Solar Water Filter

Desalination refers to the process of separating salt from water. Usually it is performed using large desalinators. The technology which is now coming into play is based on utilization of solar energy in desalination process. These are called as the solar desalinating units.


So basically a solar powered desalination unit produces clean water from saline water by using two methods which can be direct or indirect using solar energy which is a cleaner and better fuel as compared to others. Many countries have already adapted to these methods.

PROCESS OF DESALINATION


There are different methods of achieving desalination based on solar input. One can make use of “phase change method” by using thermal inputs or in “single phase” by making use of mechanical segregation. The phase change method uses two methods the direct method and the indirect one. Single phase on the other hand mainly uses the photovoltaic panels. It produces electricity though these photovoltaic panels.

1. In the direct method, which is employed in the small desalinating units, directly a solar collector passes the energy to the distilling unit and a single cycle carries out the process. The distillate is produced directly in the solar collector. As it is the direct method the water produced from this actually directly depends upon the amount of heating produced by the solar surface and the angle of incidence and various other factors affecting the amount of light being collected by the collector.
One such example would be of a solar still. A solar still uses the process of evaporation and condensation.

2. The indirect solar desalinating systems are different in a way that they have two separate systems. They include a solar collector which has photovoltaic cells and thermal collectors and also along with that they have separate desalination plant like any normal plant which can be multi-stage flash distillation, multiple effect evaporation, reverse osmosis or freeze separation. Here the factors that affect the production are different. They mainly include the scale of production. It generally reduces if it is implied for a large commercial purpose. Many different plant designs are being successfully implemented. The examples can be cited as multiple effect humidification, multiple effect boiling (MEB), humidification dehumidification (HDH), reverse osmosis and Freeze effect distillation.

 The combination of photovoltaic panels and reverse osmosis has been in use for a long time already.
Indirect solar desalination by a form of humidification/dehumidification is also in use in Sea house Green water.

HUMIDIFICATION-DEHUMIDIFICATION

The solar plants using humidification-dehumidification process use a multistage evaporation cycle. It almost resembles the natural water cycle occurring at a smaller scale in vitro. There follows series of condensation and evaporation cycles. During this process the water is separated from other substances. The advantages of using this other than the cost effectiveness are that it can be also used in remote areas as it is space efficient.

PERKS OF BEING ECO-FRIENDLY!

This technique of solar desalination is not new to humankind. This has been in use since time immemorial to produce freshwater and distilled water for medicinal purposes. Solar desalination is preferred over the conventional methods as this is the cost effective method and does not make use of the fossil fuels like the conventional usage of RO does. It does not produce any harmful side products and therefore protects and reduces the load on the environment to a far greater extent. This protection is secondary to the obvious benefits that we derive. The use of solar desalination plants is expected to increase in the near future with the increase in the price of the fossil fuels and the running cost of their dependent machinery.

CHALLENGES AT HAND

There are certain evitable challenges faced by the solar desalination projects. One of them is the fact that these machines are actually dependent upon the amount of heat collected by the collectors and the heat transferred by them for evaporation purposes. So the surface needs to be efficiently managed. Moreover even the angle of inclination of the sun matters which needs to properly maintain. This is not all. Apart from this a proper temperature needs to be maintained between the generator and the condenser otherwise the energy of the condenser generated after so much effort cannot be reused rather goes to waste.

Another one being the fact that sunlight is intermittent and variable even during a day, and thus becomes difficult to operate and maintain a continuous overall range. We can incorporate a thermal energy storage system to overcome this problem and it will work even on cloudy days or in hours of deficient sunlight.




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1 comment:

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