FACULTY OF TECHNOLOGY
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Item Numerical study of the effect of changing tube pitches on heat and flow characteristics from tube bundles in cross flow(2019) Petinrin, M. O.; Towoju, O. A.; Ajiboye, S. A.; Zebulun, O. E.Tube bundles are found in various heat transfer equipment for thermal energy transfer between fluids. However, the inter-spatial arrangement of the tubes of any tube bundle is a determining factor for its thermal and hydraulic performance. In this paper, the effect of varying the transverse and longitudinal pitches downstream staggered circular tube bundle on the heat transfer and flow characteristic was numerically analyzed. Seven variations of tube arrangements were studied by changing the tube pitches within a Reynolds number range of 7 381 to 22 214. The analyses were carried out using the k-ε equation model imposed with the realizability constraint and were solved with finite volume CFD code, COMSOL Multiphysics. The results obtained were found to be in good agreement with existing correlations. The tube bundles with decreasing pitches demonstrated better heat transfer performance while those with increasing pitches exhibited a lower friction factor. Thus, the best thermal-hydraulic performance was obtained from increasing pitch arrangements.Item Numerical investigation of shell-and-tube heat exchanger with parabolic segmental baffle cut(2019-01) Ikpotokin, I.; Uguru-Okorie, D. C.; Osueke, C. O.; Dare, A. A.; Petinrin, M. O.An investigation was carried out on the effect of the use of a parabolic baffle at different baffle cuts on the performance of shell and tube heat exchangers. The numerical study was performed on a personal computer with 12 GB RAM and Intel® Core™ i7 2.50GHz CPU using a CFD software Comsol Multiphysics. The modeled heat exchanger had 37 tubes, shell internal diameter of 200 mm, 6 baffles with baffle spacing of 100 mm. The results from the effect of mass flow rate and baffle cut on heat transfer rate and pressure drop in the shell side of the heat exchanger were compared with the circular segmental baffle cut of 25% and that of the parabolic baffle cut of 25 and 30% of the inner shell diameter. At 25% of the shell diameter baffle cut, the parabolic cut had an improved heat transfer rate compared to that with the circular segmental baffle cut with a drawback of higher pressure drop. As the parabolic baffle cuts increased, there was a decrease in heat transfer rates and pressure drops at the various mass flow rates considered. At 30% of shell diameter cut, the performance of the parabolic segmental baffle cut gave results similar to the circular segmental baffle cut at 25% of the inner shell diameter. The investigation showed that for a parabolic baffle cut, 30% of the shell diameter is recommended for optimum performance.Item Effect of viscous dissipation term on a fluid between two moving parallel plates(2018-08) Petinrin, M. O.; Adegbola, A. A.The fully developed laminar heat transfer of a Newtonian fluid flowing between two parallel plates where the bottom plate is fixed and the top plate is moving in an axial direction at constant speed was analyzed taking into account the iscous dissipation of the flowing fluid. Applying the velocity profile obtained for the plane Coutte-Poiseuille laminar flow, the energy equation with the viscous dissipation term was exactly solved for the boundary conditions of constant wall heat flux at one wall with the other insulated. Special attention is given to the shear produced by the movable top plate over and above the viscous dissipation due to internal fluid friction. The reason behind the behaviour exhibits by the temperature profile obtained at different velocities can be attributed to the effect of viscous dissipation coming into play due to the shear stress within the fluid layer induced by the movement of the upper plateItem Forced convection on isothermal plates and channels using diffusion velocity(2010-06) Petinrin, M. O.; Dare, A. A.; Oke, S. A.In many industrial applications, such as electronic systems, performance failure and breakdown usually occur due to poor thermal management, which could be adequately controlled through a proper understanding and management of the forced convection system and use of the vortex element method. The main contribution of this paper is that it shows how the vortex element method is capable of producing results similar to those reported in literature. The paper utilised vortex element method to model familiar problems in heat transfer, which is laminar flow over isothermal flat plate and isothermal two parallel-plate channels. Numerical models were developed using diffusion velocity method, a version of vortex element method, from vorticity transport equation and the energy equation for each of the cases. The velocity and temperature distributions, obtained for both plates and channels, were utilised to calculate Nusselt numbers with Reynolds numbers in the range of 20 to 120. The logarithmic plot of Nusselt number versus Reynolds number for forced convection on single horizontal plates yielded a slope of 0.46 and an intercept of -0.29 while that for forced convection in horizontal channels had a slope of 0.87 and an intercept of -0.88. The results obtained in this work show the diffusion velocity method to be a viable numerical tool for modelling fluid flow problems and also heat transfer problems.