COMPARISON OF THE PERFORMANCE OF DIFFERENT SOLAR RECEIVERS BASED ON THEIR GEOMETRY AND DIMENSIONS

In this study, the thermal performance of a solar spherical concentrator located in a sample city of Shahrekord, Iran, with different cavity receivers has been investigated. For this purpose, various receivers, such as disk, hemisphere, incomplete sphere, cylindrical, conical, and spherical receivers with different sizes have been simulated. The receivers are located at the focal point of the concentrator. The amount of energy received by each receiver is calculated for various geometric sizes based on software calculations. Among the obtained results, the geometry configuration that had the highest efficiency was reported as the most appropriate condition, and then the location for the best performance of the most suitable thermally receivers in each type is found by changing the position of each receiver around the foci. A tubular heat exchanger with thermal oil as a working fluid is considered. Then, the effect of the diameter and pitch of heat transfer pipes on the temperature rise of the output working fluid is investigated by a three-dimensional CFD simulation, and then the best diameter and pitch of the pipe are calculated. Study results show that for a spherical concentrator, the highest absorption of solar energy is achieved by receivers with spherical, cone, cylindrical, and imperfect sphere geometry, respectively. The heat exchanger pipe with a 5 mm diameter and 20 loops have the best performance and can rise the temperature of thermal oil to 440 K. The geometries were drawn in CAD software and the analyses were done with Fluent software.