A new collector of solar radiant energy—Theory and experimental verification

Abstract

An effective quality control is essential for a large-scale dissemination of solar thermal technologies on the products being offered by the industry to the end users. For this, there is a need to establish test procedures and methodologies for producing performance characteristic parameters, which could provide an equitable basis for comparison of performances of these products. At present, paraboloid concentrator type solar cooker technology is moving towards the phase of commercialization in India. For the thermal performance evaluation of paraboloid concentrator type solar cooker, Mullick et al. (1991) developed a test procedure that essentially recommends determination of optical efficiency factor (F′ηo) and heat loss factor (F′UL) based on heating and cooling tests. Further a test method has been proposed by Funk (2000) for testing of all kind of solar cookers that characterizes the performance of solar cooker by two parameters, namely, adjusted cooking power (Pa) and overall heat loss coefficient (UL) as obtained from heating test. These are the only test methods available for testing of paraboloid concentrator type solar cooker.The present communication analyzes the effect of instrumentation, on the values of F′ηo, F′UL, Pa and UL, which is supported by a large number of outdoor tests conducted on a paraboloid concentrator type solar cooker under heating and cooling test conditions. The role of individual associated parameters on F′ηo, F′UL, Pa and UL has been analyzed along with the estimation of overall error in these values due to the error in the determination of associated parameters. Though the maximum attainable accuracy in determining F′UL varies from 1.15% to 0.65% (for loads of 1.0 to 8.0 kg), the associated error in the determination of F′ηo is quite high viz. 5.13% to 5.04% for the same load conditions. Similarly, the maximum attainable accuracy in the determination of standardized cooking power has been observed from 4.98% to 5.02% under the load conditions from 1.0 to 8.0 kg.