Exergy and parametric analysis of freeze desalination with reversed vapor compression cycle

Freezing desalination is one of the recent technologies that tries to contribute in water shortage problems. The idea of desalination by freezing is quite new and still needs more deep investigation for better understanding and proposing new enhancements in the system’s technology. This paper aims to present exergy and parametric analysis for different operational parameters of a small-scale desalination by freezing unit working on a reversed vapor compression cycle. Operating parameters including freezing ratio, temperature and salt concentration are investigated. These parameters variations are critical to determine the working design parameters effects on the overall cycle performance. Salinity range from 5000 to 45000 ppm was tested using a heat pump of a C.O.P range from 3.8 to 8.2. Results showed that the energy consumption for this system range was 14.5 and 68.7, kWh per meter cube water production at 5000 and 45000 ppm, respectively. Exergy analysis showed that recovering larger quantities of the expelled brine is more efficient and useful due to more contributions in increasing the energy efficiency of the operating cycle. The proposed system proved to give higher thermal efficiency compared to alternative desalination systems such as reverse osmosis with membranes or flash systems. The system recorded a high thermal efficiency of 44% at 25 °C and 50% icing ratio. The output results from the system analysis given in this paper could significantly help to implement an actual optimized desalination system working on a reversed vapor compression cycle.