Parabolic trough photovoltaic/thermal hybrid system: Thermal modeling and parametric analysis

Combining solar energy systems that lead to the maximization of the avail solar energy have become a trend during the recent years. In this context, parabolic trough collector and solar photovoltaics are combined with each other to obtain parabolic trough Photovoltaic/Thermal hybrid system which enables simultaneous generation of electricity and production of hot water. The layout and cogeneration of the system are described comprehensively in this work. The novelty of this work is suggesting a new methodology for conducting thermal modeling of this system which is the thermal resistance analogy and simulating it using iterative procedure. Parametric analysis is carried out in order to investigate the influence of Reynolds number, receiver side length and receiver tube length and absorber thickness on the thermal and electrical performance of the system. The results show that the thermal efficiency decreases with the increase in Reynolds number, where it diminishes by 8.31% and 2.12% in the laminar and turbulent flow, respectively. However, it increases by about 35% when the receiver side length augments from 0.03 m to 0.2 m, and by 0.78% when receiver tube length increases from 4 m to 20 m. On the other hand, the electrical efficiency augments with the rise in Reynolds number where it increases by 38.25% in the laminar flow and 5.78% in the turbulent flow, while it decreases by 10.5% and 2% when the receiver side length and receiver tube length increases. Furthermore, the absorber thickness has no effect on the thermal and electrical behavior of the system where both efficiencies remains almost constant (thermal efficiency of 56.46% and electrical efficiency of 25.34%) with the increase in the absorber thickness from 0.02 m to 0.2 m.