Thermal performance test models having various operational and design parameters of the solar cookers exist (Vaishya et al 1985, Mullick et al 1987, Mullick et al 1991, Habeebullah et al 1995, Funk and Larson 1998). Most of the earlier models are based on the determination of time taken for cooking various types of food articles (Yadav et al 1987, Khalifa et al 1987) or for sensible heating of distilled water (Jubraan and Alsaad 1991). Habeebulla et al (1995) used similar measurements for prediction of energy efficiency. Vaishya et al (1985) proposed to calculate K-value of box-type cookers. A model in terms of two figures of merit, proposed by Mullick et al.(1987) has been adopted by Bureau of Indian Standards (Anonymous, BIS, 1992). It enables the prediction of sensible heating time of the water in the cooker pot also. Grupp et al (1991) presented their results on advanced box-type solar cooker in terms of the power output to the pot. Funk and Larson (1998) proposed a model which used a parameter called Cooking Power. This was later on generalized and simplified(Funk 2000). It was proposed to show cooking power in the form of a Standardized Cooking Power(SCP) versus temperature difference (T{sub}w-T{sub}a) graph and a regression equation as a function of (T{sub}w-T{sub}a). The ranges of SCP between experimentally significant temperature difference range (0 to 70°C) were evaluated and were found to be between 0-200W.
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