Difference between revisions of "Air Source Heat Pump"
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COP<sub>ACTUAL</sub> = Heat output (kW) / Electrical power input (kW) ''… as reported'' | COP<sub>ACTUAL</sub> = Heat output (kW) / Electrical power input (kW) ''… as reported'' | ||
| − | COP<sub>CARNOT</sub> = 1 / ( 1 - T<sub>COLD</sub> / T<sub>HOT</sub> ) … T in Kelvin | + | COP<sub>CARNOT</sub> = 1 / ( 1 - T<sub>COLD</sub> / T<sub>HOT</sub> ) ''… T in Kelvin'' |
| − | + | which when expressed in Celsius and rearranged gives: | |
| − | COP<sub>CARNOT</sub> = (t<sub>HOT</sub> + 273) / (t<sub>HOT</sub> - (t<sub>COLD</sub>) … t in Celsius | + | COP<sub>CARNOT</sub> = (t<sub>HOT</sub> + 273) / (t<sub>HOT</sub> - (t<sub>COLD</sub>) ''… t in Celsius'' |
Revision as of 11:02, 4 December 2019
A simple model for estimating Air Source Heat Pump performance
The Building Research Establishment BRE Test Report carried out tests on a Mitsubishi PUHZ-W90VHA air to water heat pump and the test results presented in table 3 of that document were analysed against a reverse-Carnot cycle, which describes the maximum theoretical efficiency of ANY thermodynamic process and has the advantage that it can be calculated without any knowledge of the device, but simply from two temperatures expressed in degrees Kelvin: the cold and hot limits of the process, in this case the outside air heat source temperature and the supply temperature to hot water for space heating. So the two equations are
COPACTUAL = Heat output (kW) / Electrical power input (kW) … as reported
COPCARNOT = 1 / ( 1 - TCOLD / THOT ) … T in Kelvin
which when expressed in Celsius and rearranged gives:
COPCARNOT = (tHOT + 273) / (tHOT - (tCOLD) … t in Celsius