/*---------------------------------------------------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | \\ / A nd | www.openfoam.com \\/ M anipulation | ------------------------------------------------------------------------------- Copyright (C) 2011-2016 OpenFOAM Foundation Copyright (C) 2020 OpenCFD Ltd. ------------------------------------------------------------------------------- License This file is part of OpenFOAM. OpenFOAM is free software: you can redistribute it and/or modify it 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 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenFOAM. If not, see . \*---------------------------------------------------------------------------*/ #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); } // ************************************************************************* //