New hybrid concentrated photovoltaic/membrane distillation unit for simultaneous freshwater and electricity production

Abstract

Traditional photovoltaic-thermal desalination systems often rely on electricity to power pumps which can reduce the amount of electricity available for other practices. The current work presents an integrated system combining a concentrator photovoltaic (CPV) with a direct contact membrane distillation (DCMD) in a single unit. Hence, it is possible to use the thermal energy generated by the CPV unit to power the DCMD unit and produce both fresh water and electricity simultaneously. A comprehensive numerical model of the proposed system is developed and validated to investigate the effects of different operating conditions on the system's performance, such as the solar concentration ratio (CR), feed Reynolds number, and feed channel aspect ratio (AR), on the system's productivity. Furthermore, a modified design is introduced in which the length of the DCMD is enlarged beyond the CPV to benefit from the excess energy within the feed water. The predicted produced flux reached ∼33.2 kg/m2 h at CR = 300, Re = 175, and AR = 2400. The modified method produced a higher flux than the original design within the same CR values. The optimum length ratio values were calculated, which were found to be 1.7, while the counter configuration was nearly 1.5.