Investigating the Effect of Different Heat Storage Media on the Thermal Performances of Double Exposure Box-type Solar Cookers

This paper investigates the effect of some heat storage materials on the thermal performances of double exposure box-type solar cookers. Benzoic acid, stearic acid and palm olein oil were used in storing heat in double exposure box-type solar cookers. Using standard methods, some thermal performance parameters were evaluated and compared to that of a control design (no heat storage). The use of benzoic acid increased the average cooking power by 12, 3.6 and 3.4 W for 1, 1.5 and 2 kg of water respectively. Similarly, stearic acid was observed to increase the average cooking power by 1.6 W only for 1 kg of water and palm olein oil was observed to increase the cooking power for only 2 kg of water by 3.2 W. The average first figure of merit were; 0.13, 0.14, 0.12 and 0.11 degrees C m(-2) W-1 for the cooker with benzoic acid, the control cooker, cooker with stearic acid and the cooker with palm olein oil, respectively, while their respective second figure of merit were; 0.45, 0.40, 0.10 and 0.12. Benzoic acid influenced a higher thermal performance, while stearic acid and palm olein oil had a reduction effect. Benzoic acid and palm olein oil had significant effect on the cooking power of the solar cookers, while stearic acid had effect on the first figure of merit.