Saturday, October 8, 2011

Solar Powered Refrigerator

In third world countries solar power generators are used most commonly. These refrigerators works by harnessing the solar energy, and they preserve the goods like meat, vegetables and dairy. The much needed vaccines are also put in those refrigerators to avoid them from spoiling. The portable devices of the solar refrigerators can be constructed easily by use of simple components, and it really works in the areas where there is no electricity or unreliable power supply.

Different size and technology solar power refrigerators are being already employed in Africa. The biggest challenge for solar power refrigerators is unreliability of the sunshine, as its available several hours in the day but sometime it’s cloudy for days. So to have constant refrigeration phase change material is added.

Refrigerators Impact on Environment

Conventional refrigerators are having some dangerous impacts on the environment such as contributing to ozone layer depletion and global warming. The substances in refrigerators that cause the ozone layer depleting and global warming are chlorofluorocarbons (CFC’s), in their insulation foam or their refrigerant cycle are the most harmful.  In 80s CFC’s were banned then they were replaced with substances such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) both are the ozone depleting and contribute to global warming chemicals. Solar energy use for refrigeration tries hard to have minimum impacts on the environment.

Solar Refrigeration History

Solar refrigerators for specifically developed for developing countries. So that vaccines can be stored in proper temperature. As electricity in such countries is unreliable or some of their areas are having no electricity that’s why conventional refrigerators can’t work there.

That’s why on such places alternative refrigeration technologies are required. In beginning there gas or kerosene powered refrigerators were used to replace them for having minimum impact on the environment the solar refrigerators were introduced.

Currently there are two types of solar fridges:

  • Battery Supplemented Solar Refrigerator
  • Portable Solar Powered Fridge

Battery Supplemented Solar Refrigerator

Usually solar powered refrigerators and vaccine coolers are having combination of solar panels and lead batteries for storing energy for cloudy days and night. These solar powered fridges are expensive and also require heavy lead-acid batteries. Lead acid batteries get worse in the hot climate and sometimes are misused for other purposes. These batteries require the maintenance also, and batteries are replaced after 3 years. The batteries are disposed of as hazardous waste which can cause lead pollution.

Portable Solar Powered Fridge

A portable solar powered fridge is been produced for use in developing countries. It’s designed on the principle of evaporation. This fridge is solar powered but requires no solar panels. It can be made from common use household material. This made its cost lower so that developing world can easily access it.  Without any power consumption this fridge can keep perishable at a temperature of 6 degrees Celsius for days.

How This Fridge Works?

This fridge is made on the basic rule of evaporation, such as heat conduction and convection. There is no electricity needed for it, and can be made commonly available material in home such as cardboard, sand and recycled material.

This fridge is composed of two cylinders. The inner metal cylinder and outer cylinder can be made of anything such as wood or plastic. The metal cylinder is fitted in the outer cylinder; space is left between both cylinders. That space is filled then with organic material like sand, wool, or soil after that it’s saturated with water. Then it’s placed under the sunshine, when sun evaporates the water then the inner chamber cools reducing and maintaining the temperature at 6 degrees Celsius.

This portable solar fridge is being used in African countries like Namibia, Zambia and South Africa. Currently this fridge is used for preserving foods such as dairy and meat, yet it’s not being used for vaccines.

This fridge is limited in size, can be transported easily, no environment impacts but it do requires availability of water.


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