Numerical simulation investigation on thermal performance of heat pipe flat-plate solar collector

Based on finite volume method, the thermal performance of three-dimensional heat pipe flat-plate solar collector is studied under steady-state. A physical model of two-phase closed thermosyphon is established by taking account of the thermal resistance networks. The temperature field of absorber plate and flow condition as well as temperature counter of the air gap between the absorber plate and glass cover of a simulation case are described. Structure parameters such as the heat pipe diameter, the evaporator length, the absorber plate thickness and the inclination angle on the thermal performance of the collector are deeply discussed and analyzed. The results show that: The heat pipe diameter of 12 mm is helpful for increasing the useful heat gain of water and instantaneous efficiency. Increasing the evaporator length can increase the average useful heat gain of water but decrease the instantaneous efficiency of the collector. Increasing the absorber plate thickness can both improve the average useful heat gain of water and instantaneous efficiency of the collector. The inclination angle between 30 and 45 is appropriate when the collector placed towards south in Nanjing of China. The research results are helpful to design and optimize the heat pipe flat-plate solar collector. (C) 2017 Elsevier Ltd. All rights reserved.