scholarly works
Permanent URI for this collectionhttps://repository.ui.edu.ng/handle/123456789/477
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Item Numerical and experimental investigation on performance of convex-cut baffles in shell-and tube heat exchanger(2020) Petinrin, M. O.; Dare, A. A.In this study, comparative performance of single-segmental baffle and a newly developed baffle –convex-cut in shell-and-tube heat exchanger were both numerically and experimentally investigated. For the numerical analysis, three working fluids (engine oil, water and air) were successively utilised on the shell-side of heat exchangers with 30, 35, 40 and 45% convex-cut (CeC_STHE) and 25% segmental (SS_STHE) baffles, and the resulting models were solved in COMSOL Multiphysics. Experiments were carried out on 30% CeC_STHE and SS_STHE exclusively running on water. The data obtained were used to determine the weighted shell-side heat transfer coefficient and weighted performance factor of each heat exchanger. Hence, the results for all the ranges of Reynolds number indicate that the shell-side heat transfer coefficients of all the CeC_STHEs are lower than that of SS_STHE except for the 30% CeC_STHE. However, the SS_STHE showed greater pressure drop than the CeC_STHEs. The choice of working fluid had more influenced on the weighted shell-side heat transfer coefficient CeC_STHE. Moreover, the weighted performance factors of the CeC_STHEs indicated positive values. Thus, 30% CeC_STHE demonstrated a better performance while the 45% had the lowest performance.Item Numerical investigation of the concave-cut baffles effect in shell-and-tube heat exchanger(2019) Petinrin, M. O.; Dare, A. A.In this paper, the performance of shell-and-tube heat exchangers with single-segmental baffle and varying configurations of concave-cut baffles (10, 15 and 20 %) was investigated. The study was carried out for a heat exchanger having either engine oil, water and air as shell-side fluid. For each configuration of the baffles, the results of both the k-ε and RNG k-ε turbulent models were in very close agreement. The heat exchangers with concavecut baffles had higher pressure drops and lower performance factors than that of single-segmental baffle at the same range of mass flow rates for all fluid cases. Also, the concave-cut baffle heat exchangers had lower shell-side heat transfer coefficients at the same pressure drop against that of single-segmental baffles. Thus, the use of concave-cut baffles did not exhibit desirable performance in heat exchanger as compared with the segmental baffles.Item Entropy generation minimisation of shell-and-tube heat exchanger in crude oil preheat train using firefly algorithm(2018) Petinrin, M. O.; Bello-Ochende, T.; Dare, A. A.; Oyewola, O. M.This paper presents the entropy generation analysis and optimisation of typical shell-and-tube heat exchanger in the preheat train of crude oil distillation unit. The implication of entropy minimisation on energy consumption associated with design of heat exchanger was studied. The developed optimisation model was solved by employing the firefly algorithm. A number of constraints were applied with thirteen decision variables. The ε-NTU method and Delaware method were used for the heat exchanger design. Four cases were considered for each of two selected samples and were categorised under two studies. Total entropy generation rates for all the four cases considered were almost the same, and the dominant irreversibility distribution is by heat transfer. However, the sharp decrease in entropy generation due to fluid friction caused a great reduction in pumping power in the range of 51.4–82.1% and 54.8–92.2% for the two studies, respectively. The results of sensitivity study on the decision variables showed sharp reduction in entropy generation rate and increased pumping power as the mass flow rate increases for all the variables. Also, the choices of the tube diameter and tube number had greater impact on the changes in entropy generation rate and pumping power.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 Numerical modelling of thermal distribution control in a furnace(2018) Petinrin, M. O.; Ajide, O. O.; Dare, A. A.; Oyewola, O. M.; Ismail, O. S.Application of control to heat treatment processes helps to achieve the desired mechanical properties of materials but improper controller design is a major problem causing short lifespan of components of locally made furnaces. In this study, the numerical control of the temperature distribution within a furnace cavity was carried out using COMSOL Multiphysics and Simulink. Six sensor points within the furnace cavity (with and without specimen) were selected and each point was consecutively used to observe the time response of the sensor to the desired temperature. The results from the time response analysis indicated uneven temperature distribution within the furnace with points located at the corners of the furnace recording the highest temperature rise while points at the centre of the furnace or within the specimen having the lowest temperature. Thus, the best position for a sensor is at any corner of the furnace to protect the components of the furnace from damage.Item Numerical modelling of effect of baffle orientation offset on shell-and-tube heat exchanger performance(2018-02) Petinrin, M. O.; Dare, A. A.The performance of a shell-and-tube heat exchanger (STHE) is largely dependent on the type, orientation and offset arrangement of the baffles employed. In this paper, the thermal-hydraulic characteristics of STHEs with 90°, 120° and 180° offset arrangements of baffles were studied numerically. The study was performed on 19-tube and 31-tube heat exchangers, and also for three shell-side working fluids: air, water and engine oil. The numerical analyses were carried out using the k-ε model with imposed realizability constraint, and were solved with COMSOL Multiphysics. The STHE with 180° had higher pressure drop than other STHEs for all the ranges of mass flow rate. STHE with 120° showed better performance for shell-side heat transfer coefficient at the same pressure drop while STHE with 90° had much higher performance factor at the same mass flow rate. It is concluded that baffle offset arrangements significantly affected the shell and tube heat exchanger performance.Item Performance of shell and tube heat exchangers with varying tube layouts(2016) Petinrin, M. O.; Dare, A. A.Shell and tube heat exchangers (STHEs) are the most common type of heat exchangers and are applicable for wide range of operating temperatures and pressures. Numerical analyses on thermalhydraulic performance of three sets of shell and tube heat exchangers (STHEs) with different geometrical tube layout patterns variations namely; triangular (30º, STHE_T), rotated triangular (60º, STHE_RT) and the combined (STHE_C) patterns were carried out in this study. The results from solving the governing continuity, momentum and energy equations showed that bulk of the heat transfer and pressure drop occur during the cross-flow of shell-fluid through the tube bundles. Evaluation of the performances of the heat exchangers showed that the STHE_T is more desirable followed by the STHE_C as they exhibit higher heat transfer coefficient than the STHE_RT for the same pressure drop in the shell-side.Item 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.Item Modelling of natural convection along isothermal plates and in channels using diffusion velocity method(2010) Dare, A. A.; Petinrin, M. O.The diffusion velocity method (DVM), a version of vortex element method (VEM), was used to model the steady state, laminar natural convection flows along isothermal vertical plates and in isothermal vertical channels. For each case, numerical models were developed using DVM from the vorticity transport equation and the energy equation. This study shows that the diffusion velocity method is a viable numerical tool at modelling not only fluid flow problems but also the heat transfer problems.Item Numerical simulation of microchannel(2022) Adebayo, J. K.; Oyedepo, S. O.; Petinrin, M. O.; Dare, A. A.; Nwaokocha, C. N.; Layeni, A. T.; Fayomi, O. S. I.; Dirisu, J. O.; Kilanko, O.This study numerically investigates a double pipe heat exchanger with triangle and rectangle rib. The simulation is performed using ANSYS package, considering turbulent flow and k-e turbulence model. The working fluid is water in both tube and annulus and the flow arrangement is counter flow. The results show that, the heat transfer of triangle rib and rectangle rib are higher than that of normal DPHE and as the Reynolds number is increasing heat transfer, coefficient of heat transfers and Nusselt number are also increasing. Triangle rib has thermal performance factor of 0.9786 at Re of 40000 and rectangle rib has 1.0290 at Re of 30000. furthermore, total heat transfer of DPHE with triangle rib is 33% better than normal DPHE at Re of 40000 and that of rectangle rib is 45% better at Re of 40000