Thermal Analysis of Solar Energy-driven Membrane distillation System

The growing global population and increasing pollution have led to a steady rise in the demand for clean water. Projections indicate that by 2030, nearly half of the global population will reside in regions experiencing high water stress, driven by populat ion growth and increasing water consumption. Desalination offers a potential solution to augment water supply, and many Middle Eastern countries currently depend on it to meet their water needs. Membrane distillation (MD), which primarily utilizes low-grade thermal energy, presents a promising solution to this challenge. MD is a thermally driven separation technology that operates at relatively low temperatures and pressures, making it compatible with renewable energy sources. Despite its advantages, MD faces limitations like conductive heat loss and temperature polarization, which reduce energy efficiency. This study provides a comprehensive thermal analysis of solar-driven MD system using mathematical modelling and numerical simulations to identify optimal operating parameters. System performance is evaluated by varying membrane porosity, feed and permeate flow regimes, and operating variables such as inlet temperatures and salt concentrations. Key indicators include permeate mass flux, thermal efficiency, and gain output ratio (GOR). Results showed peak flux of 85 kg/m²·hr under optimized conditions: 2 g/L feed salinity, 4.6 L/min feed flow, and 3.65 L/min permeate flow. The system maintained high salt rejection up to 100 g/L, achieving 68.75 kg/m²·hr flux at 90°C feed and 25°C permeate temperatures. Obtained maximum thermal efficiency reached 96% with a corresponding GOR of 0.66.