Science Bar

Thursday 19 November 2015

Solar Oven



solar cooker is a device which uses the energy of direct sunlight to heat, cook or pasteurize food or drink. Many solar cookers presently in use are relatively inexpensive, low-tech devices, although some are as powerful or as expensive as traditional stoves, and advanced, large-scale solar cookers can cook for hundreds of people.

Many types of solar cookers exist, including curved concentrator solar cookers, solar ovens, and panel cookers, among others.

A solar oven is turned towards the sun and left until the food is cooked. Unlike cooking on a stove or over a fire, which may require more than an hour of constant supervision, food in a solar oven is generally not stirred or turned over, both because it is unnecessary and because opening the solar oven allows the trapped heat to escape and thereby slows the cooking process. If wanted, the solar oven may be checked every one to two hours, to turn the oven to face the sun more precisely and to ensure that shadows from nearby buildings or plants have not blocked the sunlight. If the food is to be left untended for many hours during the day, then the solar oven is often turned to face the point where the sun will be when it is highest in the sky, instead of towards its current position.


It is important to reduce convection by isolating the air inside the cooker from the air outside the cooker. Simply using a glass lid on your pot enhances light absorption from the top of the pan and provides a greenhouse effect that improves heat retention and minimizes convectional loss. This "glazing" transmits incoming visible sunlight but is opaque to escaping infrared thermal radiation. In resource constrained settings, a high-temperature plastic bag can serve a similar function, trapping air inside and making it possible to reach temperatures on cold and windy days similar to those possible on hot days.


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