A novel vacuum membrane distillation system with water ejector: Performance assessment and optimization

A novel vacuum membrane distillation (VMD) system integrated with a water ejector is investigated in this study to enhance freshwater productivity, energy efficiency, and economic performance. The design employs a water ejector to control the vacuum in the vapor channel of the MD system. This approach significantly reduces the energy-intensive requirements typically associated with conventional vacuum pumps. Key performance indicators, including specific energy consumption (SEC), gained output ratio (GOR), and permeate flux, were analyzed using a developed mathematical model. The VMD model is validated against existing data available in the literature. A genetic algorithm (GA) was employed to identify optimal operating parameters, including feed temperature, feed flow rate, pump pressure, and membrane characteristics. The results demonstrated substantial improvements in system performance. The SEC was reduced to 720 kWh/m3, representing a 49 % energy savings, while the GOR increased to 0.9566, more than doubling that of a baseline system. The system achieved a maximum productivity of 383.9 L/h under optimal conditions. The optimized configuration yielded a unit production cost (UPC) of 20.3 $/m3, representing a 46.9 % cost reduction. These findings underscore the system's potential as an efficient and cost-effective solution for desalination, particularly in water-stressed regions. The proposed system outperforms traditional VMD systems in the literature, making it a strong candidate for scalable freshwater production.