Contribution to the modeling and optimization of a new solar hybrid Photovoltaic / thermal Bi-fluid collector

Abstract

The accumulation of dust on the front faces of solar panels, the rise in the operating temperature of photovoltaic cells, and the low humidity levels recorded in semi-arid regions are considered major problems affecting negatively their performance. Therefore, over time, this leads to deteriorating and damaging PV cells. Hybrid photovoltaic/thermal systems are considered among the important technologies due to their efficiency in producing mainly electrical and thermal energy. This contribution is aimed to get a new hybrid system capable to reduce the PV cell's operating temperature with the use of passive and active cooling techniques. A self-cleaning technique suitable for the front face has also been incorporated. A numerical study of optimization of the geometrical and Thermo-hydrodynamic parameters using the CFD software Ansys Fluent was performed. After the simulation and optimization process, this new hybrid system was realized and tested under real climatic conditions in the Ghardaïa region. Thus, the PV module's backside is cooled by air, and flowing a thin film of water over its front side to cool and clean the system. The numerical results show that the optimal geometric parameters of the new hybrid PV / T air system (He = 0.05 m, We = 0.3 m, Lche = 0.735 m and dafp = 0.03 m) enhancement of the average Nusselt number by about 20% compared to the case without AFP integration. Increasing the tilt angle of the PV / T air system improves the maximum flow velocity, especially for high Rayleigh number values (with and without AFP). With the use of the active air cooling technique, an improvement in the average Nusselt number was evaluated within 80% for the case of contra-current flow compared to in the co-current case. The experimental results showed a reduction of the PV module average temperature measured for the new hybrid system of around 15 °C, against the reference PV module. An improvement of approximately 5.7% in electrical efficiency compared to the reference case was obtained under the same operating conditions and at the peak of global solar irradiation, (G = 650 W / m2 ). The overall energy efficiency and the average exergy efficiency are approximately 85.3% and 14.7%, respectively. Keywords: Hybrid PV / T Bi-fluid system, Natural convection, cooling system, tilt angle, average Nusselt number, Rayleigh number, Solar heat gain, CFD, Energy performance, Experimental study, and Photovoltaic self-cleaning.