Experimental test and sensitivity analysis of performance parameters of a solar humidification–dehumidification system

Sun-powered desalination technologies, such as humidification–dehumidification (HDH), are an attractive alternative to provide freshwater in remote high-radiation climate conditions. In this work, an experimental and numerical study is presented for a solar HDH unit operating with a closed air-open water configuration with water-heated solar collectors. The numerical model shows a good agreement with experimental data for both temperature and distillate production. A new performance parameter, so-called distillate-to-irradiance ratio (DIR), is introduced, which is specifically designed to characterise solar thermal desalination systems. This parameter takes into account both solar collection and desalination processes and could be complemented with the conventional gained output ratio (GOR = M_d λ/Q_u), which involves the distillate M_d with the heat required to distillate Q_u. The validated model is used to determine the relevant operational parameters and how they influence the DIR throughout a sensitivity analysis. Feedwater to air mass flow rate ratio (MR) and solar radiation are the key parameters to predict DIR and distillate production. For the specific conditions, a maximum of DIR = 0.44 kg/kWh for a global radiation of 1,000 W/m² and a MR = 2 was found. Finally, short- and long-term correlations based on environmental conditions were developed to easily estimate the desalination potential in specific locations.