FCSys.Regions.AnFPs

Anode flow plates

Information

Extends from Modelica.Icons.Package (Icon for standard packages).

Package Content

Name	Description
AnFP	Anode flow plate

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FCSys.Regions.AnFPs.AnFP

Anode flow plate

Information

This model represents the anode flow plate of a PEMFC. The x axis extends from the anode to the cathode. Fluid is considered to travel in the y direction, with the associated length factor (k_y) greater than one (by default) to represent a serpentine channel. The model is bidirectional, meaning that either yNegative or yPositive can be used as the inlet. By default, the cross-sectional area in the yz plane is 50 cm².

The solid and the fluid phases are assumed to exist in the same subregions, even though a typical flow plate is impermeable to the fluid (except for the channel). In theory, it is possible to discretize the flow plate into smaller subregions for the bulk solid, lands, and valleys. However, this would significantly increase the mathematical size of the model. Currently, that level of detail is best left to computational fluid dynamics.

The x component of the transport factor (k_x) for the gas and the liquid should generally be less than one because the transport distance into/out of the GDL is less that half the thickness of the flow plate. It is equal to the product of two ratios:

1. the depth of the channels to the thickness of the flow plate
2. the product of the total area of the flow plate in the yz plane (land + valleys) and the fraction of the total volume available for the fluid (ε) to the area of the valleys in the yz plane

See Species.'C+'.Graphite.Fixed regarding the default specific heat capacity. The default thermal resistivity of the carbon (θ = U.m*U.K/(95*U.W)) and the electrical conductivity (σ = U.S/(1.470e-3*U.cm)) are that of Entegris/Poco Graphite AXF-5Q [Entegris2012]. There is additional data in the text layer of this model.

For more information, please see the Region model.

Extends from Region (Base model for a 3D array of subregions).

Parameters

Type	Name	Default	Description
replaceable model Subregion		FCSys.Subregions.SubregionNo…	Base subregion model
Length	D	0.937*U.mm	Hydraulic diameter of the channel [L]
Length	L_channel	162.4*U.cm	Length of the channel [L]
Geometry
Length	L_x[:]	{10}*U.mm	Lengths along the x axis [L]
Length	L_y[:]	{8}*U.cm	Lengths along the y axis [L]
Length	L_z[:]	{6.25}*U.cm	Lengths across the z axis [L]
NumberAbsolute	epsilon	0.0588	Fraction of volume for the fluid [1]
Assumptions
Included transport axes
Boolean	inclTransX	true	X
Boolean	inclTransY	true	Y
Boolean	inclTransZ	false	Z

Connectors

Type	Name	Description
replaceable model Subregion		Base subregion model
BoundaryBus	xNegative[n_y, n_z]	Negative boundary along the x axis
BoundaryBus	xPositive[n_y, n_z]	Positive boundary along the x axis
BoundaryBus	yNegative[n_x, n_z]	Negative boundary along the y axis
BoundaryBus	yPositive[n_x, n_z]	Positive boundary along the y axis
BoundaryBus	zNegative[n_x, n_y]	Negative boundary along the z axis
BoundaryBus	zPositive[n_x, n_y]	Positive boundary along the z axis

Modelica definition

model AnFP "Anode flow plate"
  import Modelica.Constants.inf;
  // extends FCSys.Icons.Names.Top4;

  extends Region(
    L_x={10}*U.mm,
    L_y={8}*U.cm,
    L_z={6.25}*U.cm,
    final inclTransX=true,
    final inclTransY=true,
    inclTransZ=false,
    redeclare replaceable model Subregion = FCSys.Subregions.SubregionNoIonomer
        (
        common(k_Phi={1e7,inf,1e7},k_Q=1e5),
        gas(
          common(k_Phi={inf,inf,inf}),
          H2_H2O(k_Phi={inf,inf,inf}),
          k={0.22*epsilon,Lstar/n_y,n_y/Lstar},
          inclH2=true,
          inclH2O=true,
          H2(
            upstreamX=false,
            Nu_Phi={4,16*A[Axis.z]*epsilon/D^2,4},
            final zeta=0,
            T(stateSelect=StateSelect.always)),
          H2O(
            upstreamX=false,
            Nu_Phi={4,16*A[Axis.z]*epsilon/D^2,4},
            final zeta=0,
            I(each stateSelect=StateSelect.always, each fixed=true),
            initEnergy=Init.none)),
        graphite(
          'inclC+'=true,
          'incle-'=true,
          'C+'(theta=U.m*U.K/(95*U.W),epsilon=1 - epsilon),
          'e-'(sigma=U.S/(1.470e-3*U.cm))),
        liquid(
          k={0.22*epsilon,Lstar/n_y,n_y/Lstar},
          inclH2O=true,
          H2O(
            upstreamX=false,
            Nu_Phi={4,16*A[Axis.z]*epsilon/D^2,4},
            epsilon_IC=1e-5,
            N0=0.1*U.C))));

  parameter Q.NumberAbsolute epsilon(nominal=1) = 0.0588 
    "Fraction of volume for the fluid";

  parameter Q.Length D=0.937*U.mm "Hydraulic diameter of the channel";

  parameter Q.Length L_channel=162.4*U.cm "Length of the channel";

protected 
  final parameter Q.NumberAbsolute Lstar=L_channel/L[Axis.y] 
    "Ratio of the length of the channel to the length of the layer in the y direction";

  Q.Velocity phi_states_H2[:, :, :](
    each stateSelect=StateSelect.always,
    each start=0,
    each fixed=true) = subregions[:, 2:n_y, :].gas.H2.phi[2] if n_y > 1 
    "Forced states for H2";
  // Note:  This avoids dynamic state selection in Dymola 2014.

  outer Conditions.Environment environment "Environmental conditions";

  // Thermal resistivity of some other flow plate materials [Incropera2002, pp. 905 & 907]:
  //                                Stainless steel
  //                                ---------------------------------------------------------------------------------
  //             Aluminium (pure)   AISI 302             AISI 304              AISI 316              AISI 347
  //             ----------------   ------------------   ------------------    -----------------    -----------------
  //                        theta              theta                theta                 theta                theta
  //             c_p*U.kg   *U.W    c_p*U.kg   *U.W      c_p*U.kg   *U.W       c_p*U.kg   *U.W      c_p*U.kg   *U.W
  //             *U.K       /(U.m   *U.K       /(U.m     *U.K       /(U.m      *U.K       /(U.m     *U.K       /(U.m
  //     T/K     /(U.J*m)   *U.K)   /(U.J*m)   *U.K)     /(U.J*m)   *U.K)      /(U.J*m)   *U.K)     /(U.J*m)   *U.K)
  //     ----    --------   -----   --------   ------    --------   -------    --------   ------    --------   ------
  //     100     482        1/302                        272        1/9.2
  //     200     798        1/237                        402        1/12.6
  //     300     903        1/237   480        1/15.1    477        1/14.9     468        1/13.4    480        1/14.2
  //     400     949        1/240   512        1/17.3    515        1/16.6     504        1/15.2    513        1/15.8
  //     600     1033       1/231   559        1/20.0    557        1/19.8     550        1/18.3    559        1/18.9
  //     800     1146       1/218   585        1/22.8    582        1/22.6     576        1/21.3    585        1/21.9
  //     1000                       606        1/25.4    611        1/25.4     602        1/24.2    606        1/24.7

  // Electrical resistivities:
  //     Aluminium
  //     (http://en.wikipedia.org/wiki/Electrical_resistivity, 2008):
  //         2.82e-8 ohm.m
  //     Graphite (http://hypertextbook.com/facts/2004/AfricaBelgrave.shtml):
  //         7.837e-6 to 41e-6 ohm.m
  //     Copper (http://en.wikipedia.org/wiki/Electrical_resistivity, 2008):
  //         1.72e-8 ohm.m
  //     Stainless steel AISI 304
  //     (http://hypertextbook.com/facts/2006/UmranUgur.shtml, 2008):
  //         6.897e-7 ohm.m

end AnFP;