Hybrid nanofluid filtered concentrating photovoltaic/thermal-direct contact membrane distillation system for co-production of electricity and freshwater

Abstract

The membrane distillation (MD) systems integrated with photovoltaic/thermal (PV/T) collectors can hardly obtain large permeate flux and favorable electrical performance simultaneously. Therefore, an innovative hybrid nanofluid filtered concentrating PV/T (CPV/T)-direct contact membrane distillation (DCMD) system is proposed. The novelty is that Ag/saline water nanofluid acts as a multifunctional fluid capable of absorbing solar spectrum, which cannot be efficiently utilized by solar cells, and converting it into heat to directly produce water in DCMD. Mathematical models of both nanofluid filtered CPV/T and DCMD are established to evaluate the system performance. Results indicated that nearly 70% of solar radiation is converted into useful energy by the nanofluid filtered CPV/T device. Besides, detailed parametric studies are performed to explore how the system performance is affected by the operation and design parameters. It is found that Ag/saline water nanofluid can be heated to 353 K for desalination, at which, the DCMD module can produce 26.4 kg m−2 h−1 of fresh water. Meanwhile, the electrical efficiency of the system is 12.2% and the equivalent system thermal efficiency can reach a maximum of 71.3%. Furthermore, we demonstrate that the use of Ag/saline water nanofluid as feed stream can mitigate the temperature polarization and improve DCMD performance.