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

International Journal of Research and Scientific Innovation (IJRSI) | Volume VII, Issue IV, April 2020 | ISSN 2321–2705

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

Abbas Sahi Shareef¹, Farhan Lafta Rashid², Hasan Fathi Alwan^{3
1, 3}Mechanical Engineering Department, University of Kerbala-Iraq
²Petroleum Engineering Department, University of Kerbala-Iraq

Abstract: – 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.

Keywords: Distillate output, Fresh water, phase change materials, solar still.

I. INTRODUCTION

1.1 Background

Solar energy is one of the crucial sources of renewable energy which does not cause any pollution of nature. One alternative to pure water is solar distillation, which characterized by free energy, ease of use, operation and low economic cost, compared to other sources. Some improvements are made to increase efficiency and productivity by adding thermal energy storage materials or modifying the design of the solar distiller [1, 2-5]. The pure water availability decreased rapidly by the usage of water for individual living purpose. The growth of industries also mainly depends on the water. The world was surrounded by 70% of saltwater. However, a human being cannot use that saltwater directly. That is the reason led the world looked for an alternative method to produce pure water. In solar water desalination, the production rate of water quantity depends on climate and intensity of temperature level. The need to develop small-size solar distillation units is shown to be more efficient in producing pure water in residential areas. This is the purpose of research in other ways of desalination non-pure water. The essential difficulties we encounter during the use of solar energy is the method of storing during the night, used the phase change materials [6, 7-24]. The phase change materials can be utilized in the electric motors, thermal administration of computers, the thermal safeguard of electronic apparatus, and solar power stations [25]. The experimental results showed that there is a clear difference in the using of water only as of the medium of storage and used of phase change material with water as a storage medium. The investigated experiment determined the heat transfer and enthalpy change properties of the novel PCM. The results appeared that the values of normal heat transfer parameters are higher in periods of phase change compared with water. Depending on the conditions in which the temperature passes, it increases by five times. The perfect thermal storage range is overlapped between the high values of the heat transfer coefficient and the temperature separator [26].

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