Solar Collectors and Solar Cooking

Solar Cooking Solar cooking is done by means of the suns UV rays. A solar cooker lets the UV light rays in and then converts them to longer infrared light rays that cannot escape. Infrared radiation has the right energy to make the water, fat and protein molecules in food vibrate vigorously and heat up. it is the suns rays that are converted to heat energy that cook the food; and this heat energy is then retained by the pot and the food by the means of a covering or lid. This occurs in much the same way that a greenhouse retains heat An effective solar cooker will use the energy of the sun to heat a cooking vessel and efficiently retain the energy (heat) for maximum cooking effectiveness.

Solar Collectors a device for extracting the energy of the sun into a more usable or storable form harvest solar energy in the form of heat (electromagnetic radiation) harvest heat by using the “greenhouse effect”  heat trapping system Use of depends on weather conditions, as well as location and orientation of the surface

Solar Cooker Types The three most common types are: heat-trap boxes curved concentrators (parabolics) panel cookers Hundreds — if not thousands — of variations on these basic types exist.

Heat-Trap Box Solar Cookers Box cookers cook at moderate to high temperatures and often accommodate multiple pots. Worldwide, they are the most widespread.

Curved Concentrator Solar Cookers “Parabolic” Curved concentrator cookers, or "parabolics," cook fast at high temperatures Require frequent adjustment and supervision for safe operation. Useful for large-scale institutional cooking.

Panel Solar Cookers Incorporate elements of box and curved concentrator (parabolic) cookers. Simple and relatively inexpensive to buy or produce.

How Solar Cookers Work Basic Principles: Fuel: Sunlight Sunlight is converted to heat energy that is retained for cooking A solar cooker needs an outdoor spot that is: sunny for several hours protected from strong wind where food will be safe.

Design of the Solar Cooker Must capture and concentrate extra sunlight One or more shiny surfaces reflect extra sunlight onto the pot or food container, increasing its heat potential.

Efficient Solar Cooking For maximum efficiency it is necessary to "track" the sun, or in other words adjust your solar cooker so that it is directly towards the sun in order to be able to better concentrate and absorb the suns rays. The more direct that the sun's rays are towards the food and cooking pot the greater the energy (heat) capacity will be from the sun's converted rays.

Constructing a Solar Cooker Materials ¼ sheet of poster board 1 ruler (metric markings) Solar cooker pattern Rubber cement Aluminum foil

Construction Procedures Trace solar cooker pattern on to poster board Transfer fold markings to poster board by extending dashed markings from pattern Using the ruler make dashed markings for the fold lines Make a dot on the poster board that is even with the bottom of the slit cutting line. To transfer slit cutting line: For each side… using ruler measure 3 cm. from the outside edge of the longest fold line on each side – make a dot Measure 1 cm from the outside of the pattern where you made the dot. Connect the two dots – this line should be approx. 4 cm. This is the only line that will be cut.

Construction Procedures Cut around the outside of the pattern drawn on the poster board The side of the solar collector with all of the markings is the back – this side will not be covered On the unmarked side: Cover with rubber cement, then adhere aluminum foil

Construction Procedures Carefully trim aluminum foil around pattern leaving approx. 1 inch of aluminum foil around the edge Carefully fold edges of aluminum foil around the back of the pattern, securing the edges with rubber cement Using a ruler – and following dashed lines, makes folds in the cooker To make slits in the solar cooker – allow your teacher to use an exacto knife to cut the list Insert each of the “ winged edges” of the cooker into the corresponding slits.