Solar desalination is the desalination of water using solar energy .
The history of solar desalination begins in the early 1950s, when the possibility of using simple solar distillers for remote settlements in the desert and on the coast was studied. The cheapness of water pumps and pipes, as well as the cheapening of energy sources in the 20th century, made these projects uncompetitive. At the beginning of the 21st century, interest in research in this field reappeared. This is due to rising energy prices, depletion of artesian water and increasing pollution of water sources used.
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Solar desalination methods
Reverse Osmosis
Reverse osmosis is a method of purifying water from impurities, based on the process of diffusion . For this method, a certain pressure is created in the desalination fluid, which, through a partially permeable membrane, displaces water molecules and retains larger molecules, as well as microorganisms . This is the preferred method for desalination of large volumes of water in areas where access to electricity is restricted. Solar energy is converted into electrical or mechanical to initiate the process.
Solar multistage condensation and evaporation cycle
The solar multistage condensation and evaporation cycle (SMCEC) is a solar desalination technology using natural convection in a vertical chimney. It uses the convection effect to pass the exiting heated water vapor through the grid of the heat exchanger-condenser (through which the incoming water enters), and thus the incoming water is preheated. This increases the overall efficiency of the system.
Problems
There are two problems that stand in the way of any solar desalination project. First, the efficiency of the system is determined by the temperature difference between the evaporation and condensation zones. The first should be as hot as possible, the second - as cold as possible. At low cost, this is difficult to achieve. Secondly, the heat released by water vapor during condensation is, in fact, the energy brought into the system by the sun and can be used to good advantage. But in most existing solar distillers, it is removed as unnecessary. The problem to this day is to achieve:
- The maximum temperature difference between the evaporator and the condenser;
- Maximum reuse of condensation energy;
- The minimum cost.
Links
- The free process of turning seawater into fresh water using solar heater tools
- Concentrating Solar Power for Seawater Desalination // German Aerospace Center (DLR) 2007 (Eng.)
- CHAPTER 9 SOLAR DESALINATION // ANNUAL REVIEW OF HEAT TRANSFER XV - Begell House, 2012, ISSN: 1049–0787; ISBN 1–978–56700–311–6, pages 277-348 (English)
- Water Desalination Using Renewable Energy. Technology Brief // ETSAP, IRENA, 2012