Thermal performance analysis of a parabolic trough collector based solar water heater using revolving absorber tube

• The new concept of intermittent rotation of absorber tube of parabolic trough collector was investigated. • The intermittent rotation of absorber tube tends to improve the heat generation. • Efficiency of the conventional and rotatable absorber tube type of PTC was compared. • The maximum thermal efficiency of the PTC using rotating absorber tube is 38 % higher than the conventional PTC. In this experimental investigation a novel intermittent rotation absorber tube in PTC for the application of hot water generation were developed and made a comparison between conventional method. The concave surface of the reflector is adjustable and it is roofed with aluminum foil, for the high degree of surface finish in order to reflect the solar radiation effectively and its rate of reflectivity is 0.88. Parabolic trough is designed in such a way, which tends to tilt at variant angles like 10°, 20°, 30° respectively towards North and South directions. Rotation is only about 180°, because at initial stage the absorber tube started its absorption from direct solar radiation and reflected solar radiations, though the rate of flow is very low, and the heat transfer fluid only flows at the lowermost surface of the absorber tube. Heat generated at the upper surface of the absorber tube is unused, thus the implanted the new concept of rotating the absorber tube eliminate this difficult. Based on the experimental analysis, the performance characteristics of parabolic trough concentrator were obtained and the comparison of efficiency between the conventional type of PTC and the rotatable absorber tube type of PTC is performed. It was found that, there is an increase in efficiency over certain period of time and attains the maximum efficiency of 52 % at 2:45 p.m. The comparative result analysis showed that the maximum thermal efficiency of the PTC using rotating absorber tube is 38 % higher than the conventional PTC.