Experimental determination of convection heat transfer coefficient for eggplant, zucchini and potato using a solar cooker box-type

In this work, experimental results to determine the convection heat transfer coefficient in the cooking process of eggplant, zucchini and potato using a solar cooker box-type are presented. Experimental data of temperatures for the fluid (water), surface and central point of the vegetables were used. To determine the convection coefficient, the vegetables were modeled as cylinders and a sphere according to their forms. The temperatures evolution was defined using thermocouples located at water, surface and central point in the vegetables. In the experimental process a NI Compact Field Point was used as acquisition data system which allows measure temperatures in simultaneous form. Also, a solar simulator as source of energy for the solar cooker function was used. Using heat transfer convection equations in transitory state and the temperatures measured, the Biot number and the convection coefficient were determined. To define how the cooking process occurs, diffusivity, density and heat specific were considered. Agree to results, the highest values to convection coefficient are obtained for eggplant while the minor values correspond to potato. The experimental tests for the cooking process were done in similar conditions which allow comparing results and generating a discussion for the same ones.