Performance investigation of solar-powered direct-contact membrane distillation and humidification–dehumidification hybrid system

•An integrated DCMD–HDH system powered by an FPC was proposed.•The FPC supplied the heat energy required for the DCMD–HDH feed solution.•The FPC system afforded a maximum temperature of 78 °C (collector area = 16 m2).•The brine discharged from the DCMD was treated with the HDH system.•The effects of the feed flow rate and temperature on the distillate rate were examined. This study proposes a novel integrated direct-contact membrane distillation (DCMD) and humidification–dehumidification (HDH) desalination system driven by a solar flat-plate collector (FPC). In this approach, seawater heated by the FPC system is fed to the DCMD system to recover freshwater. The DCMD brine is subsequently processed by the HDH system to recover additional energy and produce freshwater. The DCMD system is incorporated prior to the HDH, as high concentrations of the feed solution can cause membrane fouling and pore wetting. The performance modeling of the FPC, DCMD, and HDH systems utilizing real-time solar irradiation data of Gizan city, Saudi Arabia is considered. The effects of FPC area, solar irradiation, inlet seawater temperature, feed salinity, humidifier dehumidifier effectiveness, and inlet feed flow rate on the FPC outlet seawater temperature, distillate rate (m˙d), recovery ratio (RR), and gain output ratio (GOR) are investigated. The monthly temperature of the seawater output from the FPC is in the range of 53–78 °C with a collector area of 16 m2 and inlet feed flow rate of 1.8 L/min. The highest m˙d, RR, and GOR values are 9.1 kg/h, 8.4%, and 1.3, respectively, under temperature and flow conditions of 78 °C and 1.8 L/min, respectively. [Display omitted]