scholarly journals Heat Transfer in the Flow of a Cold, Axisymmetric Jet Over a Hot Sphere

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Jian-Jun Shu ◽  
Graham Wilks
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
Thickness Distribution ◽  
Working Fluid ◽  
Thin Film Flow ◽  
Axisymmetric Jet ◽  
Keller Box Method ◽  
Physical Features ◽  
Vertical Jet ◽  
Good Agreement

The heat-transfer characteristics of thin film flow over a hot sphere resulting from a cold vertical jet of liquid falling onto the surface have been investigated. The underlying physical features have been illustrated by numerical solutions of high accuracy based on the modified Keller box method. The solutions for film thickness distribution are good agreement with those obtained approximately by using the Pohlhausen integral momentum technique and observed experimentally by using water as working fluid, thus providing a basic confirmation of the validity of the results presented.

scholarly journals Heat Transfer in the Flow of a Cold, Axisymmetric Vertical Liquid Jet Against a Hot, Horizontal Plate

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Jian-Jun Shu ◽  
Graham Wilks
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Numerical Solutions ◽  
Reynolds Numbers ◽  
Thin Film Flow ◽  
Keller Box Method ◽  
Box Method ◽  
Parallel Approximation ◽  
Vertical Jet ◽  
Good Agreement

The paper considers heat transfer characteristics of thin film flow over a hot horizontal flat plate resulting from a cold vertical jet of liquid falling onto the surface. A numerical solution of high accuracy is obtained for large Reynolds numbers using the modified Keller box method. For the flat plate, solutions for axisymmetric jets are obtained. In a parallel approximation theory, an advanced polynomial approximation for the velocity and temperature distribution is employed and results are in good agreement with those obtained using a simple Pohlhausen polynomial and the numerical solutions.

scholarly journals Flow and Heat Transfer at a Nonlinearly Shrinking Porous Sheet:The Case of Asymptotically Large Powerlaw Shrinking Rates

2013 ◽  
Vol 18 (3) ◽  
pp. 779-791 ◽  
Author(s):  
K.V. Prasad ◽  
K. Vajravelu ◽  
I. Pop
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Power Law ◽  
Numerical Solutions ◽  
Skin Friction Coefficient ◽  
Temperature Fields ◽  
Shrinking Sheet ◽  
Arbitrary Power ◽  
Keller Box Method ◽  
Flow And Heat Transfer

Abstract The boundary layer flow and heat transfer of a viscous fluid over a nonlinear permeable shrinking sheet in a thermally stratified environment is considered. The sheet is assumed to shrink in its own plane with an arbitrary power-law velocity proportional to the distance from the stagnation point. The governing differential equations are first transformed into ordinary differential equations by introducing a new similarity transformation. This is different from the transform commonly used in the literature in that it permits numerical solutions even for asymptotically large values of the power-law index, m. The coupled non-linear boundary value problem is solved numerically by an implicit finite difference scheme known as the Keller- Box method. Numerical computations are performed for a wide variety of power-law parameters (1 < m < 100,000) so as to capture the effects of the thermally stratified environment on the velocity and temperature fields. The numerical solutions are presented through a number of graphs and tables. Numerical results for the skin-friction coefficient and the Nusselt number are tabulated for various values of the pertinent parameters.

scholarly journals Combined Experimental and CFD Investigation of the Parabolic Shaped Solar Collector Utilizing Nanofluid (CuO-H2O and SiO2-H2O) as a Working Fluid

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Ketan Ajay ◽  
Lal Kundan
Keyword(s):  
Heat Transfer ◽  
Solar Collector ◽  
Volume Concentration ◽  
Working Fluid ◽  
Ansys Fluent ◽  
Heat Transfer Fluids ◽  
Different Types ◽  
Average Size ◽  
20 Nm ◽  
Good Agreement

Nanoscience application plays a major role in heat transfer related problems. A nanofluid is basically a suspension of fine sized nanomaterials in base fluids like water, Therminol VP-1, ethylene glycol, and other heat transfer fluids. This paper evaluates the possible application of nanofluid in parabolic shaped concentrating solar collector using both experimental and CFD analysis. Different types of nanomaterials used are SiO2and CuO of 20 nm average size. Nanofluids of SiO2-H2O (DI) and CuO-H2O (DI) of 0.01% volume concentration are used. Flow rates of 40 LPH and 80 LPH are used. ANSYS FLUENT 14.5 is used for carrying out CFD investigation. 3D temperature distribution of absorber tube is obtained using numerical investigation and the result is compared with the experimental one. Improvement in efficiency of collector of about 6.68% and 7.64% is obtained using 0.01% vol. conc. SiO2-H2O (DI) nanofluid and 0.01% vol. conc. CuO-H2O (DI) nanofluid, respectively, as compared to H2O (DI) at 40 LPH while at 80 LPH improvement in efficiency of collector of about 7.15% and 8.42% is obtained using 0.01% vol. conc. SiO2-H2O (DI) nanofluid and 0.01% vol. conc. CuO-H2O (DI) nanofluid, respectively, as compared to H2O (DI). Both experimental and CFD temperature results are in good agreement.

An Experimental and Theoretical Study of Heat Transfer in Vertical Tube Flows

1978 ◽  
Vol 100 (1) ◽  
pp. 86-91 ◽  
Author(s):  
R. Greif
Keyword(s):  
Heat Transfer ◽  
Turbulent Flows ◽  
Theoretical Study ◽  
Numerical Solutions ◽  
Reynolds Numbers ◽  
Vertical Tube ◽  
Laminar Flows ◽  
Radial Temperature ◽  
Rayleigh Numbers ◽  
Good Agreement

An experimental and theoretical study was carried out for the heat transfer in laminar and turbulent tube flows with air and argon. Radial temperature profiles were measured at a location 108 tube diameters from the inlet of the vertical, electrically heated test section. The temperature of the tube wall was also measured. The experimental data were in good agreement with the results obtained from numerical solutions of the conservation equations and from simplified, fully developed solutions. For turbulent flows the Reynolds numbers varied from 10,000 to 19,500; for laminar flows the Reynolds numbers varied from 1850 to 2100 while the Rayleigh numbers varied from 70 to 80.

Optimal Perturbation Iteration Method for Solving Nonlinear Heat Transfer Equations

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Sinan Deniz
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Iteration Method ◽  
Numerical Solutions ◽  
Nonlinear Differential Equations ◽  
Optimal Perturbation ◽  
Transfer Equations ◽  
Better Than ◽  
Good Agreement ◽  
Distribution Equation

In this paper, the new optimal perturbation iteration method (OPIM) is introduced and applied for solving nonlinear differential equations arising in heat transfer. The effectiveness of the proposed method will be tested by considering two specific applications: the temperature distribution equation in a thick rectangular fin radiation to free space and cooling of a lumped system with variable specific heat. Comparing different methods shows that the results obtained by optimal perturbation iteration method are very good agreement with the numerical solutions and perform better than the most existing analytic methods.

Heat Transfer Investigation of an Additively Manufactured Minichannel Heat Exchanger

2019 ◽  
Author(s):  
Hamidreza Rastan ◽  
Amir Abdi ◽  
Monika Ignatowicz ◽  
Bejan Hamawandi ◽  
Poh Seng Lee ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Single Phase ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Working Fluid ◽  
Minichannel Heat Exchanger ◽  
Simulation Results ◽  
Good Agreement

Abstract This study investigates the thermal performance of laminar single-phase flow in an additively manufactured minichannel heat exchanger both experimentally and numerically. Distilled water was employed as the working fluid, and the minichannel heat exchanger was made from aluminum alloy (AlSi10Mg) through direct metal laser sintering (DMLS). The minichannel was designed with a hydraulic diameter of 2.86 mm. The Reynolds number ranged from 175 to 1360, and the heat exchanger was tested under two different heat fluxes of 1.5 kWm−2 and 3 kWm−2. A detailed experiment was conducted to obtain the thermal properties of AlSi10Mg. Furthermore, the heat transfer characteristics of the minichannel heat exchanger was analyzed numerically by solving a three-dimensional conjugate heat transfer using the COMSOL Multiphysics® to verify the experimental results. The experimental results were also compared to widely accepted correlations in literature. It is found that 95% and 79% of the experimental data are within ±10% range of both the simulation results and the values from the existing correlations, respectively. Hence, the good agreement found between the experimental and simulation results highlights the possibility of the DMLS technique as a promising method for manufacturing future multiport minichannel heat exchangers.

Heat Transfer in a Thin-Film Flow in the Presence of Squeeze and Shear Thinning: Application to Piston Rings

1997 ◽  
Vol 119 (2) ◽  
pp. 249-257 ◽  
Author(s):  
D. J. Radakovic ◽  
M. M. Khonsari
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Piston Ring ◽  
Numerical Solutions ◽  
Combustion Engine ◽  
Plane Surface ◽  
Shear Thinning ◽  
Viscous Drag ◽  
Thin Film Flow ◽  
Viscous Drag Force

The governing equations and appropriate numerical solutions are presented for the heat transfer and the flow of a shear thinning fluid confined between a curved and plane surface in a thin-film configuration. One surface undergoes a reciprocating motion and the fluid experiences transverse squeeze action, as in a typical piston ring of an internal combustion engine. The effect of viscosity variations with temperature, in conjunction with the non-Newtonian shear thinning behavior of multigrade oils, are included in the analysis. Extensive numerical simulations of the performance of the piston are presented and compared to the isothermal Newtonian solutions. Computations show that shear thinning can have a significant effect on parameters such as film thickness, viscous drag force, and power loss. The thermal effects from viscous dissipation in the clearance space along the piston ring also influence these parameters, but to a lesser degree.

scholarly journals Flow and heat transfer of aligned magnetic field with Newtonian heating boundary condition

2018 ◽  
Vol 189 ◽  
pp. 01005
Author(s):  
A R M Kasim ◽  
N S Arifin ◽  
S M Zokri ◽  
M Z Salleh
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Boundary Layer ◽  
Boundary Condition ◽  
Numerical Solutions ◽  
Newtonian Heating ◽  
Boundary Layer Equations ◽  
Keller Box Method ◽  
Flow And Heat Transfer ◽  
Aligned Magnetic Field

Influence of aligned magnetic field on the steady boundary layer flow and heat transfer over a stretching sheet with Newtonian heating boundary condition is considered. The transformed governing nonlinear boundary layer equations in the form of ordinary differential equations are solved numerically by Keller box method. The details on computation have been presented and elaborated. The obtained numerical solutions have been captured graphically in the form of velocity and temperature distributions for different values of aligned angle, magnetic field parameter, Prandtl number and conjugate parameter. It is found that, increases in aligned angle associated with magnetic field delayed the velocity profile of the flow and enhances the temperature profile.

Effects of Gravity and Surface Tension and Interfacial-Waves and Heat-Transfer Rates in Internal Condensing Flows

2003 ◽  
Author(s):  
Q. Liang ◽  
X. Wang ◽  
A. S. Barve ◽  
A. Narain
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Numerical Solutions ◽  
Film Condensation ◽  
Vapor Flow ◽  
Transfer Rates ◽  
Condensing Flows ◽  
Steady Solutions ◽  
Internal Condensing Flows ◽  
Good Agreement

The paper presents accurate numerical solutions of the full 2D governing equations for steady and unsteady laminar/laminar internal condensing flows. The chosen geometry allows for film condensation on the bottom wall of a tilted (from vertical to horizontal) channel. It is found that it is important to know whether the exit conditions are constrained or unconstrained because incompressible vapor flows occur only for exit conditions that are unconstrained. For the incompressible vapor flow situations, a method for computationally obtaining the stable steady/quasi-steady solutions is given here and the resulting solutions are shown to be in good agreement with some relevant experimental data for horizontal channels. These solutions are shown to be sensitive to the frequency-content and strength of ever-present minuscule transverse vibrations of the condensing surface. The effects of noise-sensitivity, gravity (terrestrial to zero-gravity), and surface tension on the attainability of stable steady/quasi-steady solutions, structure of superposed waves, and heat-transfer rates are discussed. It is shown that significant enhancement in wave-energy and heat-transfer rates are possible by designing the condensing surface noise to be in resonance with the intrinsic waves.

Heat Transfer Analysis on a Thermosyphon Radiator

2011 ◽  
Vol 347-353 ◽  
pp. 659-663
Author(s):  
Zheng Zuo ◽  
Qing Hai Luo
Keyword(s):  
Heat Transfer ◽  
Experimental Tests ◽  
Heat Transfer Analysis ◽  
Working Fluid ◽  
Analysis Model ◽  
Advantages And Disadvantages ◽  
Good Agreement

Heat transfer of a thermosyphon radiator was analyzed, experimental tests with acetone as working fluid have been performed, and good agreement between measurement and calculation with analysis model was obtained. Compared with conventional radiator by means of experiments and analysis, the advantages and disadvantages of the thermosyphon radiator were discussed.

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