Wastewater desalination system utilizing a low-temperature heat pump

A wastewater desalination system based on a low-temperature air source heat pump was developed and studied in this paper. The system consists of 2 main parts: the wastewater flow process and the heat pump cycle. A series of experiments were conducted on the system under different conditions, and the effect of the evaporation temperature was investigated. This system can reach equilibrium at any evaporation temperature using the combination of the compressor and vacuum pump. To treat wastewater with low boiling point organic matter, the system was operated at a low evaporation temperature of 48 degrees C. The organic matter remained in the concentrated wastewater, and the organic removal was approximately 97%. Three kilograms of treated water was produced in 1hour with an energy consumption of 250W. The performance ratio (PR) obtained from the experiments ranged from 4.6 to 7.3. The cost for treating 1kg of water was 0.038 yuan CNY assuming 0.5 yuan CNY per kWh at the compressor frequency of 50Hz.