Experimental investigation of a parabolic trough collector-thermoelectric generator (PTC-TEG) hybrid solar system with a pressurized heat transfer fluid

Concentrating solar power (CSP) plants that used thermal parabolic trough collectors (PTC) are the most suitable technology in the clean power production. Several efforts have been done for enhancing the performance of PTCs. In this research, a parabolic trough collector-thermoelectric generator (PTC-TEG) hybrid solar system is proposed. In this system, two approaches to enhancing efficiency were implemented and conducted, and its thermal and electrical performances were experimentally investigated. The first, the heat transfer fluid (HTF) into the absorber tube was pressurized using a pressure control unit under relative pressures of 0.3 and 0.5 bar. The second, it was proposed that a TEG module was installed on the backside of the reflector for generating the additional electrical power from the absorbed solar radiation by it. These two approaches were implemented on a parabolic trough collector was equipped with polar N-S axis and E-W tracking mechanism. The results of the thermal performance evaluation of this system showed that the thermal efficiency increased 6.88% and 14.64% by increasing the HTF pressure of 0.3 and 0.5 bar relative to conventional PTC, respectively. The generated electrical power by a series array 70 TEG module has a 0.96-1.11% contribution to the increasing total efficiency of the proposed system. By increasing the pressure of the working fluid, the rising rate of working fluid temperature increased. Generally, the total efficiency of the proposed hybrid solar system 15.75% enhanced.