scholarly journals Enhancing internal mass transport in Fischer–Tropsch catalyst layers utilizing transport pores

2016 ◽  
Vol 6 (1) ◽  
pp. 275-287 ◽  
Author(s):  
Henning Becker ◽  
Robert Güttel ◽  
Thomas Turek
Keyword(s):  
Mass Transport ◽  
Layer Thickness ◽  
Internal Mass ◽  
Dimensional Model ◽  
Fischer Tropsch ◽  
One Dimensional ◽  
Catalyst Layers ◽  
Pore Fraction

A one-dimensional model of Fischer–Tropsch catalyst layers is used for optimization of layer thickness and transport pore fraction to avoid diffusive restrictions and improve productivity.

Analysis for the Effect of Inverter Ripple Current on Fuel Cell Operating Condition

2001 ◽  
Author(s):  
Randall S. Gemmen
Keyword(s):  
Boundary Condition ◽  
Fuel Cell ◽  
Mass Transport ◽  
Transient Behavior ◽  
Mechanical State ◽  
Dimensional Model ◽  
One Dimensional ◽  
Fuel Cell Stack ◽  
A Cell ◽  
The Impact

Abstract The effect of inverter ripple current on fuel cell stack performance and stack lifetime remains uncertain. This paper provides a first attempt to examine the impact of inverter load dynamics on the fuel cell. Since reactant utilization is known to impact the mechanical state of a fuel cell, it is suggested that the varying reactant conditions surrounding the cell govern, at least in part, the lifetime of the cells. This paper investigates these conditions through the use of a dynamic model for the bulk conditions within the stack, as well as a one-dimensional model for the detailed mass transport occurring within the electrode of a cell. These two independent modeling approaches help to verify their respective numerical procedures. In this work, the inverter load is imposed as a boundary condition to the models. Results show the transient behavior of the reactant concentrations within the stack, and of the mass diffusion within the electrode under inverter loads with frequencies between 30 Hz and 1250 Hz.

Analysis for the Effect of Inverter Ripple Current on Fuel Cell Operating Condition

2003 ◽  
Vol 125 (3) ◽  
pp. 576-585 ◽  
Author(s):  
Randall S. Gemmen
Keyword(s):  
Boundary Condition ◽  
Fuel Cell ◽  
Mass Transport ◽  
Transient Behavior ◽  
Dimensional Model ◽  
One Dimensional ◽  
Fuel Cell Stack ◽  
A Cell ◽  
The Impact ◽  
Mechanical Nature

The effect of inverter ripple current on fuel cell stack performance and stack lifetime remains uncertain. This paper provides a first attempt to examine the impact of inverter load dynamics on the fuel cell. Since reactant utilization is known to impact the mechanical nature of a fuel cell, it is suggested that the varying reactant conditions surrounding the cell govern, at least in part, the lifetime of the cells. This paper investigates these conditions through the use of a dynamic model for the bulk conditions within the stack, as well as a one-dimensional model for the detailed mass transport occurring within the electrode of a cell. These two independent modeling approaches are used to verify their respective numerical procedures. In this work, the inverter load is imposed as a boundary condition to the models. Results show the transient behavior of the reactant concentrations within the stack, and of the mass diffusion within the electrode under inverter loads with frequencies between 30 Hz and 1250 Hz.

Gelification and mass transport in a static non-isothermal waxy solution

2009 ◽  
Vol 20 (1) ◽  
pp. 93-122 ◽  
Author(s):  
A. FASANO ◽  
L. FUSI ◽  
J. R. OCKENDON ◽  
M. PRIMICERIO
Keyword(s):  
Free Boundary ◽  
Mass Transport ◽  
Boundary Problem ◽  
Cloud Point ◽  
Free Boundary Problem ◽  
Mathematical Problem ◽  
Well Posedness ◽  
Dimensional Model ◽  
One Dimensional ◽  
A Free Boundary Problem

We consider a solution of a mono-component oil and wax. The latter is dissolved in the oil if the temperature is above the so-called cloud point (which depends on the concentration) and it segregates in the form of solid crystals if temperature is below the cloud point. As the solid fraction of wax increases, the diffusivity of liquid wax in the oil decreases (gelification), eventually vanishing. We study a one-dimensional model where temperature is initially above the cloud point and then it is lowered to induce diffusion and gelification. We formulate the relevant mathematical problem (a free boundary problem), studying its well-posedness and showing some qualitative results.

Modelling Techniques in Applied Glaciology: Numerical Modelling of Avalanches

1983 ◽  
Vol 4 ◽  
pp. 297-297
Author(s):  
G. Brugnot
Keyword(s):  
Finite Difference Method ◽  
Transverse Velocity ◽  
Longitudinal Velocity ◽  
Momentum Conservation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Modelling Techniques ◽  
Reference Grid ◽  
The One ◽  
Near Future

We consider the paper by Brugnot and Pochat (1981), which describes a one-dimensional model applied to a snow avalanche. The main advance made here is the introduction of the second dimension in the runout zone. Indeed, in the channelled course, we still use the one-dimensional model, but, when the avalanche spreads before stopping, we apply a (x, y) grid on the ground and six equations have to be solved: (1) for the avalanche body, one equation for continuity and two equations for momentum conservation, and (2) at the front, one equation for continuity and two equations for momentum conservation. We suppose the front to be a mobile jump, with longitudinal velocity varying more rapidly than transverse velocity.We solve these equations by a finite difference method. This involves many topological problems, due to the actual position of the front, which is defined by its intersection with the reference grid (SI, YJ). In the near future our two directions of research will be testing the code on actual avalanches and improving it by trying to make it cheaper without impairing its accuracy.

Tilting transitions in a one-dimensional model lipid monolayer

1992 ◽  
Vol 25 (10) ◽  
pp. 2889-2896 ◽  
Author(s):  
R D Gianotti ◽  
M J Grimson ◽  
M Silbert
Keyword(s):  
Lipid Monolayer ◽  
Dimensional Model ◽  
One Dimensional
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