Improvement in the opto-thermal performance of Indian standard solar box cooker by novel internal retrofit radiative control

Design intervention for improvement in the performance of a solar cooker is required for its mass adoption and popularization. It has remained stagnant for decades for want of a holistic tool which provides metric for prediction of its cumulative optical and thermal(opto-thermal) performance, cooking type/objectives, techno-economic feasibility and climatic impact/carbon mitigation potential. In this work assessment of effectiveness of novel design intervention through retrofitting of internal radiative control in an Indian solar box cooker, one of the most popular family cookers in India, has been investigated using available tools. The solar cooker, with the minimal design intervention, and negligible cost implication shows an improvement of 6.74%, and 6.86% in the values of figures of merit, F₁ and F₂, respectively, used for the thermal performance evaluation. Here, the standard test procedure for figures of merit mainly accounts for the thermal aspect of the performance as it excludes the use of external booster reflector. Alternatively, the Cooker opto-thermal ratio (COR), a parameter measuring opto-thermal performance, shows a 1.25-fold increase. The retrofitted reflectors enhance localised targeted absorption and reduce thermal losses, resulting in a 25% improvement in COR. The retrofitting process is simple, and easy; and offers superior performance, favourable economics, and potential for carbon mitigation, making it highly attractive. Also, this work demonstrates COR as a tool with higher resolution enabling analysis of the impact of even minimal design intervention.