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In this paper. a novel type of CPC-SAC is presented. A series of experiments was conducted in 2014 in Beijing. China to investigate the thermal performance of the novel SAC. The collector exhibited a stable performance during the test period. with an annual average thermal efficiency of 52%. The novel structure effectively improved the heat performance.
Based on the experimental investigations. the following conclusions can be drawn: (1) The unique form of collecting and exchanging heat did not require a circuitous flow of air into and out of the vacuum tube. which resulted in direct heat exchange between air and fins. As such. the power consumption of the fan can be decreased. Thus. the economic efficiency of the new collector was improved. (2) The theoretical calculation showed that the optical efficiency of the collector is 65.6%. The experimental investigation showed that the instantaneous efficiency of the collector can reach 62% during the test period. (3) A high Reynolds number usually results in high heat transfer coefficients and high thermal efficiencies. When the air volume flow rate decreased. the thermal efficiency decreased evidently. By contrast. a high thermal efficiency was obtained with low heat loss. (4) The test results showed that the pressure drop was less than 36.8 Pa in the 60 m3 h to 320 m h range. The friction factor correlation based on Reynolds number has been developed for the present air duct with fins of the new collector in this study. Further research is needed to optimize the structure of the fins to improve the heat transfer conditions of the collector.
