Experimental investigation on the negative effect of the external condenser on the conventional solar still performance

Abstract

This experimental study aims to reveal the negative effect of the external condenser (EC) on the conventional solar still (CSS) performance. A new EC design was proposed and integrated into a single-slope, basin type CSS. The EC's negative aspect is demonstrated through a comparative study between the CSS and the modified solar still (MSS) in the same outdoor weather conditions. The experimental results show that adding an EC to the CSS is not always positive and the still performance is closely related to the weather conditions. The EC positive effect appears in moderate weather conditions, where its contribution to improving MSS productivity reaches 29%. While in very cold or hot weather days, the EC affects adversely the still productivity, which decreases to about 16.5% against that of the CSS. It was found that the natural circulation mode (NC) is the dominant mass transfer process, which contributes by about 63% to 80% to the water vapor transfer toward the EC. The results show also that the maximum daily energy and exergy efficiencies for the MSS and CSS are 23.2% and 1.9%, respectively, while for the CSS, they are 18.25% and 2.4%, respectively.