Thermal analysis of a hybrid solar desalination system using various shapes of cavity receiver: Cubical, cylindrical, and hemispherical

•A hybrid solar desalination-photovoltaic system was numerically investigated.•Humidification dehumidification desalination system was considered.•Effect of different solar cavity shapes on the system performance was analyzed.•The desalination system with hemispherical cavity has shown the highest performance.•The maximum freshwater productivity equal to 19 kg/h was resulted. In this research paper, a hybrid solar desalination system has been employed. The hybrid solar desalination system includes photovoltaic thermal panels, solar dish concentrator, and humidification-dehumidification desalination unit. The humidification-dehumidification desalination unit comprises a closed-air open-water flow configuration, and the solar dish concentrators are utilized for water heating. Examination of three different shapes of cavity receiver including cylindrical, cubical and hemispherical, as the solar dish absorbers, was carried out. Thermal oil was considered as the solar working fluid. The absorbed solar heat was transferred to the desalination unit using a heat exchanger. In the hybrid solar desalination, photovoltaic panels were used to generate the required power. Water flow was considered at the back of the photovoltaic panels for preheating and improving the photovoltaic efficiency. The principal aim of the current study is to propose hybrid solar desalination system to generate power, and produce freshwater. The solar desalination's performance was examined in terms of various solar dish parameters and different humidification-dehumidification desalination parameters. Examination of various solar dish parameters, including the solar working fluid's inlet temperature and the cavity shapes, was carried out. Also, some humidification-dehumidification desalination parameters, including the water to air flow ratio and the water flow rate, were considered. The effects of these four parameters were investigated on the water production and the gain output ratio. Based on the results, it was found that there was an increase in the production of freshwater by raising the water flow rate, decreasing the solar working fluid inlet temperature and increasing the air flow rate. Besides, there was an increase in the gain output ratio by increasing the water flow rate, increasing the inlet temperature, and increasing the air flow rate. Finally, the highest freshwater production and lowest gain output ratio were resulted by the hemispherical cavity receiver.