquid state.The liquid refrigerant now passed through
an expansion valve or capillary where the pressure is reduced and the cycle
starts over. |
Heat pumps mainly consist of a compressor,
fan (applicable to air to water), evaporator and condenser. The compressor requires
electricity to compress the refrigerant and vaporize it, and
the fan requires a small amount of electricity to continually
blow air across the evaporator coils when the unit is operating.
The only electricity cost is the operation of the compressor
and the fan in order to collect the free heat and pump it to
the hot-water. |
| Why a heat pump
in preference to a traditional water heater |
Heat Pump /Traditional
Water Heaters Economy Comparisons
Heating 1000kg water from 20oC to 55oC requires
35000Kcal |
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| Heater Type |
Coal Boiler |
Fuel Boiler |
Gas |
Resistance |
Electric-boosted Solar |
HPWH |
| Energy Source |
Coal |
Diesel |
Gas |
Electricity |
Solar & Electricity |
Electricity & Air |
| Pollution |
Very High |
High |
Moderate |
None |
None |
None |
| Life Span |
5 years |
8 years |
8 years |
8 years |
8 years |
15 years |
Hazard
|
Moderate |
High |
Very High |
Moderate |
Moderate |
None |
| Fuel Value |
5000kcal/kg |
8550kcal/kg |
26000kcal/m3 |
860kcal/kwh |
860kcal/kwh |
860kcal/kwh |
COP value
|
0.55 |
0.65 |
0.65 |
0.96 |
3.3 |
3.8 |
Heat Value
|
2750kcal/kg |
6630kcal/kg |
16900kcal/m3 |
826kcal/kwh |
2838kcal/kwh |
3268kcal/kwh |
Unit Energy Cost
|
£¤0.70/kg |
£¤3.50/kg |
£¤12.8/m3 |
£¤0.66/kwh |
£¤0.66/kwh |
£¤0.66/kwh |
Energy Consumption
|
12.7kg |
6.3kg |
2.07m3 |
42.37kwh |
12.3kwh |
10.7kwh |
Energy Cost per ton
|
£¤8.89 |
£¤22.05 |
£¤26.51 |
£¤27.96 |
£¤8.12 |
£¤7.06 |
| Annual Energy Cost |
£¤3200 |
£¤8100 |
£¤9700 |
£¤10200 |
£¤2930 |
£¤2540 |
Annual Labor Cost
|
£¤4000 |
£¤2000 |
£¤2000 |
0 |
0 |
0 |
| Annual Operation Cost |
£¤7200 |
£¤10100 |
£¤11700 |
£¤10200 |
£¤2930 |
£¤2540 |
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Remarks:
1) 95 rainy and cloudy days per year in the case
of electric-boosted solar water heater.
2) £¤ is the symbol of China¡¯s currency RMB. Current
exchange rate is 1USD=7.91RMB.
3) Above data are based on the energy market in
Guangdong, China. The data are for reference only.
Actual cost analysis should be conducted according
to local markets.
4) According to the table:
Heat pump is even 13% more energy saving than electric-boosted
solar water heater;
Retrofitting electric-boosted solar water heating
system with heat pump-boosted system can cut operation
cost by 75%. |
|
 |
1. Easier
installation and requires much less installation space.
2. Heat pump will work at night.
3. Heat pump can deliver more hot water over
the day.
4. Heat pump works well in all weather conditions.
5. In a commercial installation of heat pump the
air duct can be connected to output of air
conditioning system to give improved performance.
6. Able to deliver free cooled air simultaneously
to satisfy additional cooling requirements.
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| Applications |
Heat pumps are ideal in
situations such as a commercial kitchen or laundry where
there is a steady simultaneous need for cool air and hot
water. They are widely used in hotels, restaurants, hospitals, underfloor house heating
and swimming pools/spas. |
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