Thermodynamic Analysis of Humidification-Dehumidification Desalination System with Semi-open Air Circulation

Humidification-Dehumidification (HDH) desalination is a thermal desalination method with the potential to be driven using solar heating. The HDH cycles are classified based on the arrangement of components, the nature of the flow pattern of each of the streams and the type of heating by either water or air stream. In this paper, the semi-open method for air circulation is proposed and thermodynamically analyzed. It is shown that when the water stream is heated and top temperature of system is fixed, this method is efficient for water heating cycle but not for air heating cycle. Also, it is shown that for a designed HDH at a specific mass rate ratio, regardless of the method of air circulation, the performance of HDH is fixed. Analyzing other parameters reveals that the impact ofenvironment temperature is more vital than the relative humidity of the environment on cycle performance, therefore HDH is efficient for both dry and humid climates. It was observed that there is a specific mass flow ratio for any specified system at which the performance of cycle is constant regardless of the percentage of the air leaving the dehumidifier and returning to the humidifier