Examining the glass angle effect on freshwater production rate in single-basin double-slope solar still as a new water technology for sustainable rural water supply in Qom province

Qom province is almost in the center of Iran and suffers from drought and water shortage. With continuous efforts made in recent years, 100% of people in cities and more than 87% of people in villages of Qom province have access to safe and sustainable drinking water. The average number of hours of sunshine in this province is approximately 2100 h per year and therefore the water evaporation rate is high. In order to use the water evaporation capacity and produce fresh water, it is important to evaluate the solar still plants performance. In this research, we investigate the effects of glass angle for a double-slope solar still by a semi-circular basin on the rate of freshwater production in Qom province. The governing equations and boundary conditions were proposed and grid-independency and validation studies were done. In addition to the different angles effect on production rate of fresh water, temperature and relative humidity contours for different drawing angles and its results were investigated. After observing the effect of glass slope on the production rate of fresh water, it was found that the rate of production escalates by an increase in slope angle while the rate of fresh water production per unit volume decreases. The water temperature is 325 K. The glass temperature is 318.5 K. The reported water production rate ( $${\dot{M}}_{\mathrm{prod}}$$ M ˙ prod ) is equal to 0.2672. Also, the average heat flux and Nusselt number on the surface of water are increased while Nusselt number per unit volume is decreased. At an angle of 20°, the freshwater production rate was 0.2155 kg m−2 h−1 and the amount of fresh water production per volume unit was 11.14 kg m−4 h−1 and was selected as the best case.