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

Author(s):  
Rho-Shin Myong ◽  
Dong-Ho Lee ◽  
Jin-Hee Lee

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.

1970 ◽  
Author(s):  
V. P. Motulevich ◽  
M.S. Bespalov ◽  
A.N. Boyko ◽  
V. M. Eroshenko ◽  
E. D. Sergievskii ◽  
...  

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Stéphane Colin

Accurate modeling of gas microvection is crucial for a lot of MEMS applications (microheat exchangers, pressure gauges, fluidic microactuators for active control of aerodynamic flows, mass flow and temperature microsensors, micropumps, and microsystems for mixing or separation for local gas analysis, mass spectrometers, vacuum, and dosing valves…). Gas flows in microsystems are often in the slip flow regime, characterized by a moderate rarefaction with a Knudsen number of the order of 10−2–10−1. In this regime, velocity slip and temperature jump at the walls play a major role in heat transfer. This paper presents a state of the art review on convective heat transfer in microchannels, focusing on rarefaction effects in the slip flow regime. Analytical and numerical models are compared for various microchannel geometries and heat transfer conditions (constant heat flux or constant wall temperature). The validity of simplifying assumptions is detailed and the role played by the kind of velocity slip and temperature jump boundary conditions is shown. The influence of specific effects, such as viscous dissipation, axial conduction and variable fluid properties is also discussed.


2020 ◽  
Vol 538 ◽  
pp. 122783 ◽  
Author(s):  
Samina Javed ◽  
Hafiz Muhammad Ali ◽  
Hamza Babar ◽  
Muhammad Sajid Khan ◽  
Muhammad Mansoor Janjua ◽  
...  

2008 ◽  
Author(s):  
Jinliang Yuan ◽  
Guogang Yang ◽  
Bengt Sunde´n

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.


2013 ◽  
Vol 5 (3) ◽  
pp. 321-328 ◽  
Author(s):  
Kuerbanjiang Wusiman ◽  
Md. J. Nine ◽  
Kelimu Tulugan ◽  
Handry Afrianto ◽  
Yoon Sub Eom ◽  
...  

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