Exergoeconomic and exergoenvironmental evaluation of a solar-energy-integrated vacuum membrane distillation system for seawater desalination

Abstract

In this paper, exergoeconomic and exergoenvironmental analyses of a solar vacuum membrane distillation (VMD) desalination system were performed to evaluate the cost of exergy destruction and the environmental impact of each component of the desalination system. The analysis per-mits the identification and evaluation of inefficiencies in the plant as well as the determination of the most environmental friendly process components and opportunities for design improvements. The results showed that the solar collector has the largest irreversibility and cost of exergy destruction. Therefore, it is a very important component for improving solar VMD plant perfor-mance. In addition, it will be profitable to reduce exergy losses in the membrane module even at the expense of increased investment costs since the dominant factor in the total cost rate for this component is the cost of exergy destruction. Whereas, it would be advantageous to reduce capital costs in the condenser since it has a relatively high exergoeconomic performance. On the other hand, exergoeconomic factor and exergy efficiency for the heat exchanger are found to be 49.02% and 96.59%, respectively, indicating that the exergy and exergoeconomic performance of this component is satisfactory. Finally, the results revealed that the largest potential for reducing the overall environmental impact of the solar VMD system is associated with the solar collector, the membrane module, the condenser, and the heat exchanger.