Experimental study on productivity intensification of HDH desalination unit utilizing two-stage dehumidification

Abstract

In this study, an experimental investigation is performed on a two-stage dehumidification water desalination system utilizing a humidification-dehumidification process that has been accomplished using heat pump. The air is heated by means of heat pump condenser to increase its ability to efficiently humidify, while condensation takes place at the heat pump evaporator section. Additionally, in order to enhance the dehumidification efficiency a per-dehumidification process was performed to the humid air, using a cooling water heat exchanger and that was utilized prior to the evaporator. Raw water is sprayed at a constant flow rate of 2.2 L/min using cross, counter, and parallel flow spraying systems. The mass flow ratio between water and air is varied from 0.091 to 0.14 via the change in the air flow rate. The inlet cooling water temperature of the heat exchanger dehumidifier is changed from 15 to 25°C. Results of the experiments showed that the parallel flow spraying system has the highest productivity in both single and two stage dehumidification with a productivity of 2.34 L/h and 4.44 L/h respectively. The results show an extra ordinary influence of the heat exchanger on productivity intensification. The maximum specific productivity including all power consumption elements is 2.02 L/kWh.