Mathematical modeling of solar still for desalination of seawater

Abstract

Solar still is a green apparatuses for seawater desalination that can be a replace of common method of seawater vaporization using fossil fuel and condensing it, especially in Persian Gulf with hot weather which has a high radiation power of sun in summer when drinking water resources are limited. Solar still works using solar radiation that is a renewable source of energy and reduces the production of pollutant and greenhouse gases that produced using fossil fuel in a normal process. Therefore, commercialization of solar still is in direction of sustainable development. In this article, a solar still was modeled mathematically for describing the effect of parameters on performance of this device. Energy and mass balance equations were written using lumped formulation. Set of ordinary differential and algebraic equations was solved numerically using MATLAB software. Iteration method was used for estimating implicit heat transfer coefficients that are a function of temperatures. In this model effect of water depth and different daily solar profile was studied on total amount of water production. Temperature of basin water as a function of time was obtained by changing water depth, cycle number and solar flux profile. The cycle of still process was continued for several days without any brackish water make-up. The results show that at higher water depth, nightly desalinated water production continued more than lower water depth. The model indicates that at Muscat with higher solar flux, the water production and maximum of basin water temperature are greater than Shiraz with lower solar flux. It can be concluded that the potential of commercialization of solar still in an area near the sea with high solar flux is higher. But at lower initial water depth, the amount of water production at locations with lower solar flux approaches to the locations with higher solar flux.