Parametric investigation of a humidification dehumidification desalination system with open-air and semi-closed seawater configurations powered by waste heat

Abstract

Humidification dehumidification processes have been extensively introduced to the field of desalination. In this paper, a water-heated humidification dehumidification desalination system (HDDS), with open-air and semi-closed seawater water configurations, is proposed to achieve the waste heat recovery. After establishing the energetic and entropic equations of the humidification dehumidification desalination system, the corresponding analysis is accomplished. Furthermore, the dependence of the desalination performance, including the water production and relevant thermal efficiency, to the effectiveness, and cycle ratio are focused. The simulation results show the peak values of water production and gained-output-ratio (GOR) emerge at the balance condition of the humidifier. Nevertheless, due to the acquisition of the negative entropy generation rate, the actual values of water production and GOR are found as 104.64 kg h –1 and 1.98. Based on the parametric analysis, it is found that a lower humidification effectiveness is beneficial to raise the actual desalination performance, while the HDDS performance will be elevated after the increase of the dehumidification effectiveness. Furthermore, the improvement of energy conversion for the current configuration is also proved in response to recover partial brine into the feed seawater.