Solar cookers & dryers part 4

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This Power point contains information about solar dryer and also explains how a solar dryer works with example ….

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  • Solar cookers & dryers part 4

    1. 1. Energy & EnvironmentThis PowerPoint presentation is developed and created By:
    2. 2. Drying food is very popular and we can use solar dryers to do this. But why do you think we need to dry food? It prevents vegetables, fruits, coffee and other crops from decaying .................................................................................................... •Drying was one of the first methods of conserving food. •Traditional methods involved putting baskets on the floor or roof. What are the problems associated with this method? The food is open to rodents, insects, dust, wind & rain..................................................................................... This often leads to contamination of the food and the spread of germs
    3. 3. So a better method is to use a solar dryer. Solar dryers use the 4 same techniques as solar cookers. What are these 4 techniques? Trap heat Warm air 10% 10% 10 % ? Hot air ? Cold airConcentrate rays ? ? Convert light energy to heat energy Greenhouse Effect
    4. 4. Here is how a solar dryer works. Fill in the gaps. Warm humid air escapes through a vent at the top. Glass container to ....................... trap heat Food to be dried allow the greenhouse and ............................... is placed on effect to take place. mesh shelvesThere are silver inside the dryer.panels on the side ofthe glass container to Hot dry air rises...........................concentrating rays. through the dryer. convert light energy to heat energy. Black Panel to ……………
    5. 5. Here are 2 examples of solar dryers. Using the previous diagram you must label what each part does. Warm humid air escapes through a vent at the top. Food to be dried is placed on mesh shelves inside the dryer. Food to be driedGlass container to is placed ontrap heat and allow mesh shelvesthe greenhouse inside the dryer.effect to take place.There are silverpanels on the side ofthe glass container toconcentrate rays Now let’s try the second Black Panel to convert light one... energy to heat energy
    6. 6. Label and explain this dryer also. Don’t forget to use these key terms: Converting Light to heat Trapping Heat Greenhouse Effect Concentrating Rays
    7. 7. Solar dryers don’t need to use all 4 of the techniques to dry food. For instance this is a tent solar dryer. Can you guess which 2 drying techniques it uses? Trapping Heat ............................. Converting light energy and ................................... to heat energy •This dryer is cheap to produce as it is made from a plastic sheet, wire mesh and bamboo. •It is very easy to construct and is also simple to use and to maintain.
    8. 8. Its now time for our next activity!

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