Design, fabrication and performance analysis of an improved solar still

In this paper, a detail comparison of the design, fabrication, cost and water production analysis between an old Tubular Solar Still (TSS) and improved (new) one is presented. Since the cover material, a vinyl chloride sheet, of the old TSS was a little bit heavy, expensive and cannot be formed into a desirable size easily, a highly durable polythene film was adopted as the cover of the new TSS. The new TSS is made of cheap and locally acquisitioned lightweight materials. Consequently, the weight and cost of the new TSS were noticeably reduced and the durability was distinctly increased. A few field experiments on the new TSS were carried out in Fukui (Japan) and Muscat (Oman) and the observed results are compared with the old one. The water production flux is proportional to the temperature difference inside the still. Evaporation mass transfer coefficients (MTCs) and heat transfer coefficients (HTCs) are higher than those of condensation. Convection HTCs are much lower than those of evaporation/condensation. Finally, a linear relation is newly found between the total HTCs and MTCs.