Thermoeconomic investigation for a multi-stage solar-thermal vacuum membrane distillation system for coastal cities

There were around 55% of people living in urban areas in 2018, and 68% of the world's population is projected to live in cities by 2050. Therefore, an urban area would experience fresh water supply shortage from conventional fresh water treatment plants. Since many cities are located on the coastal area, the building type vertical desalination system, the vacuum membrane distillation integrated with solar-thermal collectors is proposed in this study. By applying a barometric water column for vacuum membrane distillation to save the vacuum pump power consumption, the gained output ratio is over 47 for a 28-stage system. The effects of design parameters including the overall areas of membrane, heat exchangers and solar-thermal collectors, and the number of stages were investigated. Results reveal that the system performance gets better with increasing stage number, albeit the area of components is increased. The economic feasibility was accessed based on the assumptions of 1 kW center dot m(-2) of solar insolation for 5 h and night time operation for 19 h. The levelized cost analysis with the real insolation data of Miami, FL resulted in 0.97 $center dot m(3). The derived results will be useful to develop an advanced solar-thermal desalination system, especially for coastal cities.

Automated summary

This study proposed a vertical desalination system integrating vacuum membrane distillation and solar-thermal collectors to address fresh water supply shortage in urban areas. Results showed that system performance improves with increasing stage number, despite the increase in component area. The economic feasibility analysis yielded a levelized cost of 0.97 $/m3 based on real insolation data, indicating potential for advanced solar-thermal desalination systems in coastal cities.