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EBSILON Professional Components / Components - General and Categories / Renewable / Component 167: Electrolysis Cell
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    Component 167: Electrolysis Cell
    In This Topic

    Component 167: Electrolysis Cell

    Specifications

    Line connections

    1

    Water inlet

    2

    Hydrogen outlet

    3

    Oxygen outlet

    4

    Electric power inlet

    5

    Water purge outlet

    6

    Heating inlet

    7

    Cooling outlet

    8

    Control inlet

    9

    Data outlet

     

    General       User Input Values       Characteristics Lines       Physics Used       Displays       Example

    General

    Component 167 represents an electrolysis cell.

    User Input Values 

    FTYPE

    Flag for the fuel cell electrolyte type:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: O-- transport (SOEC)

    =1: H+ transport (e.g. PEM)

    =2: OH- transport (e.g. AEC)

    CELLAREA

    Cell Area

    NCELLSPERSTACK

    Number of cells per stack

    NSTACKS

    Number of Stacks

    TEMP

    Operating Temperature

    FCURRENT

    Flag for cell current settings:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Use value CURRENT

    =1: Set by port 8 M

    CURRENT

    Cell Current

    FLOSSES

    Flag for electrical losses method:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Use curve CUI and reference fluid concentrations

    =1: Use data for ohmic and activation losses

    AN_H2_REF

    Anode reference H2 molar concentration

    AN_H2O_REF

    Anode reference H2O molar concentration

    CAT_O2_REF

    Cathode reference O2 molar concentration

    CAT_H2O_REF

    Cathode reference H2O molar concentration

    T_REF

    Reference Temperature

    P_REF

    Reference Pressure

    FOHMICLOSSES

    Flag for ohmic losses:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Set conductivities

    =1: Overall definition

    =2: Detailed layer definition

    SIGMA_I

    Ionic coductivity per area

    FSIGMA_I

    Flag for ion conductivity definition:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Sigma=K/T*exp(-Ea/(RT))

    =1: Sigma=K*exp(-Ea/(RT))

    K_SIGMA_I

    Ion conductivity K

    EAR_SIGMA_I

    Ion conductivity Ea/R

    EL_D

    Electrolyte thickness

    EL_FSIGMA_I

    Flag for electrolyte ion conductivity definition:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Sigma=K/T*exp(-Ea/(RT))

    =1: Sigma=K*exp(-Ea/(RT))

    EL_K_SIGMA_I

    Electrolyte ion conductivity K

    EL_EAR_SIGMA_I

    Electrolyte ion conductivity Ea/R

    CAT_D

    Cathode thickness

    CAT_FSIGMA_E

    Flag for cathode electron conductivity definition:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Sigma=K/T*exp(-Ea/(RT))

    =1: Sigma=K*exp(-Ea/(RT))

    CAT_K_SIGMA_E

    Cathode electron conductivity K

    CAT_EAR_SIGMA_E

    Cathode electron conductivity Ea/R

    AN_D

    Anode thickness

    AN_FSIGMA_E

    Flag for anode electron conductivity definition:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Sigma=K/T*exp(-Ea/(RT))

    =1: Sigma=K*exp(-Ea/(RT))

    AN_K_SIGMA_E

    Anode electron conductivity K

    AN_EAR_SIGMA_E

    Anode electron conductivity Ea/R

    IC_D

    Interconnect thickness

    IC_FSIGMA_E

    Flag for interconnect electron conductivity definition:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Sigma=K/T*exp(-Ea/(RT))

    =1: Sigma=K*exp(-Ea/(RT))

    IC_K_SIGMA_E

    Interconnect electron conductivity K

    IC_EAR_SIGMA_E

    Interconnect electron conductivity Ea/R

    FACTLOSS

    Flag for activation losses calculation mode:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: No activation losses

    =1: Butler Volmer equation

    AN_ACT_K

    Anode K [Jref=yH2*yH2O*K*exp(-Ea/(R*T))]

    AN_ACT_EA

    Anode Ea [Jref=yH2*yH2O*K*exp(-Ea/(R*T))]

    CAT_ACT_K

    Cathode K [Jref=pow(yO2,0.25)*K*exp(-Ea/(R*T))]

    CAT_ACT_EA

    Cathode Ea [Jref=pow(yO2,0.25)*K*exp(-Ea/(R*T))]

    CDRAGH2O

    Electro-osmotic net drag coefficient (nH2O/nH+) (PEM only)

    FXOH2

    Flag for H2 Crossover calculation:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Use Value XOH2

    =1: Use charline CXOH2

    =2: Use expression EXOH2

    XOH2

    Crossover Fraction H2 from total H2 produced

    EXOH2

    Expression for Crossover Fraction H2

    FXOO2

    Flag for O2 Crossover calculation:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: Use Value XOO2

    =1: Use charline CXOO2

    =2: Use expression EXOO2

    XOO2

    Crossover Fraction O2 from total O2 produced

    EXOO2

    Expression for Crossover Fraction HO

    FDEGRADATION

    flag for degradation Mode:

    Like in Parent Profile (Sub profile option only)

    Expression

    =0: No degradation

    =1: Use Value AREAFRACTION

    =2: Use charline CDEGRADATION

    =3: Use expression EAREAFRACTION

    AREAFRACTION

    Active Area Fraction

    EOHOURS

    Equivalent Operating Hours

    EAREAFRACTION

    Expression for active area fraction

    The parameters marked in blue are reference quantities for the off-design mode. These are calculated and entered here during the design calculation of EBSILON®Professional.

    Generally, all inputs that are visible are required. But, often default values are provided.

    For more information on colour of the input fields and their descriptions see Edit Component\Specification values

    For more information on design vs. off-design and nominal values see General\Accept Nominal values

    Characteristics Lines

    NAME

    X

    Y

    CUI

    Current density

    Voltage

    CDEGRADATION

    Equivalent operating hours

    Active area fraction

    CXOH2

    Current density

    H2 Crossover fraction

    CXOO2

    Current density

    O2 Crossover fraction

     

    Result values

     

    PEL

    Electrical Power

    U

    Voltage

    I

    Current

    ENERGYCON

    Specific energy consumtion per kg H2

    AREA

    Total area

    ADEGRAD

    Effectve area degradation

    AREA_EFF

    Effectve area

    NCELLS

    Total number of cells

    PELCELL

    Cell power

    UCELL

    Cell voltage

    ICELL

    Cell current

    JCELL

    Cell current density (also on Port 9 H)

    SIGMA_I_CELL

    Ionic coductivity per area

     

    Physics Used

    Thermodynamic model

    The thermodynamic model is similar to the fuel cell (Component 163) in the reverse direction. The model is is zero-dimensional, i.e. there is no temperature profile or concentration profile between inlet and outlet. The temperature is considered to be constant and for the concentrations an average between inlet and outlet is taken.

    The model allows different level of details for the current-voltage characteristic of the stack:

    - user defined curve

    - set the overall conductivity for 1/R1

    - set temperature dependent overall conductivity for 1/R1

    - set temperature dependent conductivites for each layer and calculate R1

    Emax will be calculated with the Nernst-equation. For the reaction

    (Ox) a A + b B + ... <=> c C + d D + ... (Red)

    the potential E for a temperature T can be calculated by

    Emax(T) = E0 - (RT)/(zF)*ln((aCc*aDd)/(aAa*aBb))

    E0 = ΔG0/(RT)

    R1 Overall ohmic losses
    A, B, C, D Component A,B,C,D in the reaction
    a,b,c,d Stoechiometric coefficients of the components in reaction
    E0 reference potential
    Emax(T) Current potential at temperature T for given activities of A,B,C,D
    aA, aB, aC, aD activities of components A,B,C,D
    ΔG0 Gibbs free energy of the reaction at reference conditions (activity=1, p=pref)
    z electrons taking part in the redox reaction
    F Faraday constant
    R Gas constant
    T Temperature

    Losses

    If FLOSSES is set to curve mode, all losses are derived directly from the curve. for a given current density a curve lookup will be made and via the Nernst-equation, Emax for the reference fluid is calculated. The difference is considered as the losses to apply at current conditions

    In non-curve mode, Emax will be reduced by ohmic-losses, activation-losses and crossover-losses, if desired

    The activation losses will be calculated by the Butler-Volmer-equation for the anode and cathode side.

    The ohmic lossses will be calculated according to the setting of FOHMICLOSSES. If temperature dependent behavior is selected, an arrhenius formulation for the conductivity is used.

    The crossover lossses allow modeling the migration of H2 and O2 over the electrolyte. Additionally for PEM a water drag coefficient can be specified, which allows to model the migration of water in the electric field over the electrolyte.

    Degradation

    Degradation is modeled by reducing the active stack area, which results in an increase of current density and therefore an increase of the losses. The reduction of the active area is modeled with a characteristic curve CDEGRADATION which models equivalent operating hours vs. active area fraction

    Equations

    H4 = Pel

    Electrical Power

    P4 = U

    Voltage

    M4 = 0

    DC

    P1 = P2 = P3 = P5

    M5 = m_purge

    purge

    M1 - M2 = m_O2

    H2 production (SOFC type only)

    M3 - M2 = m_O2 - (m_H2+m_excess)

    O2 production balance
    m_excess = m_feed - m_H2 - m_O2 (m_excess >= 0)

    M2 = m_H2

    H2 production (PEM and OH- types only)

    M1 = m_H2 + m_O2 + m_purge

    Water feed (PEM and OH- types only)

    Literature references

    Kurzweil, Dietlmeier, Elektrochemische Speicher, Springer Vieweg (2018)

    Component Displays

    Display Option 1: Electrolysis Cell

    Display Option 2: Electrolysis Cell

    Example

    Click here >> Component 167 Demo << to load an example.

     

     

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