Proposing and optimization of a parabolic trough solar collector integrated with a photovoltaic module layer

Parabolic trough collector (PTC) is a type of solar system that generates thermal energy by concentrating solar radiation on the surface of a circular receiver tube. However, the overall output of this solar system can be significantly enhanced by the integration of this system with Photovoltaic (PV) modules which is proposed and comprehensively investigated in this research using 3D validated numerical simulation. In the first step of this study, all operating parameters of the new PTC/PV system (i.e. thickness of the air gap, the glass cover thickness, copper nanoparticles mass fraction, and PV cell efficiency) are optimized by employing the Taguchi method. Afterward, it is attempted to enhance further the efficiency of the optimized PTC/PV system by rotating the receiver tube of the system and also installing metal foam inside the fluid channel of the receiver tube. According to the Taguchi method, the maximum overall performance of the PTC/PV system is 71.1%, when the glass cover thickness, air gap thickness, PV cell efficiency, and nanoparticles mass fraction are 2 mm, 10 mm, 21%, and 6%, respectively. Additionally, the numerical simulations show that rotating the receiver tube of the optimized PTC/PV system can augment the overall efficiency of the system from 71.1% to 82.5%, which is due to the improvement in heat transfer rate from the tube to the operating fluid. However, by rotating the receiver tube, the electrical efficiency of the PV cells reduces from 16.0% to 14.9%. Additionally, installing metal foam inside the receiver tube can boost the electrical and overall efficiency of the fixed PTC/PV system by approximately 2% and 13.9%, respectively. It is worth mentioning that adding foam to the rotating receiver tube declines the thermal efficiency of the system by around 0.5%.