Performance comparison of solar cooker using different phase change materials during off sunshine hours
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Date
2019-09
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The continuous increase in the level of greenhouse gas emissions and the increase in fuel prices are the main driving forces behind efforts to more effectively utilize various sources of renewable energy. In many parts of the world, direct solar radiation is considered to be one of the most prospective sources of energy. Energy requirement for cooking accounts for 36% of total primary energy consumption in India. Hence, there is a critical need for the development of alternative, appropriate, affordable mode of cooking for use in developing countries. However, the large scale utilization of this form of energy is possible only if the effective technology for its storage can be developed with acceptable capital and running costs. Solar cooker is the best way to utilize solar energy. In the present work thermal performance of a box type solar cooker has been evaluated according to the bureau of Indian standard (BIS). The BIS suggested two test for evaluation of thermal performance. The first test is stagnation test for evaluation of first figure of merit F1.The second test is full load test for the determination of second figure of merit F2. The first figure of merit is obtained by conducting the stagnation temperature test without load for empty box type solar cooker. The first figure of merit is the ratio of optical efficiency to heat loss factor. The second figure of merit is obtained by sensibly heating a known amount of water and it is a measure of heat exchange efficiency factor of a box type solar cooker. The variation in second figure of merit is also studied by increasing load and number of pots. It is found from experimental study that second figure of merit increases with load and number of pots. The value of figure of merit imply that the cookers are identical and satisfy BIS standard. The performance comparison of solar cooker using different phase change materials during off sunshine hours is main emphasis of the present experimental study. Cookers are also studied using modified finned cooking vessel. Three different phase change materials paraffin wax, stearic acid, lauric acid are selected. It is found from experimental studies that finned cooking vessel increases efficiency and reduces the cooking time. Paraffin wax is best phase change material to store latent thermal energy during sunshine hours and to retrieve back its conserve energy to thermic fluid water during off sunshine hours.
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