Multiple vapor compressors for enhanced performance and cost savings in vacuum membrane distillation

Abstract

This study investigates the performance of a multistage vacuum membrane distillation (MSVMD) system integrated with multiple mechanical vapor compressors (MVCs) to enhance energy recovery and improve cost-effectiveness. A comprehensive analysis is conducted to evaluate key performance indicators, including system productivity, specific energy consumption (SEC), and water production cost, across six different VMD configurations. Additionally, the effects of operational parameters such as feed temperature, vacuum pressure, and compressor efficiency are examined through a detailed parametric study. Results indicate that integrating 10 MVCs with the VMD system achieves a maximum freshwater production of 1045 L/h, representing a 297 % increase compared to a system with a single MVC at a feed temperature of 90°C. The lowest SEC recorded is 78 kWh/m³ , attained using 6 MVCs with a compressor efficiency of 90 %, leading to a minimum water production cost of 6.3 $/m³ . However, further analysis reveals that while increasing the number of MVCs enhances productivity and energy efficiency, it also raises capital investment due to the high initial cost of compressors. The operating cost primarily depends on electricity consumption, while maintenance costs escalate with the number of compressors due to additional servicing requirements. A cost-benefit analysis suggests that beyond 10 MVCs, the marginal gains in productivity are offset by rising costs, indicating an optimal balance between energy savings and economic feasibility. This study provides valuable insights into the economic and operational trade-offs of integrating MVCs with VMD, offering a viable pathway for large-scale desalination and water treatment applications.