Energetic and exergetic performance comparison of three solar cookers for developing countries

摘要

Three different domestic solar cookers are compared experimentally during water heating experiments using different loads. The solar cookers experimentally tested using energy and exergy thermal performance parameters are: a solar box cooker without a reflector, a solar box cooker with a reflector and a parabolic dish solar cooker. The rate of heat losses is more detrimental to the performance of the parabolic solar cooker since the cooking vessel is exposed more to the ambient weather conditions. Heat losses seem to have little effect on the performance of the solar box cookers. The solar box cooker with the reflector shows the highest average energy efficiencies, which increase with the water heating load. The parabolic solar cooker shows the lowest average energy efficiencies with the lower loads, which increase to be higher than those of the solar box cooker without the reflector at the higher loads. The solar box cooker with the reflector shows the highest average energy and exergy efficiency values, which are not dependent on the water load. The parabolic dish solar cooker shows average exergy efficiencies, which increase with the water heating load. The greatest cooking potential in terms of the speed of cooking is shown by parabolic dish solar cooker. The best overall thermal performance is shown with the solar box cooker with a reflector, but its cooking speed is rather slow when compared to the parabolic dish solar cooker. The solar box cooker without the reflector shows the worst thermal performance in most of the tested parameters except for the heat losses where it shows the lowest heat loss factors for all the experimental tests.