Department of Mechanical Engineering

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Browsing Department of Mechanical Engineering by Author "A. T. Abdulrahim"

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    APPLICATION OF STEARIC ACID FOR SOLAR THERMAL ENERGY STORAGE IN A DOUBLE COMPARTMENT SOLAR BOX COOKER
    (2019-06) M. B. Maina; S. Shodiya; A. T. Abdulrahim
    Energy storage in some form is the need of the hour to even out the mismatch between energy supply and demand. Thermal Energy Storage (TES) system employing a phase change material (PCM) has been widely considered as an effective way to store and retrieve energy due to its high heat storage capacity at almost constant temperature during the phase change. In this work, an energy storage system was designed to study the heat transfer characteristics of stearic acid (as a phase change material in a double compartment solar box cooker (DCSBC) fabricated using wooden materials with high thermal energy storage system. In order to analyze the various characteristics of the PCM, the Bureau of Indian Standards (BIS) was used throughout the experiment. Investigations were performed to determine the first and second figure of merits (F1 and F2) of compartments 1 and 2 (C1 and C2) simultaneously. The results for F1 were found to be (C1= 0.14 and C2= 0.15) and F2 were (C1=0.47 and C2= 0.4) while the overall thermal efficiency of the cooker after water boiling test for C1 with 2.5kg and C2 with 3kg of water were deduced to be 77% for C1 and 92% for C2 after six hours of the load test, showing considerable temperature increase and extension of heat retention making possible to cook the dinner and even breakfast the next day.
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    Characterization and Generation of Municipal Solid Waste in North Central Nigeria
    (International Journal of Modern Engineering Research (IJMER), 2012-10) M. B. Oumarou; M. Dauda; A. T. Abdulrahim; A. B. Abubakar
    The study focused on the characterization and generation of municipal solid waste in the north central part of Nigeria. Daily samples were collected and interpreted using Microsoft Excel for quantification purposes while the characterization samples were collected during the months of February, March and April and during the raining season in August. The refuse physical characteristics were then evaluated by sifting through the waste and separate it into its various physical major components. They were analyzed for proximate and ultimate composition using ASTM standards. Average moisture contents were found to vary from 26.743 to 32.593. Wood, paper, plastic and leaves were found in varying proportions and an average waste generation of 1. 23 kg per person per day was found. Energy recovery is possible with an addition of supplementary fuel as sugar cane straw, weeds. The knowledge of the refuse CV alone is not enough to conclude whether the refuse will burn or not. Its moisture content is also an essential parameter.
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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.
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    THERMAL AND MECHANICAL PROPERTIES OF CLAY AND DROP-OFF OF CEIBA PENTANDRA (KAPOK) PLANT WOOL MIXTURE
    (2020-06) A. T. Abdulrahim; S. Abdulkareem; S. A. Abdulraheem; W. J. Mohammed
    This study is aimed at the investigation of the effects of the addition of clay to drop-off of Ceiba pentandra (Kapok) plant wool on the thermal and mechanical properties of the materials produced. Because of the considerable increase in the use of insulations in many heat devices, process and systems, and dependence on imported insulations, the need to process natural fibre insulations to form rigid or semi-rigid material using appropriate and sustainable binding material cannot be over emphasized. For this study, Kapok wool and clay mixture were investigated. Five samples were prepared: Sample A was 100% Kapok wool while samples B, C, D, and E were mixture of Kapok wool and Clay in water with varying percentage of clay quantities (Kapok to Clay ratio; B 2:1, C 2:1.5, D 2:2.5, E 2:3.5). The samples were prepared into cylindrical shapes, compressed and dried. The Thermal conductivity meter on Armfield Heat transfer equipment was used to find the thermal conductivity of each sample, while the thermal diffusivity and thermal resistivity of samples were determined using appropriate formula. Universal Testing Machine (Model: FS 50AT) was used to determine the stress at Yield and Young Modulus of elasticity for samples B, C, D, and E. Results show that the density of sample increases with increase in clay content. Thermal conductivities of the samples after the addition of clay ranges between 0.027 (W/mK) and 0.013 (W/mK). Reversed was the case for Thermal Resistivity, the value of thermal resistivity first decreases with addition of clay content (sample B) and then started increasing with increased clay content in the samples, and the values range from 37.037 to 76.923mKW-1. Thermal diffusivity of sample decreases from 1.2762 x10-3 m2 /s to 0.2810 x10-3 m2 /s with increasing clay content. Results also show that the Stress at Yield of samples range from 0.012 N/mm2 to 0.022 N/mm2 while the Young Modulus of elasticity range from 0.113 N/mm2 to 0.222 N/mm2 . Kapok wool – Clay combination of ratio 2:3.5 (Sample E) have the highest value of thermal resistivity and lowest thermal diffusivity, though with high density, which suggests it to be the best among samples in the study for insulation purposes. The products are recommended for use as insulations of thermal storage for medium temperature applications