Evaluating the performance of eductor as vacuum generator and condenser in thermal desalination

• Eductor with chevron nozzle achieved the highest performance. • Eductor with multi-nozzle suitable for higher inlet pressure. • Eductor-based desalination enables compact alternative to traditional systems. • Experimental and CFD results validate single-nozzle eductor performance. This study presents an experimental and computational investigation of liquid eductor performance aimed at enhancing vacuum generation for desalination applications, specifically vacuum membrane distillation (VMD). Three eductor nozzle configurations were explored: single nozzle, multi-nozzle (three nozzles with varying nozzle spacing), and chevron nozzle (with tooth numbers ranging from 4 to 12). An experimental study was conducted on the single-nozzle configuration, and results were used to validate Computational Fluid Dynamics (CFD) simulations using the realizable k–ε turbulence model with enhanced wall treatment. The validated model was extended to analyze multi-nozzle and chevron designs. The multi-nozzle configuration with a nozzle spacing ratio (D n /D) of 0.23 achieved the highest vacuum generation among the multi-nozzle cases. The 10-tooth chevron nozzle achieved the best overall performance, generating a vacuum corresponding to a minimum secondary flow saturation temperature of approximately 18 °C at an inlet pressure of 230 kPa, outperforming other chevron designs (4–12 teeth). The chevron nozzle exhibited around 95 % improvement in vacuum generation, resulting in significantly lower saturation temperature of around 35 °C, and an average increase in secondary flow rate of around 37 % compared to the single nozzle. The multi-nozzle configuration demonstrated approximately 20 % improvement in vacuum generation relative to the single nozzle. This work introduces and evaluates chevron nozzles and systematically explores multi-nozzle configurations for the first time in the context of vacuum eductors for desalination. A case study integrating the eductor into a thermal vacuum desalination (TVD) system highlights the potential for replacing conventional vacuum pumps and condensers, leading to more compact desalination setups. These findings emphasize the critical role of nozzle design in optimizing vacuum generation, lowering saturation temperatures, and improving performance in eductor-driven desalination systems. Future work will extend this research to two-phase flow dynamics for desalination applications.