Experimental Investigation of Double Exposure Solar Cooker with an Asymmetric Compound Parabolic Concentrator

This work provides the experimental test results and findings of solar cooker developed in Bahirdar. The cooker is double exposure type consisting of plane reflectors being fixed on top glazing and an asymmetric compound parabolic concentrator fixed on the side wall. It has a box casing with an aspect ratio of 2.66 and overall dimension of(920\, {\text{mm}} \times 343\,{\text{mm}} \times 400\,{\text{mm}}). Stagnation tests were conducted on the double exposure and conventional solar box cooker. From the test maximum absorber plate temperature of 145 ℃ for the double exposure and 122 ℃ for the conventional cooker have been achieved at 12: 30 PM and 12:40 PM respectively. The respective first figure of merit values were found to be 0.123 and 0.088, the former satisfying minimum requirement as per BIS. Water or load test conducted indicates as it has taken 2 h and 30 min for 2 L of water to boil in the double exposure solar cooker while in conventional cooker water doesn’t reach its boiling point, being heated to a maximum temperature of 88 ℃. For the food cooking, 1 kg of rice distributed in two pots was cooked in 1 h and 35 min, starting from 10:00 AM. 1 kg of bean was cooked in 2 h and 45 min. The double exposure cooker is therefore able to cook hard meals like bean and soft meals like rice and spaghetti two and four times per day respectively. This food cooking result has good implication that if intensive work is done, solar cookers can be disseminated into and used by the society.