Design, development and performance analysis of a new desalination system integrated with a low cost fabric absorber

Abstract

In the coastal region of Bangladesh salinity in water pose a serious problem. The chief difficulty in the development of appropriate water supply system for the communities in the affected area is that - deep aquifers containing sweet water are not found at all possible locations in the coastal region. [1] There is various desalination techniques- practiced all over the world but the conventional desalination process is energy intensive and will be an expensive option particularly in the rural area of Bangladesh. Solar energy on the other hand is freely available in nature in sufficient amount. Moreover, the technology involved in distillation of saline water using the solar energy is relatively simple and maintenance can be carried out by semi-skilled or unskilled operators. Therefore, in this study, an attempt has been made to develop a family size solar desalination plant with using the black cotton fabric and produce desalinated water from vapor which meets the drinking water demand in the coastal area and remote regions. In this system direct sunlight has been utilized long back for desalination of water. Solar stills are easy to construct, can be done by local people from locally available materials, simple in operation by unskilled personnel, no hard maintenance requirements and almost no operation cost. But they have the disadvantages of high initial cost, large land requirement for installation and have output dependent on the available solar radiation. In this paper presents the experimental and theoretical work, conducted to analyses the performance of modified basin type solar still, incorporating multiple low thermal inertia porous absorbers. The porous absorbers were made up of ordinary fabric (woven or nonwoven). The absorbers ensured that the absorber surface was always wet due to capillary action and there were no dry spots. Due to low thermal inertia of the porous absorber, quicker start-up times, as well as higher operating temperatures were achieved resulting in higher distillate yield. Also, the increase in the evaporation surface area further aided the performance. In order to evaluate the improvement obtained by the modification, the performance of the modified still was compared with a conventional basin type solar still of same size, under similar operating conditions on both clear and partially clear days. The results indicate that on clear days more distillate output was obtained by the modified still, whereas it was nearly more on cloudy days.