Box type Solar Cooker

 

The principal of operation of box type solar cooker is illustrated in fig 2.4. The solar rays penetrate through the glass covers and absorbed by a blackened metal tray kept inside the solar box. The solar radiation entering the box are of short wave length. Two glass covers are provided to minimize the heat loss. The loss due to convection is minimized by making the box air tight by providing a rubber strip all around between the upper lid and the box.

 

Figure 2.4 – Box Type Solarcooker

Insulating materials like glass wool, saw dust or any other material is filled in the space between blackened tray and outer cover of the box. This minimize heat loss due to conduction with type of cooker is placed in the sun the blackened surface starts absorbing sun rays and temperature inside the box starts rising. The cooking pots, which are also blackened are placed inside with food material get heat energy and food will be cooked in a certain period of time depending upon the intensity of solar radiation and material of insulation provided. The amount of solar radiation intensity can be increased by provided mirror or mirrors.

The solar cooker is made up of inner and outer metal or wooden box with double glass sheet on it. The top cover contains 3mm thick two plain glasses fixed on wooden or metal frame, keeping about 25mm distance between the two. The entire top cover can be made tight with padlock hasp. Neoprene rubber sealing is provided around the contact surfaces of the glass cover and hinged on one side of the glass frame. A mechanism (guide for adjusting mirror) is provided to adjust the reflector at different angles with the cooker box when the reflector is adjusted to shine in the cooker box, 115^oC to 125^oC.Temperature is achieved inside the cooker box. Addition of the reflector is useful in cooking earlier particularly in winter. The solar cooker is able to cook about 1.25kg dry food materials, which is enough for a family of 5 to 7 persons. The total weight of the cooker is about 22kgs. Overall dimensions of a typical model are 60x60x20cm height.