The performance of a solar-driven spray flash evaporation desalination system enhanced by microencapsulated phase change material

Abstract

Spray flash evaporation (SFE) technology is a promising way for efficient low-temperature desalination that can utilize waste heat or solar energy as heat source. In this paper, a solar driven-SFE desalination system enhanced by latent heat fluids is presented. The NaCl aqueous solution with addition of microcapsulated phase change material (MPCM) acts as the working fluid for thermal energy storage and the SFE process. Based on the physical properties measurements of the MPCM slurry, the flash evaporation characteristics of sprayed droplets were simulated and performances of the SFE desalination system were evaluated. The simulative results reveals that the temperature drop of droplets with MPCM may slow down during flash evaporation process, due to their higher effective heat capacity. Hence, by adding MPCM with mass fraction of 0.18 into the flash evaporation solution, the water production ratio could be increased by 23.1 %, and the unit energy consumption of the system reduced by 18.3 %. Furthermore, the effects of operating pressure the chamber and inlet superheat temperature on the SFE desalination system enhanced by MPCM were discussed, providing guidance for optimum design.