RADIATION-CONVECTIVE HEAT TRANSFER BETWEEN GAS FLOW AND BLUNT BODIES OF POROUS INJECTION OF RADIATION ABSORBING SUBSTANCES

1970 ◽  
Author(s):  
V. P. Motulevich ◽  
M.S. Bespalov ◽  
A.N. Boyko ◽  
V. M. Eroshenko ◽  
E. D. Sergievskii ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Gas Flow ◽  
Blunt Bodies ◽  
Porous Injection

The Effect of Temperature Jump on Microscale Heat Transfer: Slip Models and the Moment Methods

2008 ◽  
Author(s):  
Rho-Shin Myong ◽  
Dong-Ho Lee ◽  
Jin-Hee Lee
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Gas Flow ◽  
Computational Models ◽  
Temperature Jump ◽  
Constitutive Relations ◽  
Flow Regimes ◽  
Effect Of Temperature ◽  
Microscale Heat Transfer

The study of non-linear transport in gas flows associated with micro and nanodevices has emerged as an important topic in recent years. In the field of microscale heat transfer, convective heat transfer in slip-flow regimes in simple geometries like channels and tubes is a key problem. Constant-wall-temperature convective heat transfer in microscale tubes and channels has been studied recently using analytical solutions to an extended Graetz problem. In addition, much effort has been put into the development of computational models beyond the theory of linear constitutive relations for the analysis of microscale gas flow and heat transfer, since the Navier-Stokes-Fourier theory is not known to remain valid in the flow regimes of large Knudsen number. The objective of the present paper is to investigate microscale heat transfer where temperature jump is the dominant phenomena. The emphasis will be on the qualitative features of microscale heat transfer, for example, enhancement or reduction of heat transfer in microscale geometries. General features of computational models such as the full kinetic model and fluid dynamics model are also discussed.

CFD Approach Analysis of Chemical Reactions Coupled Convective Heat Transfer in Reformer Ducts

2008 ◽  
Author(s):  
Jinliang Yuan ◽  
Guogang Yang ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Chemical Reactions ◽  
Convective Heat ◽  
Porous Layer ◽  
Gas Flow ◽  
Transport Processes ◽  
Fuel Gas ◽  
Steam Reformer ◽  
Flow Duct

Thermo-mechanical failure of components in a compact steam reformer is a major obstacle to bring this technology to real-life applications. The probability of material degradation and failure depends strongly on the convective heat transfer in the fuel gas flow duct and local temperature distribution in multifunctional materials. It is of significant importance to accurately predict the convective heat transfer coupled with catalytic reactions within the reformer components. In this paper, the simulation and analysis of combined chemical reactions and transport processes are conducted for a duct relevant for compact design steam reformer, which consists of a porous layer for the catalytic reforming reactions of methane, the fuel gas flow duct and solid plates. A fully three-dimensional computational fluid dynamics (CFD) approach is applied to calculate transport processes and effects of thermal conductivities of the involved multi-functional materials on convective heat transfer/temperature distributions, in terms of interface temperature gradients/heat fluxes and Nusselt numbers. The steam reformer conditions such as mass balances associated with the reactions and gas permeation to/from the porous anode are implemented in the calculation. The results show that the classic thermal boundary conditions (either constant heat flux or temperature, or combined one) may not be applicable for the interfaces between the fuel flow duct and solid plate/porous layer.

Pressure Work and Viscous Dissipation Effects on Heat Transfer in a Parallel–Plate Microchannel Gas Flow

2017 ◽  
Vol 35 (02) ◽  
pp. 243-254 ◽  
Author(s):  
K. M. Ramadan
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Viscous Dissipation ◽  
Convective Heat ◽  
Parallel Plate ◽  
Gas Flow ◽  
Combined Effect ◽  
Rarefaction Analysis ◽  
Pressure Work ◽  
Axial Conduction

ABSTRACTConvective heat transfer in a parallel plate microchannel gas flow is investigated analytically and numerically, considering the effects of viscous dissipation, pressure work, shear work, axial conduction and rarefaction. Analysis is performed with constant wall temperature and constant wall heat flux boundary conditions for both gas cooling and heating. The results presented demonstrate the significance of the combined effect of pressure work and viscous dissipation, shear work, rarefaction degree and axial conduction on microchannel convective heat transfer, in both the thermally developing and fully developed flow regions. Viscous dissipation and pressure work in a pressure-driven microchannel gas flow are of comparable magnitudes and may not be neglected from the energy equation. The shear work at the wall, which is effectively the combined effect of viscous dissipation and pressure work, needs to be included in the Nusselt number for better predictions of heat transfer.

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