LAUSR

Abstract As a key component of energy absorption system, the performance of collector/evaporator directly affects the performance of the direct-expansion solar-assisted heat pump system. However, the existing researches main paid attention to the heat pump system performance using this kind of heat exchanger, while little of them are related to the heat transfer characteristics of this heat exchanger. Therefore, the heat transfer characteristics of a finned tube used in the collector/evaporator under solar radiation are theoretically analyzed in this work, the theoretical expression of finned tube temperature field is obtained, and the accuracy of the theoretical solution is validated by simulation. Theoretical study on how various factors affect heat transfer characteristics of finned tube are carried out. It is found that the heat transfer of fin unexposed to sunlight can be adversely affected by solar radiation, and with the increase of the convective heat transfer coefficient and diameter of copper tube, the negative influence of solar radiation are effectively reduced. Under larger fin height and solar radiation condition, increasing convective heat transfer coefficient on the aluminum fin surface do not increase the air heat absorbed by finned tube, but release more heat into environment. This study can theoretically guide the design and optimization of collector/evaporator.