Internal Laminar Heat Transfer With Gas-Property Variation

1971 ◽  
Vol 93 (4) ◽  
pp. 432-440 ◽  
Author(s):  
T. B. Swearingen ◽  
D. M. McEligot
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
Bulk Temperature ◽  
Parallel Plates ◽  
Temperature Dependent ◽  
Property Variation ◽  
Constant Wall Heat Flux ◽  
Mixed Mean ◽  
Two Dimensional Flow ◽  
Temperature Dependent Properties

The results of a numerical investigation of internal laminar heat transfer to a gas with temperature-dependent properties are reported. In this investigation the authors obtained numerical solutions to the coupled partial differential equations of continuity, energy, momentum, and integral continuity describing the two-dimensional flow of perfect gas between heated parallel plates. A sequence of numerical solutions was obtained for the case of constant wall heat flux with a fully developed velocity profile at the start of the heated section and pure forced convection. The results may be summarized by Nu=Nuconst.prop.+0.024(Q+)0.3(Gzm)0.75f·Rem=24(Twall/Tbulk) where the subscript “m” refers to properties evaluated at the local mixed-mean (or bulk) temperature.

An Approximate Method for Predicting Laminar Heat Transfer Between Parallel Plates Having Embedded Heat Sources

1995 ◽  
Vol 117 (1) ◽  
pp. 63-68 ◽  
Author(s):  
R. S. Figliola ◽  
P. G. Thomas
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Approximate Method ◽  
Numerical Solutions ◽  
Convection Heat Transfer ◽  
Flow Regimes ◽  
Experimental Result ◽  
Heat Sources ◽  
Parallel Plates ◽  
Two Dimensional Flow

An approximate method for predicting the forced convection heat transfer for flow between parallel plates having embedded, discrete heat sources on one or both sides is presented. The spacing between sources is considered as adiabatic and the two-dimensional flow is laminar. The characteristics of such a flow can be described as flow in the isolated plate, developing flow, and fully developed flow regimes. The analysis uses appropriate forms for the surface temperature and Nusselt number solutions for the flow regimes encountered. Superposition is then applied to develop the discrete array solution for temperature and Nusselt number regardless of the arbitrary and step nature of the boundary conditions. Comparisons to existing numerical solutions show good agreement to within five percent of the predicted temperatures. A direct simulation of an existing experimental result shows reasonable agreement in the Nusselt number solution. These results validate the methodology for practical use including electronic cooling applications.

A Historical Misperception on Calculating the Average Convection Coefficient in Tubes With Constant Wall Heat Flux

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Ted D. Bennett
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Exact Solutions ◽  
Wall Heat Flux ◽  
First Principle ◽  
Convection Coefficient ◽  
Parallel Plates ◽  
Historical Approach ◽  
First Principle Calculations ◽  
Constant Wall Heat Flux

The historical approach to averaging the convection coefficient in tubes of constant wall heat flux leads to quantitative errors in short tubes as high as 12.5% for convection into fully developed flows and 33.3% for convection into hydrodynamically developing flows. This mistake can be found in teaching texts and monographs on heat transfer, as well as in major handbooks. Using the correctly defined relationship between local and average convection coefficients, eight new correlations are presented for fully developed and developing flows in round tubes and between parallel plates for the constant wall heat flux condition. These new correlations are within 2% of exact solutions for fully developed flows and within 6% of first principle calculations for hydrodynamically developing flows.

scholarly journals The NANOFLUID FLOW BETWEEN PARALLEL PLATES AND HEAT TRANSFER IN PRESENCE OF CHEMICAL REACTION AND POROUS MATRIX

2020 ◽  
Vol 50 (4) ◽  
pp. 283-289
Author(s):  
S. Jena ◽  
S. R. Mishra ◽  
P.K. Pattnaik ◽  
Ram Prakash Sharma
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Chemical Reaction ◽  
Numerical Solutions ◽  
Porous Matrix ◽  
Parallel Plates ◽  
Nanofluid Flow ◽  
Similarity Transformations ◽  
Fourth Order Method ◽  
Source Sink

This paper deals with nanofluid flow between parallel plates and heat transfer through porous media with heat source /sink. The governing equations are transformed into self-similar ordinary differential equations by adopting similarity transformations and then the converted equations are solved numerically by Runge-Kutta fourth order method. Special emphasis has been given to the parameters of physical interest which include Prandtl number, magnetic parameter, porous matrix, chemical reaction parameter and heat source parameter. The results obtained for velocity, temperature and concentration are shown in graphs. The comparison of the special case of this present results with the existing numerical solutions in the literature shows excellent agreement.

scholarly journals TURBULENCE MODELS APPLIED TO CLASSICAL FLUID MECHANICS AND HEAT TRANSFER PROBLEMS - THE PERFORMANCE EVALUATION OF THE OPEN SOURCE CFD PACKAGE OPENFOAM

2021 ◽  
Vol 1 (5) ◽  
pp. e1539
Author(s):  
Paulo Rocha ◽  
Felipe Pinto Marinho ◽  
Victor Oliveira Santos ◽  
Stéphano Praxedes Mendonça ◽  
Maria Eugênia Vieira da Silva
Keyword(s):  
Heat Transfer ◽  
Fluid Mechanics ◽  
Open Source ◽  
Numerical Solutions ◽  
Turbulence Modeling ◽  
Air Flow ◽  
Turbulence Models ◽  
Parallel Plates ◽  
Averaged Equations ◽  
Rans Turbulence Models

Topics related to the modeling of turbulent flow feature significant relevance in several areas, especially in engineering, since the vast majority of flows present in the design of devices and systems are characterized to be turbulent. A vastly applied tool for the analysis of such flows is the use of numerical simulations based on turbulence models. Thus, this work aims to evaluate the performance of several turbulence models when applied to classic problems of fluid mechanics and heat transfer, already extensively validated by empirical procedures. The OpenFOAM open source software was used, being highly suitable for obtaining numerical solutions to problems of fluid mechanics involving complex geometries. The problems for the evaluation of turbulence models selected were: two-dimensional cavity, Pitz-Daily, air flow over an airfoil, air flow over the Ahmed blunt body and the problem of natural convection between parallel plates. The solution to such problems was achieved by utilizing several Reynolds Averaged  Equations (RANS) turbulence models, namely: k-ε, k-ω, Lam-Bremhorst k-ε, k-ω SST, Lien-Leschziner k-ε, Spalart-Allmaras, Launder-Sharma k-ε, renormalization group (RNG) k-ε. The results obtained were compared to those found in the literature which were empirically obtained, thus allowing the assessment of the strengths and weaknesses of the turbulence modeling applied in each problem.

Detailed Description of the Fluidized Bed Mixing and Heat Transfer by Means of Eulerian Multi-Fluid Numerical Simulations

2020 ◽  
Author(s):  
Muhammad Ali Uzair ◽  
Francesco Fornarelli ◽  
Sergio Mario Camporeale ◽  
Marco Torresi
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Granular Flow ◽  
Fluid Model ◽  
Gas Velocity ◽  
Uniform Temperature ◽  
Temperature Dependent ◽  
Commercial Code ◽  
Temperature Dependent Properties ◽  
Superficial Gas Velocity

Abstract The hydrodynamics and heat transfer of a binary mixture of sand and biomass in a fluidized bed have been numerically investigated. The Eulerian multi-fluid model MFM incorporating kinetic theory of granular flow was used to numerically investigate fluidized bed. A commercial code has been used together with user-defined functions to correctly predict the hydrodynamics and the heat transfer. Numerical results were validated against the experiment in terms of pressure drop across the bed and concentration of biomass at different heights of the bed. Influence of additional parameters, such as superficial gas velocity and sand sizes on hydrodynamics were investigated. Additionally, heat transfer in the fluidized bed was also studied highlighting the influence of the temperature dependent properties of air on the results. The present results reveal that better mixing is achieved for smallest sand size, also promoting more uniform temperature of biomass.

COMPARATIVE STUDY OF THERMAL FLOWS WITH DIFFERENT FINITE VOLUME AND LATTICE BOLTZMANN SCHEMES

2004 ◽  
Vol 15 (02) ◽  
pp. 307-319 ◽  
Author(s):  
AHMAD AL-ZOUBI ◽  
GUNTHER BRENNER
Keyword(s):  
Heat Transfer ◽  
Comparative Study ◽  
Finite Volume ◽  
Lattice Boltzmann ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Hybrid Approach ◽  
Navier Stokes ◽  
Steady Flows ◽  
Parallel Plates

In the present paper, a comparative study of numerical solutions for steady flows with heat transfer based on the finite volume method (FVM) and the relatively new lattice Boltzmann method (LBM) is presented. In the last years, the LB methods have challenged the classical FV methods to solve the Navier–Stokes equations and have proven to be superior in accuracy and efficiency for certain applications. Most of these studies were related to the transport of mass and momentum. In the meantime, significant effort has been invested in the application of the LBM to simulate flows including heat transfer. The studies in the present paper are the analysis of performance and accuracy aspects of LBM applied to the prediction of these flows. For a fully developed laminar flow between parallel plates, analytical solutions for the heat transfer in fully developed thermal boundary layers are available and may be compared with the respective numerical results. Finally, a hybrid approach is proposed to circumvent numerical problems of the thermal LB methods.

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