Thermal Performance of a Reflector Based Solar Box Cooker Implemented in Ile-Ife, Nigeria

Abstract

Different categories of solar cooker ranging from concentrator types, solar ovens, box type cookers with or without reflectors and indirect solar cookers have been designed and tested in Nigeria. The uses of different designs of solar cookers have not become acceptable in the rural areas due to number of reasons. It is either they are too expensive for individual family to afford or they are yet to be practically known. In view of these shortcomings, this paper presents thermal performance of low cost reflectors based solar box cooker implemented in Ile-Ife, Nigeria. The cooker was constructed with locally available materials. The thermal performance of the cooker in terms of figures of merits and cooker efficiency was evaluated based on Indian Standard (IS 13429:2000). Results of field evaluation show maximum insolation of 520 W/m2 at 2.00 pm and minimum of 246 W/m2 at 11.00 am. The average solar radiation and ambient temperature observed during the test periods were 403 W/m2 and 40°C respectively. The water temperature values between 60 and 67°C were observed at insolation values between 398 and 520 W/m2. These occur between the hour of 1:20 pm and 4:00 pm with the highest water temperature of 67°C at 3.00 pm. The performance of the cooker in terms of first figure of merit, second figure of merit and thermal efficiency show that the cooker compare favourably well with international standard. The cooker has a better heat retention capacity when compared with others found in the literature. The experimental results obtained for thermal performance of the cooker demonstrated its suitability for cooking even during fluctuating weather conditions.