Experimental investigations of heat losses from a parabolic concentrator solar cooker

Abstract

The thermal performance of parabolic solar cooker, where an unglazed cooking pot is often used depends to a great extent on the prevailing wind conditions. Moreover, these types of cookers required tracking of the sun to keep the focus at the bottom of the cooking pot. This paper presents reports of the experimental investigations of heat losses from such a cooker under different prevailing weather conditions. The three components of the cooker considered for the analysis are: the absorber (cooking pot), cooking pot cover and air contained in the cooking pot. Convective heat losses are important determining factor in the performance of this type of solar cookers. Average values of convective heat losses determined are: absorber (cooking pot) to surrounding air (Qconv, a-air) is 0.244 W, cooking pot cover to surrounding air (Q_{conv, c-air}) is 0.096 W, cooking pot cover to air gap (Q_conv,c-g) is -0.005 W. Radiative heat losses from cooking pot cover to absorber (Q_rad,c-a) and absorber to sky (Q_rad,a-sky) has an average of -0.029 and 0.379 W, respectively. It is concluded that convective heat transfer losses are high for this type of solar cooker.

Keywords: Heat, parabolic, solar, beam.