Technical analysis of an oven with coupled receiver for scheffler solar concentrator tested under cloudy weather conditions

Resumo

Most of the solar collectors experiments are carried out under clear-sky conditions to evaluate the maximum performance of collectors, even though this condition is not critical for some uses, such as cooking. The optical and thermal performance of a solar oven heated by Scheffler concentrator is here analyzed in more adverse weather conditions. The receiver for conversion and heat transfer of the concentrated solar energy is coupled to an oven specially developed for this work. The Scheffler concentrator geometry is a lateral cut angled 43.23° of a paraboloid matrix, and it works in a two-axis tracking system, to always maintain its focal image at the stationary receiver with the progression of the Earth rotation and solar declination movements. A model for distributing the daily radiation over the hours is used to compare the results. The time-constant experimental method is considered. The heating and cooling tests were carried out at the official local time. The maximum temperature achieved by the absorber was 328°C, and the maximum average temperature in the oven was 150°C. The results for heat loss factor were evaluated, and the trends for thermal efficiency and optical efficiency factor were analyzed for the system considered