Experimental and numerical analysis of the effective parameters on desalinated water flow in a stepped solar still

Abstract

Freshwater is an essential resource due to climate change, population growth, and groundwater contamination. The seas and oceans contain a lot of valuable saltwater. One of the economic ways to convert this expensive product from salt water is to use a stepped solar still. The low efficiency of the majority of solar stills has intrigued researchers to find ways to improve their performance. In this paper, using a neural network based on experimental data, the optimal conditions to reach maximum water production have been identified. The flow rate of desalinated water, the impact of sunlight radiation, the cover tilt angle regarding the horizon, the sodium metasilicate addition to the glass cover, the distance between the glass cover and the water surface, and finally the flow rate of the cooling stream over the glass cover were examined. The results have shown that to achieve more water at higher solar radiation levels, it is necessary to increase the cover tilt angle. Also, in the same conditions, using a low amount of sodium metasilicate compared to not using it increases efficiency by 34% on average. Also, decreasing the distance between the glass cover and the water surface increases the efficiency of this equipment. It was also observed that in low solar radiation, a low cooling flow rate is needed, and in high solar radiation, a high cooling flow rate is needed for more efficiency.