A solar thermal experiment with parabolic dish solar cookers for developing countries

摘要

A solar thermal experiment for the thermal performance evaluation of parabolic dish solar cookers suitable for developing countries is presented. Three different solar cooking pots are compared experimentally using three different cooking fluids, namely water, sunflower oil and olive oil. The heating experiments are carried using three identical parabolic dish solar cookers. The mass of the fluid load used in the experimental tests is 2.5 kg, on each test day. The pots that are experimentally tested under Mahikeng, South Africa, conditions are a black stainless steel pot, an aluminium silver pot and a copper pot. The stainless steel black pot shows higher temperatures as compared to the other pots. Higher energy efficiency values are also obtained with the parabolic dish solar cooker using the black stainless steel pot. The absorbing colour of the cooking pot has a more significant effect on the cooking performance than thermal conductivity of the pot. The best heat transfer fluid which obtains higher temperatures and higher cooking efficiencies is sunflower oil. The aluminium silver pot shows the lowest energy efficiencies in almost of all of the experiments. For Mahikeng conditions, the greatest cooking potential in terms of the speed of cooking is shown by the black pot using sunflower oil as the heat transfer fluid. The thermal performance in the cooking experiments is affected by ambient conditions and manual solar tracking. To shorten cooking times, a larger parabolic dish solar cooker can be used.