PengRobinsonParamsMixture.hpp

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// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
/*
  This file is part of the Open Porous Media project (OPM).
 
  OPM 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 2 of the License, or
  (at your option) any later version.
 
  OPM 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 OPM.  If not, see <http://www.gnu.org/licenses/>.
 
  Consult the COPYING file in the top-level source directory of this
  module for the precise wording of the license and the list of
  copyright holders.
*/
#ifndef OPM_PENG_ROBINSON_PARAMS_MIXTURE_HPP
#define OPM_PENG_ROBINSON_PARAMS_MIXTURE_HPP
 
#include "PengRobinsonParams.hpp"
 
#include <opm/material/common/MathToolbox.hpp>
#include <opm/material/Constants.hpp>
 
#include <algorithm>
 
namespace Opm
{
 
template <class Scalar, class FluidSystem, unsigned phaseIdx, bool useSpe5Relations=false>
class PengRobinsonParamsMixture
    : public PengRobinsonParams<Scalar>
{
    enum { numComponents = FluidSystem::numComponents };
 
    // Peng-Robinson parameters for pure substances
    typedef PengRobinsonParams<Scalar> PureParams;
 
    typedef MathToolbox<Scalar> Toolbox;
 
public:
 
    Scalar getaCache(unsigned compIIdx, unsigned compJIdx ) const
    {
        return aCache_[compIIdx][compJIdx];
    }
 
    template <class FluidState>
    void updatePure(const FluidState& fluidState)
    {
        updatePure(fluidState.temperature(phaseIdx),
                   fluidState.pressure(phaseIdx));
    }
 
    void updatePure(Scalar temperature, Scalar pressure)
    {
        Valgrind::CheckDefined(temperature);
        Valgrind::CheckDefined(pressure);
 
        // Calculate the Peng-Robinson parameters of the pure
        // components
        //
        // See: R. Reid, et al.: The Properties of Gases and Liquids,
        // 4th edition, McGraw-Hill, 1987, p. 43
        for (unsigned i = 0; i < numComponents; ++i) {
            Scalar pc = FluidSystem::criticalPressure(i);
            Scalar omega = FluidSystem::acentricFactor(i);
            Scalar Tr = temperature/FluidSystem::criticalTemperature(i);
            Scalar RTc = Constants<Scalar>::R*FluidSystem::criticalTemperature(i);
 
            Scalar f_omega;
 
            if (omega < 0.49) 
                f_omega = 0.37464  + omega*(1.54226 + omega*(-0.26992));
            else              
                f_omega = 0.379642 + omega*(1.48503 + omega*(-0.164423 + omega*0.016666));
 
            Valgrind::CheckDefined(f_omega);
 
            Scalar tmp = 1 + f_omega*(1 - sqrt(Tr));
            tmp = tmp*tmp;
 
            Scalar newA = 0.4572355*RTc*RTc/pc * tmp;
            Scalar newB = 0.0777961 * RTc / pc;
            assert(std::isfinite(scalarValue(newA)));
            assert(std::isfinite(scalarValue(newB)));
 
            this->pureParams_[i].setA(newA);
            this->pureParams_[i].setB(newB);
            Valgrind::CheckDefined(this->pureParams_[i].a());
            Valgrind::CheckDefined(this->pureParams_[i].b());
        }
 
        updateACache_();
    }
 
    template <class FluidState>
    void updateMix(const FluidState& fs)
    {
        using FlashEval = typename FluidState::Scalar;
        Scalar sumx = 0.0;
        for (unsigned compIdx = 0; compIdx < numComponents; ++compIdx)
            sumx += fs.moleFraction(phaseIdx, compIdx);
        sumx = std::max(Scalar(1e-10), sumx);
 
        // Calculate the Peng-Robinson parameters of the mixture
        //
        // See: R. Reid, et al.: The Properties of Gases and Liquids,
        // 4th edition, McGraw-Hill, 1987, p. 82
        FlashEval newA = 0;
        FlashEval newB = 0;
        for (unsigned compIIdx = 0; compIIdx < numComponents; ++compIIdx) {
            const FlashEval moleFracI = fs.moleFraction(phaseIdx, compIIdx);
            FlashEval xi = max(0.0, min(1.0, moleFracI));
            Valgrind::CheckDefined(xi);
 
            for (unsigned compJIdx = 0; compJIdx < numComponents; ++compJIdx) {
                const FlashEval moleFracJ = fs.moleFraction(phaseIdx, compJIdx );
                FlashEval xj = max(0.0, min(1.0, moleFracJ));
                Valgrind::CheckDefined(xj);
 
                // mixing rule from Reid, page 82
                newA +=  xi * xj * aCache_[compIIdx][compJIdx];
 
                assert(std::isfinite(scalarValue(newA)));
            }
 
            // mixing rule from Reid, page 82
            newB += max(0.0, xi) * this->pureParams_[compIIdx].b();
            assert(std::isfinite(scalarValue(newB)));
        }
 
        // assert(newB > 0);
        this->setA(newA);
        this->setB(newB);
 
        Valgrind::CheckDefined(this->a());
        Valgrind::CheckDefined(this->b());
 
    }
 
    template <class FluidState>
    void updateSingleMoleFraction(const FluidState& fs,
                                  unsigned /*compIdx*/)
    {
        updateMix(fs);
    }
 
    const PureParams& pureParams(unsigned compIdx) const
    { return pureParams_[compIdx]; }
 
    const PureParams& operator[](unsigned compIdx) const
    {
        assert(0 <= compIdx && compIdx < numComponents);
        return pureParams_[compIdx];
    }
 
    void checkDefined() const
    {
#ifndef NDEBUG
        for (unsigned i = 0; i < numComponents; ++i)
            pureParams_[i].checkDefined();
 
        Valgrind::CheckDefined(this->a());
        Valgrind::CheckDefined(this->b());
#endif
    }
 
protected:
    PureParams pureParams_[numComponents];
 
private:
    void updateACache_()
    {
        for (unsigned compIIdx = 0; compIIdx < numComponents; ++ compIIdx) {
            for (unsigned compJIdx = 0; compJIdx < numComponents; ++ compJIdx) {
                // interaction coefficient as given in SPE5
                Scalar Psi = FluidSystem::interactionCoefficient(compIIdx, compJIdx);
 
                aCache_[compIIdx][compJIdx] =
                    sqrt(this->pureParams_[compIIdx].a()
                                  * this->pureParams_[compJIdx].a())
                    * (1 - Psi);
            }
        }
    }
 
    Scalar aCache_[numComponents][numComponents];
};
 
 
} // namespace Opm
 
#endif