Part 1. Non-conventional solar stills with charcoal particles as absorber medium

A solar still in which charcoal functions both as heat absorber medium and as wick has been constructed. The still presents a 15% improvement in productivity over wick-type stills, is cheap, simple to construct, and in addition has the advantages of low thermal capacity, lightweight and ease of operation. It is made of plastic outer rectangular body in which salt water is allowed to percolate through a charcoal bed of particles that extends the length of the still, and above which a glass plate is made to cover the still at an optimum distance from the charcoal bed. The still bottom is insulated by a suitable layer of sawdust and the still is mounted on a wooden frame of adjustable inclination. Factors such as size range of charcoal particles, brine flowrate, and still inclination to the horizontal have been investigated. It was found that at high flowrates both the coarse particles followed by the intermediate size gave the best productivities, whereas at moderate flowrates the finest charcoal gave the best result. At low flowrates, the three sizes gave practically comparable productivities.

It has been shown that charcoal granules can be used as absorber medium successfully instead of wick-type, black butyl rubber, or asphaltic absorbers. A 15% improvement in productivity over wick-type stills has been attained. The still is non-conventional, cheap, simple, easy to construct and operate, and is of low thermal capacity. It has also been shown that coarse charcoal granules give acceptable results at high flowrates followed by intermediate then fine granules. The still is postulated to be used in wastewater treatment coupled with production of potable water. In addition, variable bed thicknesses can be used for efficient removal of pollutants from the waste-water.