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A do it yourself box type solar cooker

You would require:

An inner and outer Box (inner preferably of sheet metal, outer can be cardboard)

Cooking vessels, Preferably of Auminium, flat box typeInsulating material

Reflector material, (Glass mirror or Silvered polyester sheets (like used for gift

wrapping, or Aluminium foil)

Box type solar cooker is one of the simplest type of cooker which is easy to make and use. Ican cook rice, day, vegetable, heat water, fry ground nuts, and can also help you to dry

various types of food stuffs.

Basically the Box type of cooker has the following construction.

It will have two boxes, one inner and another outer.

The inner box, is generally not taller than 10 to 12 cm, but the width and breadth can be ofany dimension, a box of 60 x 60 cms serves most of the purpose. One can better results if the

inner box is made of metal sheet. If you wish to use metal sheet, you can cut a old oil tin

lengthwise and use both the halves. Clean it and paint it black inside, and they will be readywhen paint dries. (The inner box need not be tapered as shown in the diagram).

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The inner box is enclosed by a larger our box, with 5 cm space on sides and bottom. (See

diagram)The outer box can be card board, metal, wooden or plywood sheets, bricks, mud oreven bamboo mat, it is there just to hold the insulation in place. The inner box can in fact be

kept in a mud enclosure too.

The 5 cm space between inner box and our box is filled with a insulating material. For bestresults you can use, Fiber glass mats, loose fiber glass, poly urethane foam sheets

(Thermocole sheets melt, so do not use it). You can also use, rice husk, wooden shavings,

saw mill waste, or if nothing is available, small balls made of old paper will also work verywell.

The upper edge of inner box is generally covered with a double walled glass cover. The glass

used is sheet glass, generally 3 mm thick. Space between upper and lower glass is generally2.5 cm. The glass can be suitably held in position by a wooden frame. This frame has to beslightly larger than or at least as large as the opening of inner box. To seal the space between

the double walled glass cover and top of inner box, you can use felt cloth, folds of old cloth,

To make the cooking more effective, a mirror reflector is used, as shown in the diagram. The

mirror can be hinged to the our box , or to the double glass cover of inner box.

The Box cooker is now ready.

But to cook, you would need preferably flat Aluminium vessels (boxes) of 20 cm diameter

with a fitting cover. They have to be painted black from out side for better result.

You can use two large and two smaller vessels for cooking. In smaller vessels you can keep

Dal or the like.

Best paint to use is dull black, so called black board paint. If that is not available, use any

other black paint which gives dull finish, avoid paint which gives shining finish.

Now you are ready with the cooker and cooking vessels. Keep it in sun for at least a day so

that the bad smell of paint evaporates.

Now load the cooking vessels and keep them in the cooker. To load the vessel, take justsufficient quantity of rice and add just enough water for cooking, do not add more water. The

practice is that there will not be any water when rice gets cooked. This way the rice cooked

will be tastier and healthier too.

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After loading the cooker, put it in the open, out side your house, turn it in such a way that the

mirror faces the sun, and adjust the angle of mirror so that the rays are reflected into the inner

box. The box There is no need to turn the box to follow the sun. But if you do so you getbetter results.

It takes about one and a half to two hours for cooking to be complete. But you need not watchthe cooker, no crow or do will come near it, the food does not get charred. If you so desire,

can keep it on a raised platform a stool or platform made of old bricks or stone.

After cooking all that you have to do is adding salt and seasoning to the Dal or vegetables.

Box cooker was one of the first types of Solar Cookers designed by Adams in

India for the Military troops. The design was later modified by M K Gosh, and now it is

popularly known as Gosh cooker.

For further details please contact

Dr Ashok Kundapur,

Kalashree,

HayagrevaNagara,Udupi 576 102

(9880305526,

arkundapur@yahoo.com)