A steady-state experimental investigation of a bubble column solar desalination system for the humidification of air using direct solar thermal heating

In order to study in depth the influencing factors of water yield from solar desalination systems with direct heat bubbling humidification-dehumidification under actual weather conditions, the performance of the desalination system under steady-state conditions was experimentally studied. This paper introduces the structure of the device and its operation principle at steady state, tests the temperature and temperature characteristics of the system under the condition of stable energy supply at different powers, and studies the influence of input power, air temperature and water temperature, glass cover plate and air velocity in the tube on the water yield of the device. The experimental results show that the water temperature and air temperature of the evaporator and the condensing chamber have a linear relationship with the input power, and the water yield and power of the device have an approximate exponential relationship. Compared with the single-layer glass cover, the double-layer glass cover increased the water yield by 10.28%, 16.90% and 22.18% when the power was 1016.0w, 1221.6w and 1523.7w respectively. The higher the air velocity in the tube, the greater the water yield was. When the input power was 792.9w, 1016.0w and 1221.6w respectively, the air velocity in the tube increased from 11.6m/s to 14.9m/s, the water yield increased by 37.4%, 41.8% and 45.9% respectively, while the air velocity in the tube increased from 14.9m/s to 21.26m3/h, and the water yield increased by 9.9%, 15% and 19.3% respectively. The performance coefficient of the device was 0.91 when the device adopted double-layer glass cover, the air velocity in the tube was 21.26m3/h and the power was 1016.0w.The relative equations of heat and mass transfer of the device are listed and the related influencing factors of water yield and performance coefficient of the device and the influence of different power on water temperature and temperature are predicted theoretically by MATLAB calculation. It was found that the experimental results are basically consistent with the theoretical predictions.