Experimental study and exergetic analysis of a CPC-type solar water heater system using higher-temperature circulation in winter

The common solar water heater system can meet low temperature requirements, but exhibits very low efficiency in attaining higher water temperatures (55–95 C). In the current paper, a compound parabolic concentrator (CPC)-type solar water heater system experiment rig with a U-pipe was set up, and its performance in meeting higher temperature requirements was investigated. The experiments were conducted in December at Hefei (31 530 N, 117 150 E), in the eastern region of China. The system showed steady performance in winter, with overall thermal efficiency always above 43%. The water in the tank was heated from 26.9 C to 55, 65, 75, 85, and 95 C. Through the experimental study and exergetic analysis of the solar water heater system, results of the five experiments showed thermal efficiency of above 49.0% (attaining 95 C water temperature) and exergetic efficiency of above 4.62% (attaining 55 C water temperature). Based on these results, the CPC-type solar water heater system with a U-pipe shows superior thermal performance in attaining higher temperatures and has potential applications in space heating, heat-powered cooling, seawater desalination, industrial heating, and so on. 2012 Elsevier Ltd. All rights reserved.