Topic
Heat transfer
About: Heat transfer is a research topic. Over the lifetime, 181795 publications have been published within this topic receiving 2923586 citations. The topic is also known as: heat exchange.
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TL;DR: In this article, the discrete-ordinates equations were formulated for an absorbing, anisotropic scattering, and re-emitting medium enclosed by gray walls and the conditions for computational stability were presented.
Abstract: Radiative heat transfer in a three-dimensional participating medium was predicted using the discrete-ordinates method. The discrete-ordinates equations are formulated for an absorbing, anisotropically scattering, and re-emitting medium enclosed by gray walls. The solution strategy is discussed and the conditions for computational stability are presented. Several test enclosures are modeled. Results have been obtained for the S2, S4, S6, and S8 approximation s that correspond to 8, 24, 48, and 80 fluxes, respectively, and are compared with the exact-zone solution and the P3 differential approximation. Solutions are found for conditions that simulate absorbing media and isotropically and anisotropically scattering media. Solution accuracy and convergence are discussed for the various flux approximations. The S4, S6, and S8 solutions compare favorably with the other methods and can be used to predict radiant intensity, incident energy, and surface heat flux. A an bn B C E G / L n q r S x y z a /U,,£,TJ p a a © V Nomenclature = north-south areas, m2 = coefficients of a Legendre series = coefficients of a modified Legendre series = east-west areas, m2 = front-back areas, m2 = emissive power ( = aT4), W/m2 = incident energy, /4w/d6, W/m2 = radiant intensity, W/(m2 • Sr) = enclosure dimension, m = unit normal = heat flux, W/m2 = position vector, m = source term, W/m3 = volume of pth control volume, m3 = weight function in a direction - m (fractional area of a unit sphere) = coordinate, m = coordinate, m = coordinate, m — finite-difference weighting factor = extinction coefficient, a -f K,m~l = surface emittance = absorption coefficient, m"1 = ordinates p = cos0, £ = sin0 sin , TJ = sinG cos = outgoing direction of radiation = phase function = surface reflectance = scattering coefficient, m"1 = Boltzmann's constant, 5.669 X 1(T 8 W/(m2
378 citations
TL;DR: The main features of the problems addressed with GAs including the modeling, number of variables, and GA settings are presented, useful for future use of GAs in heat transfer.
378 citations
TL;DR: In this article, the analysis of laminar mixed convection in boundary layers adjacent to a vertical, continuously stretching sheet has been presented, where the velocity and temperature of the sheet were assumed to vary in a power-law form.
Abstract: The analysis of laminar mixed convection in boundary layers adjacent to a vertical, continuously stretching sheet has been presented. The velocity and temperature of the sheet were assumed to vary in a power-law form, that is, u
w
(x)=Bx
m
and T
w
(x)−T
∞=Ax
n
. In the presence of buoyancy force effects, similarity solutions were reported for the following two cases: (a) n=0 and m=0.5, which corresponds to an isothermal sheet moving with a velocity of the form u
w
=Bx
0.5 and (b) n=1 and m=1, which corresponds to a continuous, linearly stretching sheet with a linear surface temperature distribution, i.e. T
w
−T
∞=Ax. Formulation of the present problem shows that the heat transfer characteristics depends on four governing parameters, namely, the velocity exponent parameter m, the temperature exponent parameter n, the buoyancy force parameter G
*, and Prandtl number of the fluid. Numerical solutions were generated from a finite difference method. Results for the local Nusselt number, the local friction coefficient, and temperature profiles are presented for different governing parameters. Effects of buoyancy force and Prandtl number on the flow and heat transfer characteristics are thoroughly examined.
378 citations
Book•
07 Nov 2000
TL;DR: The Quadrupole approach applied to heat transfer in semi-transparent materials is discussed in this article, where the quadrupoles are applied to Heat Transfer in Semi-Transparent Materials.
Abstract: Interest in the Quadrupole Approach. Linear Conduction and Simple Geometries. One--Dimensional Quadrupoles. Multidimensional Transfers. Time--Dependent Periodic Regimes. Advanced Quadrupoles. Mass Transfer in a Porous Medium. The Quadrupole Approach Applied to Heat Transfer in Semi--Transparent Materials. Inverse Laplace Transform. Appendices. Index.
378 citations
TL;DR: In this paper, the authors present new correlations for the convective heat transfer and the friction factor developed from the experiments of nanoparticles comprised of aluminum oxide, copper oxide and silicon dioxide dispersed in 60% ethylene glycol and 40% water by mass.
378 citations