Enabling open sun cooling method-based estimation of effective concentration factor/ratio for concentrating type solar cookers

The solar cooker is a vital device to attain sustainable development goals. Solar concentrating cookers (SCCs) are preferred mostly for intermediate to high-temperature cooking applications. The solar flux reflected and concentrated by the reflecting surface of the collector of a particular design of SCC are mainly responsible for the heating of the cooking pot/receiver. Hence, the quantification of the concentration-effect and subsequent assessment of effectiveness and role of reflecting surface in the opto-thermal performance analysis and rating of the SCCs is an essential and critical requirement. This work proposes a thermal method to determine an Effective Concentration Ratio (C_eff.) for any design of SCC. Two thermal tests, with and without reflecting surface, were performed on the SCC. Results depict that determination of C_eff. allows the quantification of realistic concentration ratio and comments on the thermal and optical performance analysis of the SCC. The mean value of C_eff. is determined as 4.998 and the geometric concentration ratio computed to be ~ 12.35 for the SCC used in the present work. This result indicates the effectiveness of the concentrating surface. Thus, C_eff. is an effective tool to estimate the efficacy of/degradation in the performance analysis of reflecting surface of the different designs of the SCCs and can be effectively used for grading of SCCs. This method may be helpful for other solar concentrating collectors of several design configurations as well.