Thermal performance comparison of line- and point-focus solar concentrating systems: Experimental and numerical analyses

The purpose of this study was to analyze and compare the thermal performances of a line-focus and a point-focus solar concentrators (LFSC and PFSC, respectively) under similar operating and weather conditions in South Korea. Both concentrator systems had Fresnel lenses of the same surface area. To reduce heat loss, absorber pipes of the LFSC and PFSC systems were covered with borosilicate glass tube and foamed polyethylene insulation, respectively. Collector temperature (inlet and outlet temperature differential), collected energy, and thermal efficiency over experimental test time were calculated while the solar radiation, volumetric flow rate, and inlet temperature of the thermal fluid were varied. Good harmony was observed between the experimental and predicted results. Calibration of the both models reduced the deviation between the experimental and predicted temperature results compared to the uncalibrated models. Although both solar collectors showed similar trends in the variations of the average efficiency and total collected energy, these parameters were about 7% and 8% higher, respectively, in the PFSC compared to the LFSC. Overall, the results indicate that the PFSC performs slightly better than the LFSC in terms of the thermal efficiency, total collected energy, and heat loss. (C) 2016 Elsevier Ltd. All rights reserved.