Modeling of a modified solar still system with enhanced productivity

The solar still is a sustainable device to produce potable water, especially in arid areas with abundant sunshine and low water demands. Its low productivity, however, hinders its wider application. A lightweight, black-finished, slowly rotating drum is introduced within the still to allow the formation of thin water films that evaporate rapidly. This modification notably increases productivity while maintaining the advantages of the still such as ease of handling, low-tech requirements, material availability, safe water quality, sustain ability and space conservation. In this paper, the modified still with rotating drum is studied analytically to optimize performance. A theoretical model is developed based on governing heat and mass balance equations. The governing equations are solved numerically and the model is calibrated and validated using experimental data. The built model is used to study the effects of important variables. Three empirical correlations to determine heat transfer coefficients are employed and an error analysis is conducted for each case. Results reveal that the proposed modification significantly promotes the solar still desalination technology and gives insights for better optimization of the still. Design alterations thus offer a strong potential for this old device to serve impending challenges of severe water demands. (C) 2015 Elsevier Ltd. All rights reserved.