The effects of various types and layouts of wick materials on the thermal performance of conventional solar stills

Abstract

In this study, three identical conventional basin type solar stills were designed and constructed to experimentally investigate the effect of using different wick materials in two different layout arrangements. The solar still basin effective area was 1 m2, and the glass cover's tilted angle was fixed at 32.5o. The first solar still was used as a reference still for comparison. The second solar still had a uniform spread of the wick material sheets in the saline water, covering the total still basin area. In this case, the wick material sheets were completely immersed in the saline water. The third solar still had a specially designed set up of mesh wires. In this case, the wick materials also cover the total still basin surface area but the wick materials were partially immersed in the saline water. The mesh wire set-ups were made from twelve 5 mm diameter and 1 m long steel wires. Five types of wick materials in the form of material sheets were used: light black cotton fabric, light jute fabric, black velvet fabric, black sheer mesh fabric, and a 4 mm thick sponge sheet. Spreading the wick material sheet to cover the basin area prevented the solar radiation; instead, the solar radiation was absorbed by the saline water and the wick material, enhancing the solar still yields. The aim of adding a mesh wire is to increase the evaporation surface area relying on the capillary effect to raise the saline water to the non-immersed part of the materials. In both layout arrangements, the light black cotton fabric was the most effective material in enhancing the still productivity, with 26.9% and 20.8% for the second and third still types respectively. The sponge sheet was found to be the least effective material in enhancing the still productivity with increases of 10.3% and 6.7% for the second and third types, respectively.