Investigating the effect of various working fluids in cascade refrigeration cycle integrated with thermal desalination system

Regarding the energy and potable water crisis and many environmental problems due to the use of fossil fuels, it is necessary to utilize the waste heat of industrial equipment to produce potable water without using another energy source. The cascade refrigeration cycle is one of the widely used industrial equipment, which has valuable waste heat at a high temperature. In this research, the mentioned waste energy is used as an independent energy source to produce potable water in the thermal desalination system. The present work combines a three-effect distillation desalination system with a cascade refrigeration cycle. Along with comparing the 28 working fluid pairs, a scoring method was used to determine the best working fluid pair due to the different scenarios and priorities. The results showed that the lowest power consumption of compressors belongs to R600-R717 working fluid pair. Moreover, the highest mass flow rate of produced potable water, the lowest occupied space and the lowest related investment cost happen when R744-R600A is considered. Using the scoring method, it was determined that when all indicators are considered for selecting the working fluid pair, even in different scenarios with different priorities, the best choice is R600-R717.