Commit 05d2ab92 authored by andy's avatar andy
Browse files

ENH: Updated liquid evaporation/boiling model in lagrangian intermediate library

parent e0824b96
......@@ -157,8 +157,8 @@ void Foam::LiquidEvaporationBoil<CloudType>::calculate
// liquid volume fraction
const scalarField X(liquids_.X(Yl));
// droplet surface pressure
scalar ps = liquids_.pv(pc, T, X);
// droplet vapour surface pressure
scalar ps = liquids_.pv(pc, Ts, X);
// vapour density at droplet surface [kg/m3]
scalar rhos = ps*liquids_.W(X)/(specie::RR*Ts);
......@@ -178,66 +178,64 @@ 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(pc);
const scalar TBoil = liquids_.properties()[lid].pvInvert(ps);
// 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(pc, Td);
const scalar pSat = liquids_.properties()[lid].pv(ps, Td);
// carrier phase concentration
const scalar Xc = XcMix[gid];
if (Xc*pc > pSat)
{
// saturated vapour - no phase change
}
else
{
// vapour diffusivity [m2/s]
const scalar Dab = liquids_.properties()[lid].D(ps, Td);
// Schmidt number
const scalar Sc = nu/(Dab + ROOTVSMALL);
// Sherwood number
const scalar Sh = this->Sh(Re, Sc);
if (pSat > 0.999*pc)
{
// boiling
// const scalar deltaT = max(Tc - Td, 0.5);
const scalar deltaT = max(Tc - T, 0.5);
const scalar deltaT = max(T - TBoil, 0.5);
// liquid specific heat capacity
const scalar Cp = liquids_.properties()[lid].Cp(pc, Td);
// vapour heat of fomation
// vapour heat of formation
const scalar hv = liquids_.properties()[lid].hl(pc, Td);
// Nusselt number
const scalar Nu = 2.0 + 0.6*sqrt(Re)*cbrt(Pr);
const scalar lg = log(1.0 + Cp*deltaT/max(SMALL, hv));
// mass transfer [kg]
dMassPC[lid] += pi*kappac*Nu*lg*d/Cp*dt;
// NOTE: Using Sherwood number instead of Nusselt number
dMassPC[lid] += pi*kappac*Sh*lg*d/Cp*dt;
}
else
{
// evaporation
// surface molar fraction - Raoult's Law
const scalar Xs = X[lid]*pSat/pc;
const scalar Xs = X[lid]*pSat/ps;
// molar ratio
const scalar Xr = (Xs - Xc)/max(SMALL, 1.0 - Xs);
if (Xr > 0)
{
// vapour diffusivity [m2/s]
const scalar Dab = liquids_.properties()[lid].D(pc, Td);
// Schmidt number
const scalar Sc = nu/(Dab + ROOTVSMALL);
// Sherwood number
const scalar Sh = this->Sh(Re, Sc);
// mass transfer coefficient [m/s]
const scalar kc = Sh*Dab/(d + ROOTVSMALL);
......@@ -261,18 +259,24 @@ Foam::scalar Foam::LiquidEvaporationBoil<CloudType>::dh
{
scalar dh = 0;
scalar TDash = T;
if (liquids_.properties()[idl].pv(p, T) >= 0.999*p)
{
TDash = liquids_.properties()[idl].pvInvert(p);
}
typedef PhaseChangeModel<CloudType> parent;
switch (parent::enthalpyTransfer_)
{
case (parent::etLatentHeat):
{
dh = liquids_.properties()[idl].hl(p, T);
dh = liquids_.properties()[idl].hl(p, TDash);
break;
}
case (parent::etEnthalpyDifference):
{
scalar hc = this->owner().composition().carrier().H(idc, T);
scalar hp = liquids_.properties()[idl].h(p, T);
scalar hc = this->owner().composition().carrier().H(idc, TDash);
scalar hp = liquids_.properties()[idl].h(p, TDash);
dh = hc - hp;
break;
......
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