DCO2 1.96e-9[m^2/s] "Diffusion coefficient of CO2"
DH2CO3 2e-9[m^2/s] "Diffusion coefficient of H2CO3"
DHCO3 1.105e-9[m^2/s] "Diffusion coefficient of HCO3"
DH 9.312e-9[m^2/s] "Diffusion coefficient of H"
DOH 5.26e-9[m^2/s] "Diffusion coefficient of OH"
DFe 0.72e-9[m^2/s] "Diffusion coefficient of Fe"
T 20[degC] "Operating temperature"
T_init 20[degC] "Initial operating temperature"
TF (T-0[degC])/1[K]*1.8+32 "Operating temperature in Fahrenheit"
TF_init (T_init-0[degC])/1[K]*1.8+32 "Initial temperature in Fahrenheit"
PCO2 1 "Partial pressure of CO2 in bar"
PCO2_init 1 "Initial partial pressure of CO2 in bar"
KCO2 0.0454*(1.6616-5.736e-2*(T[1/K]-273)+1.031e-3*(T[1/K]-273)^2-9.68e-6*(T[1/K]-273)^3+4.471e-8*(T[1/K]-273)^4-7.912e-11*(T[1/K]-273)^5) "Henry's constant"
KCO2_init 0.0454*(1.6616-5.736e-2*(T_init[1/K]-273)+1.031e-3*(T_init[1/K]-273)^2-9.68e-6*(T_init[1/K]-273)^3+4.471e-8*(T_init[1/K]-273)^4-7.912e-11*(T_init[1/K]-273)^5) "Henry's constant at initial operating temperature"
KCO2H 2.58e-3 "Equilibrium constant for CO2 hydration"
KH2CO3 387.6*10^(-(6.41-1.594e-3*TF+8.52e-6*(TF)^2)) "Equilibrium constant for H2CO3 dissociation"
KH2CO3_init 387.6*10^(-(6.41-1.594e-3*TF_init+8.52e-6*(TF_init)^2)) "Equilibrium constant for H2CO3 dissociation at initial temperature"
KHCO3 10^(-(10.61-4.97e-3*TF+1.331e-5*(TF)^2)) "Equilibrium constant for HCO3 dissociation"
kCO2H 10^(169.2-53*log10(T[1/K])-11715/T[1/K])[1/s] "Forward reaction rate for CO2 hydration"
c_unit 1000[mol/m^3] "Unit activity concentration"
cCO20 KCO2*PCO2*1e3[mol/m^3] "Bulk concentration of CO2"
cCO2_init KCO2_init*PCO2_init*1e3[mol/m^3] "Initial concentration of CO2"
cH2CO30 KCO2H*cCO20 "Bulk concentration of H2CO3"
cH2CO3_init KCO2H*cCO2_init "Initial concentration of H2CO3"
cHCO30 sqrt(KH2CO3*c_unit*cH2CO30) "Bulk concentration of HCO3-"
cHCO3_init sqrt(KH2CO3_init*c_unit*cH2CO3_init) "Initial concentration of HCO3-"
cFe0 0[mol/m^3] "Initial concentration of Fe++"
phil0 0.5[V] "Initial electrolyte potential"
delta 50[um] "Boundary layer thickness"
rho_steel 7850[kg/m^3] "Density of steel"
Mw_steel 55.845[g/mol] "Molecular weight of steel"
b_H2 0.118[V] "Tafel slope for H+ reduction"
b_Fe 0.04[V] "Tafel slope for Fe oxidation"
TrefFe 25[degC] "Reference temperature"
TrefH2 25[degC] "Reference temperature"
alphaa_Fe log(10)*R_const*T/(b_Fe*F_const) "Anodic transfer coefficient for iron dissolution"
alphaa_H2 1-log(10)*R_const*T/(b_H2*F_const) "Anodic transfer coefficient for hydrogen evolution"
Eeq_ref_Fe -0.409[V] "Reference equilibrium potential for iron dissolution"
Eeq_ref_H2 0[V] "Reference equilibrium potential for hydrogen evolution"
i0_ref_Fe 1[A/m^2]*exp(-37.5e3[J/mol]/R_const*(1/T-1/TrefFe)) "Reference exchange current density for iron dissolution"
i0_ref_H2 1[A/m^2]*exp(-30e3[J/mol]/R_const*(1/T-1/TrefH2)) "Reference exchange current density for hydrogen evolution"