THERMAL PERFORMANCE OF A PROTOTYPE QUONSET-SHAPED SOLAR COOKER

The aim of this work is studied the thermal performance of a local made prototype Quonset-shaped solar cooker provided with an transparent fiberglass sheets under the local climatic conditions of Zagazig city, Egypt (Lat. 30° 35 N ; Lon. 31° 31 E). The Quonset geometric shape of the cooker cover was chosen to obtain a large enclosure volume to increase the accumulated solar heat inside the cooking compartment. The cooker was divided into two equal compartments with aperture area 0.12 m2 and provided with internal solar reflective films. The Thermal performance of cooker was evaluated using the conventional absorber plate (CAP) and black stones pebbles bed (BSB) with different water loads and under the passive and active (the integration of the cooker with a solar flat-plate collector and PV system (modes with taking into consideration the first figure of merit, utilizable efficiency, specific and characteristic boiling times.  The results revealed that, the solar cooker with CAP achieved stagnation temperature of about 10% more than the BSB cooker with delay 40 min and first figure of merit of 0.12 °C.m2/W, whereas the CAP was 0.11°C.m2/W. The active solar cooker with CAP achieved the highest utilizable efficiency of 36.6% with an increment by about 26.5% than the passive one at the maximum water load of 1.50 kg, while the utilizable efficiency of the solar cooker with BSB was 22.52 and 26.9% for the passive and active modes, respectively. Hence, It is recommended to use the active solar cooker with CAP to achieve a good thermal performance because this cooker with aperture area of 1 m2 can boil 1 kg of water in about 18 min at utilizable efficiency of 25% which reduced the boiling time by about 21.74%, whereas the passive cooker with BSB is useful when the evening cooking is concerned and it is not recommended to use this cooker in active mode