Box Type Solar Cooker

Construction of Box Type Solar Cooker
The main parts of a box type solar cooker are:

1. An insulated metal box painted black from inside.
2. A glass sheet.
3. A plane mirror as reflector.

Principle and Working of Box Type Solar Cooker
It is well known fact that a black coloured surface absorbs more heat than a white surface. So, the inner walls and bottom of metallic box to be used for making solar cooker are painted black to increase absorption of heat. This box is covered by a thick transparent sheet of glass. When the box with glass cover is placed in the sunlight, the glass cover allows the infra red rays present in sunlight to pass into the box. Most of these infra red rays are then absorbed by black surface of the box and the box becomes hot. But, after sometime when the black surface becomes hot it starts radiating out heat in the form of infra red rays. But, the glass sheet cover placed over the box does not allow the heat radiated by the black surface to go out from the box. In this way, the glass cover enables the cooker to entrap the heat inside it.

Usually, a plane mirror reflector is also attached on the top of the box. The plane mirror reflector increases the efficiency of solar cooker by reflecting more and more sunlight inside the box.

It should be noted that the temperature inside box type solar cooker can go from 100⁰C to 140⁰C within 2 to 3 hours when placed in sunlight. So, this type of solar cooker is used to cook only those food materials which require gentle heating.

Test Your Understanding and Answer These Questions:

1. What is box type solar cooker?
2. How solar cooker works?