The thermal performance of a heat pump with the panels was considered in Ref. 3. More detail analysis on a heat pump which adopted flat plate collectors was given in Ref. 4. The analysis is given here briefly. The evaporation temperature of the refrigerant in the evaporator and COP can be predicted for various weather conditions by this analysis. The analysis uses available empirical relations that COP and power consumption of the compressor, H, are functions of evaporation temperature, te, and the temperature of the circulating water at the inlet of the condenser, tw1. Thus, eqs.1 and 2 are supposed to be given.

COP = fl(te, tW:l) (1)

H = f2(te, tw,)

The power consumption of the compressor, H, and the heat collected at the evaporator, Qe, are the supplied energy to the heat pump. The net energy supplied to the heat pump system is transferred to the circulating water. Thus, denoting the heat loss from the system to the ambient by Q, the heat obtained at the condenser, Qc, is given by the following equation.

Qc = Qe + H — Q, (3)

The heat collected by the absorber is given by the following equation.

Qe = AF{S — U(te — ta)} (4)

where A is the collector area, F’ is the collector efficiency factor ta is the ambient air temperature. S is the difference between the solar radiation absorbed by the collectors and the net radiation heat loss from the collector at the ambient air temperature. U is an overall heat transfer coefficient from the collectors to the ambient air. The values of S and U are found from the weather conditions4*.

The coefficient of performance is defined by

COP = Qc / H (5)

From eqs.3 and 5, the following equation can be obtained.

Solving eqs.1,2 and 6 simultaneously, te and COP can be found.

3.1 Use of Air-Refrigerant Heat Exchanger as Evaporator

The heat transferred from the ambient air to the refrigerant for a heat exchanger is assumed to be proportional to the temperature difference between the ambient air and the refrigerant. Therefore, the following equation is given.

COP = 1 + H (ta — te) — H (7)

where K is a proportional constant.

SHAPE * MERGEFORMAT