Adekunle AdelajaUniversity of Lagos · Department of Mechanical Engineering
Adekunle Adelaja
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51
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379
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Introduction
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Publications
Publications (51)
This study investigates the effect of tube layout configurations on the hydraulic-thermal performance of shell-and-tube heat exchangers (STHXs) as waste heat recovery systems. The STHXs are triangular (30°, STHX-T), rotated triangular (60°, STHX-RT), and combined (STHX-C). Water at a temperature of 10 °C was circulated through a bundle of tubes inl...
This paper numerically investigates the effects of hybridization of water-based copper-alumina nanofluid on the thermal performance, pressure drop, and the figure of merit (FOM) inside a three-dimensional microchannel heat sink. The heat sink comprises a copper block with the top covered by a polycarbonate plastic (Lexan) to form a closed microchan...
This study investigates numerically the 2D laminar natural convection in a Saltbox roof type geometry under summer climate conditions as obtained in Africa, particularly Nigeria using ANSYS FLUENT to model the boundary conditions. The effects of Rayleigh number (Ra) within the range of 103-107 and pitch angles (top and base) on heat transfer, the f...
This research work scrutinizes thermal analysis of nanofluidic flow through MWCNTs subjected to perfectly and imperfectly bond wall conditions. Employing continuity of flow, Navier stokes equation (NS), energy equation for fluid and energy equation for MWCNTs, the thermal-fluidic models in partial differential forms are developed. Thereafter, the e...
This paper explores the nonlinear partial differential equations (PDEs) for transverse and longitudinal vibrations of slightly curved fluid-conveying embedded branched nanotubes operating in a magnetic environment. Using Bernoulli–Euler, Nonlocal and Hamilton theories, equations of motion governing the vibrations of the nanotubes are developed. The...
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...
In the current study, the influence of inclination angle, temperature difference, mass velocity, and vapour quality is investigated on the entropy generation rate in an inclined enhanced tube during the flow condensation of R134a. The enhanced tube is a microfinned tube with a helix angle of 14o. The experiments are carried out at a saturation temp...
In this study, the numerical analysis of conjugate heat transfer of laminar flow in a functionally graded hollow cylinder (FGHC) made of metal/ceramic for a two‐dimensional fluid and wall conduction subject to Newton boundary condition is considered. The fluid and FGHC energy equations are coupled through the continuity of temperature and heat flux...
The tremendous strength and light weight properties of Carbon nanotubes (CNTs)
have fascinated the interest of researchers and scientists towards using CNTs for thermal,
chemical, optical, electrical, structural and mechanical applications. This paper presents
analytical solutions to the nonlinear dynamic response, shear force and bending moment
of...
In this study, nonlinear thermal-mechanical stability and vibration analysis of different end-shaped single-walled carbon nanotube conveying viscous nano-magnetic fluid embedded in nonlinear visco-elastic foundation under the influence of magnetic fields are presented. The development of the equation of motion was based on Euler-Bernoulli theory, H...
In this study, experiments were conducted for the flow of R-134a condensing in an enhanced inclined tube at a saturation condensing temperature of 40 °C. The enhanced tube had a helix angle of 14° with a mean internal diameter of 8.71 mm. The mass velocities were varied from 200 to 600 kg m−2 s−1, while the inclination angles were varied from − 90°...
The high strength-to-weight ratio and flexibility of single walled carbon nanotubes (SWCNT) make them of potential use in the control of nanoscale structures for thermal, electrical, structural and mechanical applications. This indicates that they will have a vital contribution to nanotechnology engineering. This paper presents an exact solution to...
The heat transfer performance of bilayered composite systems through which thermally developing laminar fluids flow for cases in which axial conduction is either significant or negligible has been investigated. The heat transfer problems considered as two dimensional conjugate problems with appropriate boundary conditions were solved via computatio...
![Fig. 4. Comparison between the present study and Gnielinski equation [48].](profile/Ekene-Onyiriuka/publication/335792647/figure/fig3/AS:802701151580162@1568390276921/Comparison-between-the-present-study-and-Gnielinski-equation-48_Q320.jpg)
In this study, the heat transfer characteristics of a new class of nanofluids made from mango bark was numerically simulated and studied during turbulent flow through a double pipe heat exchanger. A range of volume fractions was considered for a particle size of 100 nm. A two-phase flow was considered using the mixture model. The mixture model gove...
This paper presents experimental heat transfer and pressure drop measurements during the condensation of R134a at a mean saturation temperature of 40 °C inside a microfinned copper tube with an inner diameter of 8.92 mm and a helix angle of 14°. Experiments were conducted for mean qualities from 0.1 to 0.9 at different inclination angles ranging fr...
This paper presents the thermal performance of smooth and microfin tubes and the enhancement factors as they respond to inclination angle, mass flux and vapour quality in inclined tubes of 1.488 m long, 9.55 mm outer diameter during the convective condensation of R134a at the saturation temperature of 40oC. For the experiment, the quality was varie...
This paper presents the investigation of the conjugate heat transfer in a fluid conveying bilayered composite cylindrical pipe subjected to external convection. The problem is considered a two-dimensional problem in each of the three media. A finite difference scheme is employed to discretize the differential equations for the three media and conju...
Direct steam generation coupled with solar energy is a promising technology which can reduce the dependency on fossil fuels. It has the potential to impact the power-generation sector as well as industrial sectors where significant quantities of process steam are required. Compared to conventional concentrated solar power systems, which use synthet...
The transverse vibration of a pressurized, hot, flexible fluid-conveying pipe is investigated analytically via a coupled nonlinear partial differential equation where the effects of operating variables such as internal fluid temperature variation, mass ratio, pipe thickness, internal pressurization, Coriolis effect, axial acceleration of the intern...
In this study, the transverse natural frequencies of a pressurized hot fluid conveying pipe is investigated using complex mode function. Employing the dispersive relations and the non-trivial solution of the coefficient matrix obtained from the boundary equations, the eigenvalues and the linear natural frequencies are obtained numerically. The para...
The aim of this work is to conduct three-dimensional unsteady numerical simulations of turbulent condensing flows of R134a. The simulations, which are validated against experimental results, are performed in a horizontal tube with inner diameter 8.38 mm and length 1.488 m using a commercial CFD solver, ANSYS Fluent 18.0. The effect of varying quali...
An experimental study of convective condensation heat transfer of R134a was conducted in an inclined smooth copper tube of inner diameter of 8.38 mm. The mean vapour quality ranged between 0.1 and 0.9, mass flux between 200 kg/m2s and 400 kg/m2s, inclination angle between -90o (vertical downward) and +90o (vertical upward) at saturation temperature...
This paper presents the experimental heat transfer coefficient and frictional pressure drop values during the condensation of R134a inside a smooth copper tube for vapour qualities of 0.25, 0.5 and 0.75, mass fluxes of 200 kg/m 2 s to 300 kg/m 2 s, saturation temperatures of 30°C and 40°C and tube inclination angles ranging between-90° (vertical do...
The present paper reports on the two-phase frictional pressure drop calculated during the condensation of R134a in a tube of inner diameter of 8.38 mm at different inclination angles. The pressure drops were calculated using the most recent void fraction model of Bhagwat and Ghajar. The condensation tests were carried out in an experimental test fa...
Heat exchangers in heat pumps, refrigeration and airconditioning systems play a vital role in industrial and domestic applications whether for human comfort, preservation of farm produce, or for cooling of heat-emitting appliances or equipment. These heat-exchanging systems condense at different design temperatures, for example, power stations (whe...
In this study, the nonlinear transverse vibration of a flexible pipe conveying hot, pressurized fluid is investigated. The pipe which is subjected to a pinned-pinned end condition extends as a result of several operating variables such as internal fluid temperature variation, pre-stress and internal pressurization. The equation of motion is solved...
The study of internal chemical processes involving nitrogenous species forms an important part in the understanding of parameters which lower NOx emission from combustion systems. The focus of this research is to numerically model the prediction of formation of pollutant emission in a continuous internal combustion engine (ICE), from finite rate ch...
This paper presents the effects of saturation temperature and inclination angle on convective heat transfer during condensation of R134a in an inclined smooth copper tube of inner diameter of 8.38 mm. Experiments were conducted for inclination angles ranging from −90° (vertical downward) to +90° (vertical upward) for mass fluxes between 100 kg/m2s...
Conjugate heat transfer in laminar tube flow with convective boundary conditions is considered analytically. The steady state problem involving two-dimensional wall and fluid axial conduction and advection is solved using separation of variables for a thick walled cylindrical pipe. The effects of the Peclet number, external Biot number and wall-to-...
An experimental study of convective condensation heat transfer of R134a was conducted in an inclined smooth copper tube of inner diameter of 8.38 mm. The test condenser had a straight copper tube section with an effective length of 1.488 m and was cooled by water circulated in the surrounding annulus in a counter-flow arrangement. The rate of heat...
Solar dryers are imperative for the tropical and sub-Saharan African countries, which are faced with the duo challenges of inadequate electrical energy supply, which has severely limited the application of conventional refrigeration as a means of preservation of agricultural produce, and the need to make produce competitive in the international mar...
This paper looks at three socio-economic variables in energy consumption framework for energy planning in Nigeria. The consumption of dual purpose kerosene (DPK) was regressed against the real gross domestic product (GDP), commodity's price, and the lagged variable considering a period of 32 years (1970-2001). A statistical model was developed for...
Most of the attempts made at designing shell and tube heat exchangers have been limited to thermal hydraulic design. This study however, considers both the thermal and mechanical design of the E-type shell and tube heat exchanger with the aid of computer programming. It involves developing a simple user-friendly computer programme for the heat tran...
The need for renewable and environmentally friendlier energy sources has led to intensified efforts with respect to research in that area. One of such endeavours is the production of biofuels from various sources of vegetable oils. Therefore, this work is aimed at producing biodiesel from freshly prepared and clean palm kernel oil and groundnut oil...
�igeria is yet to develop a comprehensive scheme which is required to solve the current and persisting problem
of waste management in the country. Whereas the crude methods of sorting wastes practiced may be efficient, it
wastes useful time; hence the need for a mechanized sorting machine. An attempt has been made to develop a
waste sorting machine...
The photovoltaic (pv) forced convection solar dryer comprises the solar collector, dryer and pv assemblies. It is designed for a continuous operation throughout the day. The direct solar irradiation is utilized during sunshine hours and it automatically switches power supply to the battery during cloud covers and non-insolation periods. The inclusi...
In this study, a forced convection solar dryer was designed, constructed and tested for the purpose of drying yam in order to study the moisture removal pattern. Some pieces of yam fillets weighing, 0.52kg, were dried in the dryer while an equal mass was dried in the open sun (control) and the profiles obtained in both cases were compared. Also, ev...
The influence of soil sedimentation on the pipe walking phenomenon is investigated analytically via a set of coupled nonlinear partial differential equations where the effects of operating variables such as internal fluid temperature variation, prestress and internal pressurization, Coriolis and axial accelerations of the internal fluid and cross s...
A high speed abrasive cutting machine was designed and developed. The abrasive wheel of 4mm thickness was used and the speed was 2500 rpm. It is driven by an electric motor having a power of about 3.67 kW. Tests results on the machine showed that it can cut 25mm and 60mm mild steel rods in 7.5s and 21.3s respectively; 25mm and 60mm stainless steel...
This solar conversion system incorporates a suction fan powered by a solar PV module. Located at the outlet of the chamber is the d.c suction fan utilised to achieve forced air circulation without the use of external power supply like grid electricity, fossil fuel and battery. Simple thermal energy balance equations and heat transfer equations were...
In oil and gas installations, whether on-shore or off-shore, pipes are the primary vessel for the conveyance of either crude or products from one location to another. Under use, the pipes are subjected to both internal and external temperature fluctuations while repeated operational start-up and shut-down procedures triggers vibrations of these pip...
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ABSTRACT
Studies on condensation inside smooth inclined tubes have received very little attention as previous works have focused majorly on horizontal and vertical tube orientations. Few previous studies on inclined tubes were at high mass fluxes wherein it was found that the effect of inclination on the heat transfer coefficients became more pronounced by decreasing the mass flux and vapour quality. It was also found that tilting the tube at different angles of inclination influenced the flow pattern and altered the position of the liquid phase of the working fluid. In few studies involving low mass fluxes, it was found that the heat transfer coefficients were dependent on the temperature difference between the average saturation temperature and the temperature of the wall on which the condensation occurred. However, no study has coupled the effect of inclination and temperature difference on the heat transfer coefficients and flow patterns at low mass fluxes.
