Abstract
The purpose of this study was experimentally to investigate thermal performance of heat pipe for evacuated tubular solar collector. Two sets of evacuated tubular solar collector with different condenser shape of heat pipe were prepared. The experiments were performed under the same operating condition with an indoor testing apparatus. Also, the experiments were carried out various testing conditions including inclination, flow rate, and incident heat flux. The results of thermal performance of collector with enlarged condenser showed that $F_R({\tau}{\alpha})$ was 0.6572 and $F_RU_L$ was -2.0086 at $40^{\circ}$. And the results of thermal performance of collector with straight condenser showed that $F_R({\tau}{\alpha})$ was 0.6233 and $F_RU_L$ was -1.4996 at the same inclined angle.
