Convective heat transfer in a vertical anisotropic porous layer

1996 ◽  
Vol 22 ◽  
pp. 116
Author(s):  
G Degan
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Porous Layer

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.

CFD Analysis of Two-Phase Flow and Convective Heat Transfer in PEMFC Ducts

2008 ◽  
Author(s):  
Jinliang Yuan ◽  
Huamin Zhang ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Porous Layer ◽  
Two Phase Flow ◽  
Active Surface ◽  
Main Stream ◽  
Phase Flow ◽  
Two Phase

In this study, a three-dimensional computational method was developed to predict convective heat transfer combined with water phase change/two-phase flow in a PEMFC cathode duct. Momentum, heat transport and species equations have been solved by coupled source terms and thermo-physical properties of the multi-component mixture. Advanced boundary conditions are applied at the cathode duct external walls in the analysis, i.e., combined thermal boundary conditions of heat flux on the active surface and thermal insulation on the remaining solid walls. Moreover, effects of mass consumption and generation appearing on the active surface are implemented. The calculated results reveal that the thermal conditions at the interfaces vary along the main stream, and a big permeability of the porous layer promotes the bulk gas transport and the generated liquid water removal via the bottom interface between the flow duct and the porous layer, and a big convective heat transfer coefficient as well.

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