Computational Modeling and Performance Analysis of Solar Thermal Storage Integrated with Parabolic Solar Concentrator for Cooking Application
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Date
2020-06
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Addis Ababa University
Abstract
Cooking using biomass, which is commonly practiced in developing countries, causes rampant deforestation and exposure to hazardous emission. Hence, the utilization of solar energy for cooking can be used as solution to mitigate both problems . As solar radiation is not available at every hour of the day, thermal storage is essential for availing thermal energy at the required time of use. Therefore, this work investigates the long term efficiency of the solar cooker with a parabolic concentrating collector integrated with thermal storage using a 1D finite-difference computational model was developed under the actual cooking condition. For two type thermal storages, that is sensible pebble bed thermal storage and PCM thermal storage with air as heat transfer fluid, computational modeles are developed using MATLAB programming environment. In both case, the results of the computational models were verified using xperimental test results available in articles published in reputable journals.
In first case, a cook stove of packed pebble bed thermal storage having 0.3m diameter and 0.9m height was simulated for actual charging and cooking condition using solar radiations of Addis Ababa and Semera. The simulation resulted in thermal storage capacity of 40.1 MJ during a clear day and 12.85 MJ energy during cloudy day for Addis Ababa, and 60.3 MJ and 29.47 MJ of thermal storage for clear and cloudy day of Semera, respectively. The overall cooking efficiencies of the cookstove are 30% and 22.08% under Addis Ababa climate condition and 36.6% and 31.1% under Semera climate condition for the day of the highest and the lowest solar radiation respectively using forced convection. Hence, it can be concluded that solar concentrating cookers with pebble bed thermal storage can have an overall cooking efficiency between 22% and 30% on a clear sky day when the Sun is overhead in tropical areas.
Where as for PCM thermal storage, the thermal storage capacities of 47.42 MJ and 14.59 MJ and the overall cooking efficiencies of 53.62% and 44.10% were obtained for the day of the highest and the lowest solar radiation of Addis Ababa, respectively. For highest and lowest radaition day of Semera , the thermal stoarge capacity was 65.36MJ and 38.98MJ and the overall cooking efficiencies were 51.45% and 53.16%, respectively.
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Keywords
Parabolic Solar Concentrator, Thermal Storage, Cooking Application