A Research on the Thermal Daily Performance of Hybrid Solar Collector with Fin-and-Tube Heat Exchanger in Winter

Abstract

A hybrid solar collector, in this study, means the flat plate solar collector that has fin-and-tube heat exchanger beneath absorbing plate. It was focused on the combination with heat pump system. Solar thermal energy obtained from the collector can be used as a heat source of evaporator of heat pump, and the C.O.P. (coefficient of performance) of heat pump can be increased because of the increment of evaporating temperature. In case of this hybrid solar collector, different with traditional collector, it can get a thermal energy from ambient air for heating circulated water when the solar radiation is not enough. Hence, the collector can supply thermal energy to evaporator of heat pump using heated water by ambient air or solar energy selectively depending on the weather. So, in this study, thermal performance of this collector on daily operation was investigated with various flow rate of water experimentally for confirming how much solar energy can be obtained by this collector in winter. As a result, maximum thermal efficiency was shown from 55% to 62% enough to make hot water according to mass flow rate even the fin-and-tube heat exchanger was installed beneath absorbing plate instead of insulator of traditional flat plate solar collector and it was increased with increment of flow rate. But the overall heat loss coefficient also increased similar with thermal efficiency and from those efficiency curves, it was confirmed that the optimal operating condition need to be investigated in the further study before applying to heat pump system.