Design and thermal performance evaluation of a box-type solar cooker with non-tracking planar reflectors

Abstract

SYNOPSIS A model of a box-type solar cooker employing non-tracking planar reflectors has been designed and fabricated, and its thermal performance investigated experimentally. The concentrator, consisting of two planar reflectors suitably positioned in an east-west (E-W) configuration on an inclined framework, is mounted on the box of the cooker to reflect incident solar radiation on the base absorber of the cooker. The design angle of inclination of the framework is taken equal to the latitude of the location and is adjusted seasonally. The thermal performance of the experimental solar cooker has also been compared with that of a conventional box-type solar cooker whose dimensions and make are identical to the box used with the former and which was also tested simultaneously under similar solar radiation intensity and ambient conditions. Two test standards of solar cookers have been followed for thermal performance evaluation and hence the comparative analysis. The experimental results obtained from the outdoor testing show that the concentrator solar cooker provides a stagnation temperature 15–22°C higher than that of the conventional box-type solar cooker using a booster mirror. It is also observed that the boiling point of water with the concentrator cooker is reached faster, by 50–55 minutes, than with the conventional box-type cooker using a booster mirror. It has been observed that the cooking power of the laboratory model of the solar cooker is 25–50% higher than the onventional cooker in various pre-specified test conditions. Thus, the solar cooker utilising non-tracking reflectors provides increased heat collection and faster cooking compared to the conventional box-type cooker. The results of the tests conducted at various operating conditions and modes have been analysed and discussed.