Experimental investigation of improved parabolic trough solar collector thermal efficiency using novel receiver geometry design

Abstract

This experimental study discusses the thermal efficiency enhancement of a parabolic trough solar collector (PTSC) system using different absorber tube designs. Four different receiver tubes made from copper were designed and examined, including a single evacuated absorber tube, a double evacuated absorber tube, a loop evacuated absorber tube, and a double evacuated absorber tube with a flat plate. Two PTSC models, one representing the modified PTSC and the other for comparison, were fabricated and tested to compare the performance of absorber tubes under Hungarian weather conditions. A similarity test is verified prior the experiment to make sure that the two collectors give the same results. The results of the similarity test showed that the average efficiencies for the lower and upper collectors were 39.798% and 39.842%, respectively. The results showed that the maximum heat removal factor is obtained for 60 and 120 L/h mass flow rates were about 73.478% and 65.7048% for the case of a double evacuated absorber tube with a flat plate, respectively. Moreover, the maximum thermal efficiency of the PTSC with double-evacuated absorber tube and flat plate at 60 and 120 L/h was 52.7% and 59.05%, respectively. Conclusively, the PTSC's thermal performance using the loop-evacuated and double-evacuated absorbers with flat plates is superior to that of traditional tubes regardless of mass flow rate.

Keywords

• Parabolic trough solar collector
• Receiver geometry
• Thermal efficiency
• Experimental
• Hungary