Performance enhancement of a nanofluid filtered solar membrane distillation system using heat pump for electricity/water cogeneration

Abstract

Membrane distillation (MD) assisted by heat pump exhibits a favorable energy performance in water production, but it consumes huge precious electricity. In this work, a nanofluid filtered concentrating photovoltaic/thermal (CPV/T) technology is proposed to integrate with heat pump membrane distillation (HPMD) system for electricity/water cogeneration. Solar energy cascade utilization is considered in the system where electricity generated by CPV/T powers heat pump for MD heat recovery, and the collected thermal energy is used to heat seawater. A comprehensive study is carried out by establishing models of the receiver, direct contact membrane distillation (DCMD) and heat pump to investigate the performance of the nanofluid filtered solar membrane distillation system using heat pump. Results show that the seawater of 350.3 K is fed to the DCMD module while the electrical efficiency is above 12.2%. MD parametric analysis and equivalent specific thermal energy consumption (eSTEC) optimization are performed. We found that HPMD operates at the lowest eSTEC of 607.8 kWh·m−3 at heating temperature of 338 K and feed flow rate of 0.04 kg s−1. An overall system efficiency of 61% is obtained, and the comparison of permeate flux and energy consumption demonstrates advantages of the proposed system over other hybrid MD technologies.