Review on Enhancement of Fresh Water Production in Solar Still Using Phase Change materials

Solar distillation uses the heat of the sun directly in a simple piece of equipment to purify water. The equipment, commonly called as solar still, consists primarily of a shallow basin with a transparent glass cover. The sun heats the water in the basin, causing evaporation. Moisture rises, condenses on the cover and runs down into a collection trough, leaving behind the salts, minerals, and most other impurities. The only nearly inexhaustible sources of water are the oceans, which is of high salinity. However, the separation of salts from seawater requires large amounts of energy which, when produced from fossil fuels, can cause harm to the environment. Therefore, there is a need to employ environmentally friendly energy sources in order to desalinate seawater. Phase change materials (PCM’s) are widely used in different solar applications to store the solar radiations during sunny hours and releases the stored heat after sunset. Different phase change materials (Paraffin wax, ParaffinC18, Paraffin 52-58, Bees wax, Paraffin oil, Lauric acid, Stearic acid, Bitumen, Capric-palmitic, Calcium chloride hexa hydrate, Sodium Thiosulphate Penta hydrate etc.) have been used for different solar applications due to their various properties like low melting points, high heat of fusion and low cost. In solar distillation, use of PCM is simple and cost effective method to store the solar energy at high insolation hours and releases at evening/night hours. In solar distillation phase change materials help to enhance the distillate output and its performance.