Thermal analysis of paraboloid dish type solar cooker

Abstract

This study presents thermal performance analysis of paraboloid dish type solar cooker under steady and unsteady state conditions. The performance is analyzed under two conditions: firstly steady state operation of cooker subjected to radiation and convection losses from vertical cylindrical surface & top cover of the cooker and secondly unsteady state operation of cooker associated with mass transfer from cooker to the surrounding when heat is supplied at a constant rate to the cooker after saturation pressure is reached. Under steady state condition, predicted value of average thermal efficiency of cooker is 54%, first and second figures of merit are respectively 1.7 and 3.4, time taken to raise the temperature to 95°c is 24 minutes and time for boiling is 26 minutes. The difference in predicted and experimental results can be attributed to unaccounted losses from the cooker surface and operational error. In the second case, energy leaves the cooker with steam at a rate of 0.91 kW, accompanied by heat losses by convection and radiation from the outer surface of the cooker.