Experimental study on a humidification and dehumidification desalination system of solar air heater with evacuated tubes

In this paper, a small scale solar humidification–dehumidification (HDH) experimental setup based on a new kind of solar air heater with all-glass evacuated tubes is designed and tested. Firstly, a new kind of solar air heater with evacuated tubes is designed and tested for the solar HDH desalination process. The test results of solar air heater show that the cut length of efficiency and overall heat loss coefficient is 0.47 and 1.60 respectively, while air flow rate is 140m3/h. Secondly, the humidifier and dehumidifier are designed and optimized by the mathematical design methods. Finally, a desalination pilot plant is designed and built. And then, operation characteristics are tested and analyzed. Test results show that different inlet sprayed water temperature in the pad humidifier from 9°C to 27°C can effectively improve relative humidity of outlet moist air from 89% to 97% and the outlet air temperature from 35°C to 42°C. The results are valuable in the pursuit of the optimal design for a 1000L/day solar HDH desalination system with the new kind of solar air heater. •A new kind of solar air heater is designed for solar desalination process.•A series of steady stage experiment was conducted for solar air heater.•More efficient heating and humidifying processes are analyzed and developed.•Higher outlet air temp. and relative humidity can improve fresh water production.