diff --git a/src/lagrangian/intermediate/submodels/Reacting/PhaseChangeModel/LiquidEvaporationBoil/LiquidEvaporationBoil.C b/src/lagrangian/intermediate/submodels/Reacting/PhaseChangeModel/LiquidEvaporationBoil/LiquidEvaporationBoil.C
index ced9a982216ff9503944d46a73ddd91fe1c4279e..9887cf3897341ee8d60182e42f18d7b37e44c311 100644
--- a/src/lagrangian/intermediate/submodels/Reacting/PhaseChangeModel/LiquidEvaporationBoil/LiquidEvaporationBoil.C
+++ b/src/lagrangian/intermediate/submodels/Reacting/PhaseChangeModel/LiquidEvaporationBoil/LiquidEvaporationBoil.C
@@ -157,19 +157,12 @@ void Foam::LiquidEvaporationBoil<CloudType>::calculate
// liquid volume fraction
const scalarField X(liquids_.X(Yl));
- // droplet vapour surface pressure
+ // droplet surface pressure assumed to surface vapour pressure
scalar ps = liquids_.pv(pc, Ts, X);
// vapour density at droplet surface [kg/m3]
scalar rhos = ps*liquids_.W(X)/(specie::RR*Ts);
- // thermal conductivity of carrier [W/m/K]
- scalar kappac = 0.0;
- forAll(this->owner().thermo().carrier().Y(), i)
- {
- const scalar Yc = this->owner().thermo().carrier().Y()[i][cellI];
- kappac += Yc*this->owner().thermo().carrier().kappa(i, Ts);
- }
// calculate mass transfer of each specie in liquid
forAll(activeLiquids_, i)
@@ -178,13 +171,13 @@ void Foam::LiquidEvaporationBoil<CloudType>::calculate
const label lid = liqToLiqMap_[i];
// boiling temperature at cell pressure for liquid species lid [K]
- const scalar TBoil = liquids_.properties()[lid].pvInvert(ps);
+ const scalar TBoil = liquids_.properties()[lid].pvInvert(pc);
// limit droplet temperature to boiling/critical temperature
const scalar Td = min(T, 0.999*TBoil);
// saturation pressure for liquid species lid [Pa]
- const scalar pSat = liquids_.properties()[lid].pv(ps, Td);
+ const scalar pSat = liquids_.properties()[lid].pv(pc, Td);
// carrier phase concentration
const scalar Xc = XcMix[gid];
@@ -197,7 +190,7 @@ void Foam::LiquidEvaporationBoil<CloudType>::calculate
else
{
// vapour diffusivity [m2/s]
- const scalar Dab = liquids_.properties()[lid].D(ps, Td);
+ const scalar Dab = liquids_.properties()[lid].D(ps, Ts);
// Schmidt number
const scalar Sc = nu/(Dab + ROOTVSMALL);
@@ -212,35 +205,82 @@ void Foam::LiquidEvaporationBoil<CloudType>::calculate
const scalar deltaT = max(T - TBoil, 0.5);
- // liquid specific heat capacity
- const scalar Cp = liquids_.properties()[lid].Cp(pc, Td);
+ scalar Hsc = 0.0;
+ scalar Hc = 0.0;
+ scalar Cpc = 0.0;
+ scalar kappac = 0.0;
+ forAll(this->owner().thermo().carrier().Y(), i)
+ {
+ scalar Yc = this->owner().thermo().carrier().Y()[i][cellI];
+ Hc += Yc*this->owner().thermo().carrier().H(i, Tc);
+ Hsc += Yc*this->owner().thermo().carrier().H(i, Ts);
+ Cpc += Yc*this->owner().thermo().carrier().Cp(i, Ts);
+ kappac += Yc*this->owner().thermo().carrier().kappa(i, Ts);
+ }
// vapour heat of formation
const scalar hv = liquids_.properties()[lid].hl(pc, Td);
- const scalar lg = log(1.0 + Cp*deltaT/max(SMALL, hv));
+ // empirical heat transfer coefficient W/m2/K
+ scalar alphaS = 0.0;
+ if (deltaT < 5.0)
+ {
+ alphaS = 760.0*pow(deltaT, 0.26);
+ }
+ else if (deltaT < 25.0)
+ {
+ alphaS = 27.0*pow(deltaT, 2.33);
+ }
+ else
+ {
+ alphaS = 13800.0*pow(deltaT, 0.39);
+ }
+
+ // flash-boil vaporisation rate
+ const scalar Gf = alphaS*deltaT*pi*sqr(d)/hv;
+
+ // model constants
+ // NOTE: using Sherwood number instead of Nusselt number
+ const scalar A = (Hc - Hsc)/hv;
+ const scalar B = pi*kappac/Cpc*d*Sh;
- // mass transfer [kg]
- // NOTE: Using Sherwood number instead of Nusselt number
- dMassPC[lid] += pi*kappac*Sh*lg*d/Cp*dt;
+ scalar G = 0.0;
+ if (A > 0.0)
+ {
+ // heat transfer from the surroundings contributes
+ // to the vaporisation process
+ scalar Gr = 1e-5;
+
+ for (label i=0; i<50; i++)
+ {
+ scalar GrDash = Gr;
+
+ G = B/(1.0 + Gr)*log(1.0 + A*(1.0 + Gr));
+ Gr = Gf/G;
+
+ if (mag(Gr - GrDash)/GrDash < 1e-3)
+ {
+ break;
+ }
+ }
+ }
+
+ dMassPC[lid] += (G + Gf)*dt;
}
else
{
// evaporation
// surface molar fraction - Raoult's Law
- const scalar Xs = X[lid]*pSat/ps;
+ const scalar Xs = X[lid]*pSat/pc;
// molar ratio
const scalar Xr = (Xs - Xc)/max(SMALL, 1.0 - Xs);
if (Xr > 0)
{
- // mass transfer coefficient [m/s]
- const scalar kc = Sh*Dab/(d + ROOTVSMALL);
-
// mass transfer [kg]
- dMassPC[lid] += pi*sqr(d)*kc*rhos*log(1.0 + Xr)*dt;
+ dMassPC[lid] += pi*d*Sh*Dab*rhos*log(1.0 + Xr)*dt;
}
}
}
@@ -291,7 +331,7 @@ Foam::scalar Foam::LiquidEvaporationBoil<CloudType>::dh
"const label, "
"const label, "
"const label"
- ")"
+ ") const"
) << "Unknown enthalpyTransfer type" << abort(FatalError);
}
}
diff --git a/src/lagrangian/intermediate/submodels/Reacting/PhaseChangeModel/LiquidEvaporationBoil/LiquidEvaporationBoil.H b/src/lagrangian/intermediate/submodels/Reacting/PhaseChangeModel/LiquidEvaporationBoil/LiquidEvaporationBoil.H
index f16ea47be91521cc2e3b108e4aa7293884096b6a..48d92292cdcd890a46699dc9f7847651512eaf1b 100644
--- a/src/lagrangian/intermediate/submodels/Reacting/PhaseChangeModel/LiquidEvaporationBoil/LiquidEvaporationBoil.H
+++ b/src/lagrangian/intermediate/submodels/Reacting/PhaseChangeModel/LiquidEvaporationBoil/LiquidEvaporationBoil.H
@@ -27,7 +27,16 @@ Class
Description
Liquid evaporation model
- uses ideal gas assumption
- - includes boiling model
+ - includes boiling model based on:
+
+ \verbatim
+ "Studies of Superheated Fuel Spray Structures and Vaporization in
+ GDI Engines"
+
+ Zuo, B., Gomes, A. M. and Rutland C. J.
+
+ International Journal of Engine Research, 2000, Vol. 1(4), pp. 321-336
+ \endverbatim
\*---------------------------------------------------------------------------*/