Browsing by Author "G. M. Ngala"

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    Design, Fabrication and Performance Evaluation of Solar Brick Oven
    (2016-01-01) M. B. Maina; G. M. Ngala; A. T. Abdulrahim
    -Bread baking in Maiduguri and environs (north eastern Nigeria) is mainly done in ovens that are fuelled by charcoal sourced from fuel-wood; this process releases harmful greenhouse gasses to the atmosphere with known negative effects on the environment. The demand for fuelwood as energy source by bakeries and household users is increasing while the resource is becoming scarce and costly when available. These require immediate attention by providing alternative sources that are environmentally safe, less costly and accessible locally, so that overdependence on fuel-wood is greatly reduced. A potentially cost effective alternative energy source that is locally available is the solar energy. Three materials (glass, Perspex and aluminum) were used as window/screen materials for the oven, onto which a parabolic solar collector was focused. All the three materials achieved baking bread at different temperatures and time, Glass oven baked at 90oC screen temperature and 120OC oven temperature in 3hours, Perspex oven baked at 150oC screen temperature and 130OC oven temperature in 3 ½ hours and aluminum oven baked at 130oC screen temperature and 150OC oven temperature in 2hours thirty minutes with solar insolation of 850 w/m2 on the test day. Glass and Perspex sustained defect at different temperatures and exposure time. It was observed that aluminum screened solar oven produced bread with oven performance efficiency of 16% while glass screened oven produced bread at 63% efficiency and Perspex screened oven produced bread at 51% efficiency. Temperature profiles within and outside the oven were analyzed (with and without load). Analysis of the experimental results showed that solar radiation, ambient temperature and wind velocity with respect to the screening materials were the most influential factors.
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    PERFORMANCE EVALUATION OF SOLAR OVEN USING KAPOK WOOL AS INSULATION MATERIAL
    (2020-12) A. T. Abdulrahim; S. Abdulkareem; M. Haruna; A. S. Abdulraheem; F. A. Oluwole; G. M. Ngala; U. A. Mukhtar
    Solar ovens are among common devices which utilize insulation materials because of their ability to retards heat transfer by acting as barriers in the path of heat flow. Previous solar box cookers have used cotton, saw dust, and fibre-glass as insulation materials but none has used Kapok wool despite its potential. This study is aimed at the performance evaluation of solar oven using Kapok wool as the insulation material. The solar box oven designed is of the size 59 x 56 x 36cm dimensions made of plywood, with an aperture area of 3304cm2 double glass cover and an oven’s floor area of 1225cm2 made of aluminum. Kapok wool was used to line the oven’s walls and floor serving as insulator. The solar box oven was tested at the University of Maiduguri, Borno State, Nigeria. It was tested without load to determine its stagnation temperature and to check its endurance under stagnation conditions. Similarly, a water boiling test was conducted to cook rice and beans. The results show that maximum stagnation temperature was 165.1°C and maximum overall daily thermal efficiency of 19.44% was achieved on a clear day test without reflector. The field test of the solar oven demonstrated its ability to cook rice and beans well with 1 kg of rice cooked under 2 hours, while 1 kg of beans was cooked under 1 hour 45 minutes on the same day. This performance demonstrated the suitability of Kapok wool as insulation material for solar ovens.