Experimental study of a humidification-dehumidification desalination system with heat pump unit

In this paper, the performance of a humidification-dehumidification (HDH) desalination system with heat pump unit is experimentally investigated. The newly developed HDH system is comprised of humidifier, heat pump unit, 1st stage dehumidifier, plate heat exchanger and 2nd stage dehumidifier. The proposed system takes advantages of heat pump unit, which transfers heat to the seawater through the plate heat exchanger and absorbs heat from air through the 2nd stage dehumidifier in the meantime. Fresh water is accumulated from both the 1st stage dehumidifier and 2nd stage dehumidifier and the productivity of the proposed system is acceptable compared with other reported HDH systems and unaffected by solar radiation. The effects of seawater temperature, air temperature and air flow rate on system productivity are investigated. Seawater temperature has a positive influence on the productivity, while the effect of air temperature is insignificant. As the air flow rate increases, the productivity increases to the maximum value at a certain air flow rate and then decreases as the air flow rate still increases. The maximum productivity of the proposed system and the estimated cost of the fresh water are 22.26 kg/h and 0.051 USD/kg respectively, which are superior compared with other HDH systems.