An experimental study on a regenerative solar still with energy storage medium — Jute cloth

Abstract

This paper presents a new approach to improve the efficiency of a solar still by introducing a medium to provide large evaporation surface and utilise the latent heat of condensation. This paper deals with the experiments conducted on a conventional single slope solar still and on a regenerative solar still with jute cloth. The conventional still has been modified with the energy storage medium viz., jute cloth which is kept vertically in the middle of basin saline water and also attached with the rear wall of the still. In the solar still, the latent heat of condensation has been released from the glass cover during condensation of water vapour at the bottom surface of the glass cover. Due to poor conductivity of the glass cover, the latent heat has not been effectively transmitted to the atmosphere by convection and radiation through the glass cover. Hence the temperature of the glass cover has increased and portion of the latent heat has been accumulated in the space between the saline water and the glass cover. This accumulated latent heat has reduced the evaporation of saline water from the water surface hence reduced the still performance and efficiency. An attempt is made to utilise the maximum amount of the incident solar energy and to utilise the latent heat of condensation which is accumulated in the space between the saline water and the glass cover. To show the effectiveness of the modification, theoretical still hourly yield from the basin water and from the jute cloth is calculated using Dunkle's model. Its performance is compared with the conventional still under the same climatic condition. It is also found that there is 9% deviation from the experimental result. It is found that cumulative still yield in the regenerative still with jute cloth increases approximately by 20% and efficiency increases by 8% with low cost for this modification as the jute cloth is very cheap and easily available.