Performance analysis and comparison of concentrated evacuated tube heat pipe solar collectors

Two profiles of concentrated evacuated tube heat pipe solar collectors made of single-sided and double-sided absorber have been analyzed and compared under control conditions and results presented in this paper. These innovative concentrated evacuated tube heat pipe solar collectors were experimentally tested at a tilt angle of 60 degrees to the horizontal. Using in-door solar simulated experimental conditions temperature response, collection efficiency, heat loss coefficients and energy collection rates as well as the incident angle modifier (IAM) were recorded and compared at five different transverse angles (0-40 degrees) at 10 degrees increments. The use of concentrated single-sided and double-sided absorber evacuated tube heat pipe solar collectors is seen to be feasible for integrating solar thermal energy into buildings for heating demands. The concentrated double-sided absorber evacuated tube heat pipe proves better compared to the concentrated single-sided absorber evacuated tube heat pipe solar collector due to higher outlet temperature with greater temperature differential and improved thermal performance. The integration of this innovative system implies that the number of the evacuated tube heat pipe collectors needed to attain higher temperature is reduced. Furthermore, the size of reflectors and related reflector losses are reduced due to the truncated nature of the reflectors providing a low concentration ratio. (c) 2012 Elsevier Ltd. All rights reserved.