A Review on Solar Water Distillation Using Sensible and Latent Heat

摘要

Energy and water are the two major issues faced by human beings nowadays. Owing to increase in the energy costs and the adverse effect on the environment caused by the burning of fossil fuels, renewable energy sources are being used worldwide to contribute in meeting the energy demand. Renewable energy denotes a clean, nontoxic energy source that cannot be exhausted. The primary renewable energy sources are the sun, wind, biomass, tide, waves and geothermal energy. Harnessing the abundance of solar energy has been one of the most attractive energy alternatives. The development of an efficient and economical solar energy storage system is of major concern. Energy storage plays an important role in conserving available energy and improving its utilization. Electrical energy consumption varies during day time and night time. Solar energy is available only during the day. Hence its applications require efficient thermal energy storage so that the excess heat collected during sunshine hours may be stored for later use during the night time. The main problem while utilizing solar energy is its availability which is often intermittent, variable and unpredictable. These problems can be addressed by the storage of thermal energy. Thermal energy storage (TES) will improve the efficiency and output of solar power. A thermal energy storage system mainly consists of three parts, the storage medium, heat transfer mechanism and containment system. Thermal energy storage (TES) applications have significantly increased because of the increase in the energy prices and environmental regulations. Latent heat storage (LHS) is one of the efficient ways of storing thermal energy. Unlike the sensible heat storage (SHS) method, the latent heat storage method provides much higher storage density with a smaller temperature difference between storing and releasing heat. There are large numbers of phase change materials that melt and solidify at a wide range of temperatures. The reason behind using phase change materials is due to their advantages such as low cost, high storage density and isothermal operation. For the solar desalination process, they are used as a bridge to cross the gap between the energy source, the sun and the desalination unit.