Further investigation of simultaneous fresh water production and power generation concept by permeate gap membrane distillation system

Low energy consumption processes are of high demand for sustainable fresh water production in our current climate. This research investigates the potential of using a lab scale permeate gap membrane distillation (PGMD) technology in combined water and power production (CWP) process. The permeate gap hydraulic pressure has been controlled by considering some restrictions at the permeate line. This study explores the effect of permeate hydraulic pressure on the permeate flux and power density. The maximum hydraulic pressure obtained within this setup was around 2 bar with a polyvinylidene difluoride (PVDF) membrane. Under an optimum permeate hydraulic pressure of 1.1 bar, 12.5 kg/m2 h of permeate flux and 0.4 W/m2 of power density are recorded with the PVDF membrane sample by adjusting the inlet fluid bulk temperatures at 80 °C and 15 °C, at the hot and cold sides. The process experimental overall efficiency at the maximum power density was estimated less than 0.002%. This capacity of power generation has been also accompanied by around 50% permeate flux reduction compared to no hydraulic pressure production within the system at the same operating conditions. The ability to generate higher power density in the case of availability of advanced membranes with high wetting resistance characteristics is also theoretically evaluated in this work.