Simulation of vacuum membrane desalination within an enhanced design of compact solar water heaters

Abstract

Vacuum Membrane Distillation stands out as a solar desalination method utilizing membrane pressure differentials to evaporate seawater and collect it as fresh water. On the other hand, the new design of compact (or integrated) solar water heaters can be very suitable for Vacuum Membrane Distillation use. In the new design of solar system, its upper part, which is under buoyancy pressure, can have a very suitable space for installing the Vacuum Membrane Distillation system. The purpose of this research is to simulate the proposed design and a dynamic time-domain model was developed for comprehensive simulation, encompassing absorber plate characteristics, collector dimensions, mass flow rate, vacuum pressure reduction, the influence of increasing membrane rows, and seawater concentration. Simulation results showcase the system’s potential, yielding 57.12kg/m2/day of freshwater daily with an average gain output ratio exceeding 1.1. The estimated water production cost is 0.039USD.L-1, along with the generation of 4.3kg.kg/m2/day of chlorine and 0.037g.kg/m2/day of bromine from Mediterranean seawater. For super saline water, the projections indicate a daily production of 104.46kg.kg/m2/day of freshwater with a production cost of less than 0.01 USD/L, a GOR of 1.7, and a daily production of 37.8kg.kg/m2/day of chlorine for a collector area of 6 m2. These outcomes underscore the efficiency and economic viability of the proposed design, positioning it as a promising solution for seawater desalination challenges.