growthModel_HACA.cc

Go to the documentation of this file.

#include "growthModels/growthModel_HACA.h"
#include "sootDefs.h"
#include "sootModel.h"          // for the SM back pointer
 
using namespace std;
using namespace soot;
 
 
growthModel_HACA::growthModel_HACA() {
 
    growthRxnRatios[(int)gasSp::O2]   =  0;
    growthRxnRatios[(int)gasSp::OH]   = -1;
    growthRxnRatios[(int)gasSp::H]    = -1;
    growthRxnRatios[(int)gasSp::H2]   =  1;
    growthRxnRatios[(int)gasSp::H2O]  =  1;
    growthRxnRatios[(int)gasSp::C2H2] = -1;
    growthRxnRatios[(int)gasSp::CO]   =  0;
    growthRxnRatios[(int)gasSp::C]    =  2;
 
    mechType = growthMech::HACA;
}
 
 
double growthModel_HACA::getGrowthSootRate(const state& state) const {
 
    double M0 = state.sootVar[0];                           // #/m3
    double M1 = state.sootVar[1];                           // kg/m3
 
    if (SM->psdMechType == psdMech::SECT) {
        M0 = 0.0;
        M1 = 0.0;
        for (size_t k=0; k<state.nsoot; k++) {
            M0 += state.sootVar[k];
            M1 += state.sootVar[k]*SM->mBins[k];
        }
    }
 
    //---------- calculate alpha, other constants
 
    double RT = 1.9872036E-3 * state.T;                 // R (=) kcal/mol
    double chi_CH  = 2.3E15;                            // C-H sites/cm^2
    double a_param = 33.167 - 0.0154 * state.T;         // a parameter for calculating alpha
    double b_param = -2.5786 + 0.00112 * state.T;       // b parameter for calculating alpha
 
    //---------- calculate raw HACA reaction rates
 
    double fR1 = 4.2E13 * exp(-13.0 / RT) * state.getGasSpC(gasSp::H) / 1000;
    double rR1 = 3.9E12 * exp(-11.0 / RT) * state.getGasSpC(gasSp::H2) / 1000;
    double fR2 = 1.0E10 * pow(state.T, 0.734) * exp(-1.43 / RT) * state.getGasSpC(gasSp::OH) / 1000;
    double rR2 = 3.68E8 * pow(state.T, 1.139) * exp(-17.1 / RT) * state.getGasSpC(gasSp::H2O) / 1000;
    double fR3 = 2.0E13 * state.getGasSpC(gasSp::H) / 1000;
    double fR4 = 8.00E7 * pow(state.T, 1.56) * exp(-3.8 / RT) * state.getGasSpC(gasSp::C2H2) / 1000;
    double fR5 = 2.2E12 * exp(-7.5 / RT) * state.getGasSpC(gasSp::O2) / 1000;
 
    //---------- Steady state calculation of chi for soot radical; see Frenklach 1990 pg. 1561
 
    double denom = rR1 + rR2 + fR3 + fR4 + fR5;
    double chi_S = denom == 0 ? 0 : 2 * chi_CH * (fR1 + fR2) / denom;  // C-* sites/cm^2
 
    double alpha = 1.0;
    if (M0 > 0)
        alpha = tanh(a_param/log10(M1/M0) + b_param);                     // alpha = fraction of available surface sites
    if (alpha < 0) alpha=1.0;
 
    double rxns_s = fR4*alpha*chi_S * 1E4;        // reactions at sites per m2 per s.
    return 2.0*rxns_s*gasSpMW[(int)gasSp::C]/Na;  // kg/m2/s: each site: 2.0: each site gets 2 Carbons
}