Experimental investigation of a box-type solar cooker incorporated with Fresnel lens magnifier.

The study was conducted to evaluate the thermal performance of a box-type solar cooker (BTSC) by implementing two Fresnel lens magnifiers (FLMG) which concentrate the solar irradiance on to the cooker surface. A comparison in thermal performance was done in the presence and absence of the Fresnel lens magnifier. Three main tests, namely, stagnation test, load test, and cooking power test were conducted for determining the performance. It was seen that the first and second figure of merit increased from 0.11 to 0.12ᵒCm2/W and 0.43 to 0.45 respectively in the presence of the Fresnel lens magnifier. A linear regression analysis of the plotted points was used to develop a relationship between standardized cooking power and temperature difference and the cooking power for a temperature difference of 50ᵒC was calculated. The cooking power enhanced from 43.83 W to 46.87 W at the temperature difference of 50ᵒC by the usage of the magnifier. The average value of transmittance for the magnifier was 72.26% for the solar energy spectrum. The geometrical concentration ratio was increased by 48.7% by incorporating the Fresnel lens magnifier. The average value of energy efficiency of the solar cooker was calculated and was found to increase from 29.6% to 32.04% by adding the Fresnel lens magnifier. [ABSTRACT FROM AUTHOR]