/*---------------------------------------------------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration |
\\ / A nd | www.openfoam.com
\\/ M anipulation |
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Copyright (C) 2011-2016 OpenFOAM Foundation
Copyright (C) 2020 OpenCFD Ltd.
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License
This file is part of OpenFOAM.
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under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
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for more details.
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\*---------------------------------------------------------------------------*/
#include "LiquidEvaporationBoil.H"
#include "specie.H"
#include "mathematicalConstants.H"
using namespace Foam::constant::mathematical;
// * * * * * * * * * * * * Protected Member Functions * * * * * * * * * * * //
template
Foam::tmp Foam::LiquidEvaporationBoil::calcXc
(
const label celli
) const
{
scalarField Xc(this->owner().thermo().carrier().Y().size());
forAll(Xc, i)
{
Xc[i] =
this->owner().thermo().carrier().Y()[i][celli]
/this->owner().thermo().carrier().W(i);
}
return Xc/sum(Xc);
}
template
Foam::scalar Foam::LiquidEvaporationBoil::Sh
(
const scalar Re,
const scalar Sc
) const
{
return 2.0 + 0.6*Foam::sqrt(Re)*cbrt(Sc);
}
// * * * * * * * * * * * * * * * * Constructors * * * * * * * * * * * * * * //
template
Foam::LiquidEvaporationBoil::LiquidEvaporationBoil
(
const dictionary& dict,
CloudType& owner
)
:
PhaseChangeModel(dict, owner, typeName),
liquids_(owner.thermo().liquids()),
activeLiquids_(this->coeffDict().lookup("activeLiquids")),
liqToCarrierMap_(activeLiquids_.size(), -1),
liqToLiqMap_(activeLiquids_.size(), -1)
{
if (activeLiquids_.size() == 0)
{
WarningInFunction
<< "Evaporation model selected, but no active liquids defined"
<< nl << endl;
}
else
{
Info<< "Participating liquid species:" << endl;
// Determine mapping between liquid and carrier phase species
forAll(activeLiquids_, i)
{
Info<< " " << activeLiquids_[i] << endl;
liqToCarrierMap_[i] =
owner.composition().carrierId(activeLiquids_[i]);
}
// Determine mapping between model active liquids and global liquids
const label idLiquid = owner.composition().idLiquid();
forAll(activeLiquids_, i)
{
liqToLiqMap_[i] =
owner.composition().localId(idLiquid, activeLiquids_[i]);
}
}
}
template
Foam::LiquidEvaporationBoil::LiquidEvaporationBoil
(
const LiquidEvaporationBoil& pcm
)
:
PhaseChangeModel(pcm),
liquids_(pcm.owner().thermo().liquids()),
activeLiquids_(pcm.activeLiquids_),
liqToCarrierMap_(pcm.liqToCarrierMap_),
liqToLiqMap_(pcm.liqToLiqMap_)
{}
// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
template
Foam::LiquidEvaporationBoil::~LiquidEvaporationBoil()
{}
// * * * * * * * * * * * * * * * Member Functions * * * * * * * * * * * * * //
template
void Foam::LiquidEvaporationBoil::calculate
(
const scalar dt,
const label celli,
const scalar Re,
const scalar Pr,
const scalar d,
const scalar nu,
const scalar rho,
const scalar T,
const scalar Ts,
const scalar pc,
const scalar Tc,
const scalarField& X,
const scalarField& solMass,
const scalarField& liqMass,
scalarField& dMassPC
) const
{
// immediately evaporate mass that has reached critical condition
if ((liquids_.Tc(X) - T) < SMALL)
{
if (debug)
{
WarningInFunction
<< "Parcel reached critical conditions: "
<< "evaporating all available mass" << endl;
}
forAll(activeLiquids_, i)
{
const label lid = liqToLiqMap_[i];
dMassPC[lid] = GREAT;
}
return;
}
// 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)/(RR*Ts);
// construct carrier phase species volume fractions for cell, celli
const scalarField XcMix(calcXc(celli));
// carrier thermo properties
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().Ha(i, pc, Tc);
Hsc += Yc*this->owner().thermo().carrier().Ha(i, ps, Ts);
Cpc += Yc*this->owner().thermo().carrier().Cp(i, ps, Ts);
kappac += Yc*this->owner().thermo().carrier().kappa(i, ps, Ts);
}
// calculate mass transfer of each specie in liquid
forAll(activeLiquids_, i)
{
const label gid = liqToCarrierMap_[i];
const label lid = liqToLiqMap_[i];
// boiling temperature at cell pressure for liquid species lid [K]
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(pc, 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, Ts);
// 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(T - TBoil, 0.5);
// vapour heat of formation
const scalar hv = liquids_.properties()[lid].hl(pc, Td);
// 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;
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/pc;
// molar ratio
const scalar Xr = (Xs - Xc)/max(SMALL, 1.0 - Xs);
if (Xr > 0)
{
// mass transfer [kg]
dMassPC[lid] += pi*d*Sh*Dab*rhos*log(1.0 + Xr)*dt;
}
}
}
}
}
template
Foam::scalar Foam::LiquidEvaporationBoil::dh
(
const label idc,
const label idl,
const scalar p,
const scalar T
) const
{
scalar dh = 0;
scalar TDash = T;
if (liquids_.properties()[idl].pv(p, T) >= 0.999*p)
{
TDash = liquids_.properties()[idl].pvInvert(p);
}
typedef PhaseChangeModel parent;
switch (parent::enthalpyTransfer_)
{
case (parent::etLatentHeat):
{
dh = liquids_.properties()[idl].hl(p, TDash);
break;
}
case (parent::etEnthalpyDifference):
{
scalar hc = this->owner().composition().carrier().Ha(idc, p, TDash);
scalar hp = liquids_.properties()[idl].h(p, TDash);
dh = hc - hp;
break;
}
default:
{
FatalErrorInFunction
<< "Unknown enthalpyTransfer type" << abort(FatalError);
}
}
return dh;
}
template
Foam::scalar Foam::LiquidEvaporationBoil::Tvap
(
const scalarField& X
) const
{
return liquids_.Tpt(X);
}
template
Foam::scalar Foam::LiquidEvaporationBoil::TMax
(
const scalar p,
const scalarField& X
) const
{
return liquids_.pvInvert(p, X);
}
// ************************************************************************* //