Experimental study on liquid desiccant regeneration performance of solar still and natural convective regenerators with/without mixed convection effect generated by solar chimney

Solar liquid desiccant regeneration process could passively makes full use of the air flow rate generated by a solar chimney, which is an indispensable part of a passive building. A series of experiments to investigate the performance of three different regenerators were conducted in August 2019 in Chongqing, a region in China with a hot and humid summer. The three different regenerators are the solar still, basic natural convective regenerator (NCR), and natural convective regenerator with a vertical solar chimney (NCR-SC). The improvement in mass transfer efficiency based on mixed convection generated by the solar chimney is clearly revealed. The results show that cloudy weather has a more seriously negative impact on the solar still, compared with the convective-type regenerator. Compared with the NCR, the convective mass transfer coefficient of the NCR-SC is increased by 32% on 20th August due to the mixed convection. However, this increment would be weakened in the case of high ambient wind velocity (only 16％ on 25th August). The NCR-SC has the highest solar thermal efficiencies (57.8％–64.6％), followed by those of the NCR (48.4％–58.9％), whereas the solar still has the lowest values (30.3％–38.5％).