Mechanical Engineering-Scholarly Publications

Permanent URI for this collection

https://ir.unilag.edu.ng/handle/123456789/3486

Browse

Recent Submissions

Now showing 1 - 5 of 72
  • Item
    Open Access
    Experimental and numerical determination of the heat transfer coefficient of fiber-glass/talc filled epoxy
    (APWEN Journal of Engineering, Science and Technology, 2021-12) Udebuani, O.P.; Onitiri, M.A.; Adewumi, O.O.
    This research was conducted to examine the experimental and numerical heat transfer coefficient of fiber-glass/talc-filled epoxy composites. And then, the numerical results were validated with the experimental results. Fiber-glass/talc-filled epoxy composites were prepared with different mixing ratios, cured at room temperature for 24 hours and then post-cured at varying temperatures (50˚C, 75˚C, 100˚C, 125˚C, and 150˚C) while keeping the curing time constant. Models of the composites were generated in ANSYS using the thermal properties of the composites with different mixing ratios and curing time, the properties of the heater were also inputted and the air was the convective fluid. The heat was applied to the composites and the inner and outer wall temperatures were taken and used to determine the heat transfer coefficient of the composites. From the results obtained numerically, it was observed that increase in post-curing temperature led to an increase in composites with higher talc particle size (106μm) while the heat transfer coefficient of the composites with lower talc particle size (75μm) exhibited a lower heat transfer coefficient. In order to validate the numerical model, an experiment of composites with a lower heat transfer coefficient than epoxy post-cured at 100˚C was carried out following all the steps taken in the numerical simulation, and the results were compared.
  • Item
    Open Access
    Fabrication of extrudate filament from waste polyethylene terephthalate (PET) plastics for 3D printers
    (FUOYE Journal of Engineering and Technology, 2021-06) Eboh, F.C.; Osideko, O.O.; Onitiri, M.A.
    The use of 3D printers for manufacturing processes comes with the challenge of filament replacement for subsequent processes. This aforementioned including the environmental problems posed by plastics wastes formed the basis for the current work which is focused on design and construction of a simple single extruder for the production of filaments from waste polyethylene terephthalate (PET) plastics for rapid prototyping machines and 3D printers. Three Band heaters were used to melt the PET plastics and a screw was used to move the melted PET plastics longitudinally along the barrel. The screw is consisted of three zones namely feed zone, compression zone and metering zone. The temperature of the band heaters is controlled by a Digital temperature controller. This paper describes the design, fabrication and testing of a filament extruder. A 2mm die was used to extrude the filament to1.75 mm. The performance of the system was quantified through relevant tests and the findings reported. When the barrel and die assembly are at 200°C, melting begins to occur and at 230°C, the extrudate begins to appear at the metering zone. The energy efficiency of the system was found out to be 75.2%.
  • Item
    Open Access
    Numerical and experimental investigations of the performance of fiber-glass/talc epoxy composites insulated water heater
    (Bayero Journal of Engineering and Technology, 2021-01) Adewumi, O.O.; Onitiri, M.A.; Olusanya, A.H.; Oluwadusin, A.T.
    The determination the best epoxy composite reinforced with talc and fiber glass that can be used for insulation in hot water storage applications is investigated in this study. Numerical simulations, using a computational fluid dynamics software, were carried out on various percentage mixtures of epoxy composite reinforced with talc and fiber glass cured at different temperatures and their performance as insulators for water heating tank was analyzed and compared with other materials. Thereafter, experimental tests were carried out on the chosen composite that is fabricated and results obtained compared with those obtained numerically. Results obtained showed that the epoxy-based composite cured at 75ºC is the best insulator for hot water storage. Also, when the interface maximum temperature at the inner tank wall/composite for all the 40 different fiber-glass/talc filled epoxy composites were compared with two common mate-rials - fiber-glass and epoxy, 16 of these composites possessed better heat storage capabilities than fiber glass and epoxy. This shows that fiber-glass/talc epoxy composites are good replacements for existing materials used for insula-tion in hot water storage applications.
  • Item
    Open Access
    Effect of iron ore tailings particle sizes on the thermal properties of epoxy and polypropylene matrix composites
    (FUOYE Journal of Engineering and Technology, 2020-09) Oyebode, J.O.; Mbagwu, V.N.; Onitiri, M.A.
    Thermal properties of materials such as plastic matrix composite is one of the important parameters for determining their behaviour and relevant applications. This present work focuses on determining the thermal behaviour of epoxy and polypropylene (PP) matrix composite reinforced with iron ore tailings (IOT) particulates of sizes 150 μm, 212 μm and 300 μm at various loadings of 5%, 10%, 15%, 20%, 25%, and 30%. The thermal behaviour of the developed composites was investigated experimentally using a KD2 pro thermal analyser. The results obtained from the experiment showed that increasing filler loading in epoxy leads to increased specific heat capacity and thermal resistivity. The maximum values recorded for the thermal resistivity and specific heat capacity were 0. 592°C.m/W and 2.352 J/kgK respectively. Thermal conductivity and thermal diffusivity of values 0.168W/mK and 0.089 mm²/s respectively were the lowest obtained for the epoxy matrix composite. It was also observed that addition of IOT in PP had significant effect on the thermal properties of the PP composite. Thermal conductivity and thermal diffusivity were found to increase with increased particle loading compared to the pure PP sample; the highest value being 2.235 W/mK and 5.51 mm²/s for thermal conductivity and thermal diffusivity respectively while low values of 0.05 Cm/W and 0.371 J/kgK was recorded for thermal resistivity and specific heat capacity. The presence of iron ore tailings reduces the thermal conductivity and diffusivity in epoxy but increases the conductivity and diffusivity in polypropylene.
  • Item
    Open Access
    Thermal conductivity and impact properties of iron ore tailings filled epoxy composites
    (Nigerian Journal of Technology, 2019-07) Onitiri, M.A.; Oladosu, S.A.; Badmos, A.Y.
    Iron ore tailings which is the waste material derived from the beneficiation of iron ore was dispersed in epoxy as micro scale particle fillers. The effect of particle size and particle loading on the thermal conductivity and impact properties of the composites were then investigated experimentally. A comparison of the experimental results for the former to results obtained from existing theoretical models was also done. It was discovered that the impact resistance increased with increasing volume content of iron ore tailings from 20 vol. % with a maximum toughness of 0.098 kJm-2 recorded for composite with 300 μm at 30 vol. %. Thermal conductivity of epoxy improved with decreasing particle size while the Maxwell, Lewis and Nelson and parallel models gave reasonable predictions for epoxy filled with 212 μm at 10 vol. % and 20 vol. % contents; with least variations of 0.18 % and 1.26 %, respectively.