Thermodynamic Analysis of an Evacuated Tube Solar Cooker under Different Operating Conditions

In this study, the performance of an evacuated tube solar cooker with a steel tank is investigated from the energy and exergy viewpoints. For this purpose, the solar cooker is initially examined at no-load condition. Moreover, the solar cooker is utilized to boil water at solar radiation intensities of 700 W/m2 and 900 W/m2. The investigated parameters in this research are fluid temperature, the outer surface temperature of the evacuated tube, the rate of the absorbed thermal energy by water, the rate of the exergy change of water, and the energy and exergy efficiencies of the solar cooker. The results indicate that at no-load condition, the air temperature in the steel tank and the temperature of the outer surface of the evacuated tube increase by 214.2 ºC and 15.5 ºC after 1 hour, respectively. In addition, the time required to boil 800 gr of water at solar radiation intensity of 900 W/m2 is 1 hour and 25 min. Based on the results, the average energy and exergy efficiencies of the evacuated tube solar cooker at solar radiation intensity of 900 W/m2 are 16.16% and 1.57%, respectively. Rising the solar radiation intensity from 700 W/m2 to 900 W/m2 enhances the exergy efficiency of the solar cooker by 0.78%.