Department of Mechanical Engineering

Permanent URI for this community

https://ir.unilag.edu.ng/handle/123456789/3475

Browse

Browsing Department of Mechanical Engineering by Author "Adewumi, O.O."

Now showing 1 - 6 of 6
  • Item
    Open Access
    Characterization of a Finned Heat Sink for a Power Inverter
    (Journal of Physics, 2019) Onoroh, F.; Adewumi, O.O.; Ogbonnaya, M.
  • Item
    Open Access
    Computational investigation of thermal behaviors of the automotive radiator operated with water/anti-freezing agent nanofluid based coolant
    (Federal University of Viçosa, Brazil, 2022) Fetuga, I.A.; Olakoyejo, O.T.; Ewim, D.R.E.; Gbegudu, J.K.; Adelaja, A.O.; Adewumi, O.O.
    In this study, a 3D computational fluid dynamics (CFD) study was conducted in ANSYS (FLUENT) to examine the thermal performance of an automotive radiator using conventional and hybrid coolant with a Al2O3 nanoparticles (NPs) . A hybrid mixture of pure water H2O and ethylene glycol (EG) in the volumetric proportion of 50:50, was coupled with Al2O3 nanoparticles with volume fraction of 1% - 4% at different inlet temperatures. The Reynolds number was varied from 4 000 to 8 000. From the numerical results obtained, it was found that an increase in nanoparticle volume fraction led to an increase in heat transfer rate and pressure drop in the automotive radiator. Also, it was found that at a Reynolds number of 8 000, using the hybrid mixture as a base fluid increased the Nusselt number by 55.6% in contrast to pure water. However, further suspension of 4% Vol. Al2O3 nanoparticles into existing hybrid mixture increased the Nusselt number by 70%. Furthermore, it was found that an increase in the inlet temperature of the radiator caused more enhancement in the heat transfer rate. For Re=8 000 4% vol. Al2O3-water nanofluid, the heat transfer rate was enhanced by 54.57% when increasing the inlet temperature from 60oC to 90oC. Therefore, it is recommended that automobile radiators be operated at a high inlet temperature with nanofluid containing a very high concentration of suitable nanoparticles and an anti-freezing agent in an adequate volumetric proportion to achieve better thermal performance.
  • Item
    Open Access
    Constructal heat transfer and fluid flow enhancement optimisation for cylindrical micro-cooling channels with variable cross-section
    (Wiley, 2021) Olakoyejo, O.T.; Adelaja, A.O.; Adewumi, O.O.; Oluwo, A.A.; Bello, S.K.; Adio, S.A.
    This study applies constructal theory to conduct a numerical optimization of three‐dimensional cylindrical microcooling channels with the solid structure subjected to internal heat generation. The cylindrical channels are designed as variable cross‐section configurations that experience conjugate heat transfer and fluid flow, where water is used as the coolant. The research aims to optimize the channel configurations subject to a fixed global solid material volume constraint. The key objectives are to minimize the global thermal resistance and friction factor. The coolant is pushed through the channels by pressure drop represented as Bejan number. The main design parameters are the inlet and outlet diameters at a given porosity. The channel configuration and the structure elemental volume are permitted to change to find the best design parameters that minimized thermal resistance and friction factor, so that the cooling effect is enhanced. An ANSYS FLUENT code is used to obtain the best optimal parameter of the configuration that enhances thermal performance. The influence of Bejan number on optimized inlet and outlet diameters led to minimization of thermal resistance and friction factor and maximization of Nusselt number. The results show distinctive optimal inlet and outlet diameters that enhance the overall performance of the system in the range of 1.018 × 10−2 ≤ (din /L) opt ≤ 1.5381 × 10−2 and 1.0838 × 10−2 ≤ (dout /L)opt ≤ 1.6134 × 10−2, respectively.
  • 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
    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
    Numerical investigation into the thermal performance of a combined heatsink with various microchannel shapes
    (NJTD, 2022) Adewumi, O.O.; Lawal, A.Q.; Olakoyejo, O.T.
    The influence of channel shape on a combined heat sink of three different channel forms is investigated numerically in this work. The channel shapes considered were the trapezoidal, inverse trapezoidal and hexagonal microchannel shapes. The goal of this study was to compare and identify the combined microchannel shape that performed best under conditions of high uniform heat flux. The thermal performance of the combined heat sink was assessed using two criteria: lowest maximum temperature and lowest temperature elevation on the bottom of the combined heat sink where heat is applied. The uniform heat flux applied to the bottom of the combined heat sink was elevated from 100 W/〖cm〗^2to 1000 W/〖cm〗^2. For the maximum heat flux of 1000 W/〖cm〗^2and lowest pressure drop of 10kPa considered, in terms of temperature elevation on the bottom of the heat sink where heat is applied, the trapezoidal combined microchannel heat sink outperformed other channel shapes. When the minimized overall maximum temperature is considered, the hexagonal combined microchannel heat sink was the best combined heat sink.