.FuelCellLib.Basics.tp_dif

Information

tp_dif-Transport Phenomena

The following eq, shows the flux of gases depending of two phenomena: Stefan-Maxwell diffusion, and Knudsen diffusion.

The following eqs., shows the expression of binary diffusion coeffient and Knudsen diffusion coefficient equations. This is variable modeling hypothesis, and it could be simulated as a constant or a dependence on pore size equation.

The maximum water load in diffusion layer is shown next and it depends on the density of water and the solid and the volume of solid.

The pore volume is the blank space that doesn't fill of liquid water and solid volume.

This equation shown the flux of liquid water as a dependence on the gradient of water load.

The electronic current is shown like a ohm?s law. Ks parameter is the electronic conductivity of the solid.

Parameters

Name Default Description

tau Tortuosity

Es Volumetric fraction of solid

da Thickness of transport phenomena [m]

T Operation temperature of active layer [K]

Dwl Surface diffusion coefficient of H2O, liquid phase [m2/s]

ks Electrical conducivity of the solid [S/m]

kp Constant protonic conducivity of the electrolyte [S/m]

ros Density of the solid [kg/m3]

roh2ol Density of water [kg/m3]

D1co Constant Knudsen diffusion coefficient for oxygen [m2/s]

D2co Constant Knudsen diffusion coefficient for steam water [m2/s]

rp Pore size of porous media [m]

D12o Constant binary diffusion coefficient [m2/s]

pAref Reference pressure to measure the binary diffusion coefficient [Pa]

Tref Reference temperature to measure the binary diffusion coefficient [K]

ModHyp2 Knudsen diffusion pore size dependence(0:Off,1:On)

Name	Default	Description
tau		Tortuosity
Es		Volumetric fraction of solid
da		Thickness of transport phenomena [m]
T		Operation temperature of active layer [K]
Dwl		Surface diffusion coefficient of H2O, liquid phase [m2/s]
ks		Electrical conducivity of the solid [S/m]
kp		Constant protonic conducivity of the electrolyte [S/m]
ros		Density of the solid [kg/m3]
roh2ol		Density of water [kg/m3]
D1co		Constant Knudsen diffusion coefficient for oxygen [m2/s]
D2co		Constant Knudsen diffusion coefficient for steam water [m2/s]
rp		Pore size of porous media [m]
D12o		Constant binary diffusion coefficient [m2/s]
pAref		Reference pressure to measure the binary diffusion coefficient [Pa]
Tref		Reference temperature to measure the binary diffusion coefficient [K]
ModHyp2		Knudsen diffusion pore size dependence(0:Off,1:On)

References

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