Solar Cooker: Types and Principles of Operation
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Solar Cooker: Types and Principles of Operation

An article on solar cookers, how they work and their various types...

With the continuous rise in the prices of basic commodities and the increasing threat posed by the use of fossil fuel, the need to harness free and renewable energy has gained much prominence. A very promising source of such energy is the sun which virtually cost nothing and pollution-free. One of the best technologies derived from the utilization of solar energy is the solar cooker.

A solar cooker, also known as solar oven, is a device that uses heat by concentrating or intensifying the heat from sunlight. Solar cookers are generally used for cooking, drying, and pasteurization, and are a form of outdoor cooking where sunlight is available. Many organizations are advocating on the use of such device, which is usually low-cost, because it helps slow down deforestation rate as gathering of firewood for cooking is avoided.

There are several types of solar cookers based on design. There are least 65 major designs and hundreds of variations of them. They differ on the mechanism of collecting and reflecting sunlight, but the principles of operation are similar. All these devices must be able to do perform three basic functions: to concentrate sunlight, to convert light to heat, and to trap heat. Reflective mirrors of polished glass, metal, or metalized film are used to concentrate sunlight to a small cooking area, thereby increasing the heat power. On the inside of the solar cooker, a black surface which is low in emissivity is provided to further improve the conversion of light to heat. Lastly, a sealed glass cover or related mechanism is used to trap hot air inside the solar cooker. With these factors considered, solar cookers can effectively work.

Some of the more common types of solar cookers are the following:

Box Cooker

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This is the simplest cooker which is first built in 1767 by Horace de Saussure. A basic box cooker consists of an insulated container with a transparent lid normally made of glass or plastic. The lid can be removed to allow dark pots containing food to be placed inside. The box cooker can work effectively with partially overcast skies and will typically reach temperatures of 90 – 150 deg.C.

Panel Cooker

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The panel cooker uses a reflective panel to direct sunlight onto an insulated container, usually enclosed in a clear plastic bag. A very common model of this type of solar cooker is the CooKit developed in 1994 by Solar Cookers International. The CooKit is made of aluminum pasted on a corrugated cardboard which is cut and folded to shape. It is lightweight and when folded for storage only measures about three feet by four feet. In general, panel cookers can reach temperatures comparable to box cookers.

Reflector Cooker

The reflector cooker uses various concentrating geometries (dish, trough, Fresnel mirrors) to focus light on a cooking container. These cookers reach temperatures of 315 deg.C and above but require direct light to function properly and must be repositioned to track the Sun.

a. Solar Kettle

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One example of a reflector cooker is the solar kettle. Solar kettles, used to heat water to boiling point, can generate temperatures as high as 220 deg. C.

b. Parabolic Solar Cooker

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This technology uses parabolic reflectors to concentrate sunlight. Its design is somewhat complex and difficult to fabricate. It also requires more precision to focus sunlight on the cooking vessel. Hence, the cooker must be frequently adjusted to catch sunlight and supervised for safe operation. Accordingly, it has the fastest cooking time for all cookers.

c. Cookers with Spherical Reflectors

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The Solar Bowl in Auroville, India is this type of technology. Its spherical reflector focuses light along a line perpendicular to the sphere’s surface and a computer control system moves the receiver to intersect this line. It can reach temperatures up to 150 deg.C.

Hybrid Cooker

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The hybrid cooker integrates conventional electrical heating elements in its layout for used during cloudy days or night time.

Literature Cited:

Wikipedia

Solreka.com

Solarcookers.org

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Comments (12)

I've never heard of this, thanks for sharing. Very interesting!

You have done an outstanding job here.

i did this in one of my science experiments when i was in gradeschool, nakaluto naman ng itlog.. hehe

Voted up on an excellent article. Well done.

In South Africa I helped a group of unemployed people to set up a business making and selling a spherical reflector solar cooker, and taught them to make the cooker as well. The product was well received by the people in a rural area, and the business is thriving. These products work! Well done on the article. Voted up.

Interesting concepts kabayan. No carbon emissions kasi walang uling.

Such a great article.So well done too. Voted up.

Excellent discussion of this ingenious device. I'd like to try it but I doubt it would work in England.

using these solar cookers for outdoor recreation is fun. hope they become widely used soon!

Really nice share! Great illustrations and very well written. I learned something new about the solar cooker today. Thanks for sharing. Voted up!

I often cook solar. Especially cabbage and such that leave an odor in a kitchen. Solar cooking is great and does not heat the house mid summer.

Excellent and informative write-up as usual.thanks

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