Numerical study of small-scale solar humidification-dehumidification desalination unit

Abstract

A numerical study of a solar desalination system based on the humidification-dehumidification thermal process was carried out. Air humidification is carried out in the evaporator by evaporating saline water. Air dehumidification takes place in a condenser where the distilled water is recovered by cooling the moist air coming from the humidifier. To achieve proper dehumidification the countercurrent configuration is considered. Energy needed to evaporate water is provided by solar energy. This study was conducted using a one-dimensional mathematical model to simulate heat and mass transfers that occur in the evaporator and the condenser. The proposed model is based on energy and mass balances of moist air, cooling water and saline water film. The resulting differential equations of ordinary derivatives are solved using the finite difference method in an iterative scheme. The mathematical model is validated against experimental and numerical results. The effect of feed saline water and air temperature at the solar evaporator entrances as well as its insulation thickness on the distillated water production of the desalination unit is studied.