BHECommonCoaxial.cpp

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// SPDX-FileCopyrightText: Copyright (c) OpenGeoSys Community (opengeosys.org)
// SPDX-License-Identifier: BSD-3-Clause
 
#include "BHECommonCoaxial.h"
 
#include "ThermalResistancesCoaxial.h"
#include "ThermoMechanicalFlowProperties.h"
 
namespace ProcessLib
{
namespace HeatTransportBHE
{
namespace BHE
{
BHECommonCoaxial::BHECommonCoaxial(
    BoreholeGeometry const& borehole,
    RefrigerantProperties const& refrigerant,
    GroutParameters const& grout,
    FlowAndTemperatureControl const& flowAndTemperatureControl,
    PipeConfigurationCoaxial const& pipes,
    bool const use_python_bcs)
    : BHECommon{borehole, refrigerant, grout, flowAndTemperatureControl,
                use_python_bcs},
      _pipes(pipes)
{
    cross_section_area_inner_pipe = _pipes.inner_pipe.area();
    cross_section_area_annulus =
        _pipes.outer_pipe.area() - _pipes.inner_pipe.outsideArea();
}
 
std::array<double, BHECommonCoaxial::number_of_unknowns>
BHECommonCoaxial::pipeHeatCapacities() const
{
    double const rho_r = refrigerant.density;
    double const specific_heat_capacity = refrigerant.specific_heat_capacity;
    double const rho_g = grout.rho_g;
    double const porosity_g = grout.porosity_g;
    double const heat_cap_g = grout.heat_cap_g;
 
    return {{/*i*/ rho_r * specific_heat_capacity,
             /*o*/ rho_r * specific_heat_capacity,
             /*g*/ (1.0 - porosity_g) * rho_g * heat_cap_g}};
}
 
double BHECommonCoaxial::updateFlowRateAndTemperature(double const T_out,
                                                      double const current_time)
{
    auto values =
        visit([&](auto const& control) { return control(T_out, current_time); },
              flowAndTemperatureControl);
    updateHeatTransferCoefficients(values.flow_rate);
    return values.temperature;
}
std::array<double, BHECommonCoaxial::number_of_unknowns>
BHECommonCoaxial::pipeHeatConductions(int /*section_index*/) const
{
    // Pipe dimensions are constant; velocity does not vary by section.
    double const lambda_r = refrigerant.thermal_conductivity;
    double const rho_r = refrigerant.density;
    double const Cp_r = refrigerant.specific_heat_capacity;
    double const alpha_L = _pipes.longitudinal_dispersion_length;
    double const porosity_g = grout.porosity_g;
    double const lambda_g = grout.lambda_g;
 
    auto v = velocities();
    // Here we calculate the laplace coefficients in the governing
    // equations of BHE. These governing equations can be found in
    // 1) Diersch (2013) FEFLOW book on page 952, M.120-122, or
    // 2) Diersch (2011) Comp & Geosci 37:1122-1135, Eq. 26-28, 23-25
    return {{// pipe i, Eq. 26 and Eq. 23
             (lambda_r + rho_r * Cp_r * alpha_L * std::abs(v[0])),
             // pipe o, Eq. 27 and Eq. 24
             (lambda_r + rho_r * Cp_r * alpha_L * std::abs(v[1])),
             // pipe g, Eq. 28 and Eq. 25
             (1.0 - porosity_g) * lambda_g}};
}
 
std::array<Eigen::Vector3d, BHECommonCoaxial::number_of_unknowns>
BHECommonCoaxial::pipeAdvectionVectors(Eigen::Vector3d const& elem_direction,
                                       int /*section_index*/) const
{
    // Pipe dimensions are constant; velocity does not vary by section.
    double const rho_r = refrigerant.density;
    double const Cp_r = refrigerant.specific_heat_capacity;
    auto const v = velocities();
 
    return {// pipe i, Eq. 26 and Eq. 23
            rho_r * Cp_r * std::abs(v[0]) * elem_direction,
            // pipe o, Eq. 27 and Eq. 24
            -rho_r * Cp_r * std::abs(v[1]) * elem_direction,
            // grout g, Eq. 28 and Eq. 25
            {0, 0, 0}};
}
 
std::vector<double> BHECommonCoaxial::calcThermalResistances(
    double const Nu_inner_pipe, double const Nu_annulus_pipe,
    int const section_index) const
{
    // thermal resistances due to advective flow of refrigerant in the pipes
    auto const R_advective = calculateAdvectiveThermalResistance(
        _pipes.inner_pipe, _pipes.outer_pipe, refrigerant, Nu_inner_pipe,
        Nu_annulus_pipe);
 
    // thermal resistance due to thermal conductivity of the pipe wall material
    auto const R_conductive = calculatePipeWallThermalResistance(
        _pipes.inner_pipe, _pipes.outer_pipe);
 
    // thermal resistance due to the grout transition and grout-soil exchange.
    auto const R = calculateGroutAndGroutSoilExchangeThermalResistance(
        _pipes.outer_pipe, grout,
        borehole_geometry.sections.diameterAtSection(section_index));
 
    // thermal resistance due to grout-soil exchange
    double const R_gs = R.grout_soil;
 
    // Eq. 56 and 57
    double const R_ff = R_advective.inner_pipe_coaxial + R_advective.a_annulus +
                        R_conductive.inner_pipe_coaxial;
    double const R_fg =
        R_advective.b_annulus + R_conductive.annulus + R.conductive_b;
 
    return getThermalResistances(R_gs, R_ff, R_fg);
}
 
std::array<std::pair<std::size_t /*node_id*/, int /*component*/>, 2>
BHECommonCoaxial::getBHEInflowDirichletBCNodesAndComponents(
    std::size_t const top_node_id,
    std::size_t const /*bottom_node_id*/,
    int const in_component_id)
{
    return {std::make_pair(top_node_id, in_component_id),
            std::make_pair(top_node_id, in_component_id + 1)};
}
 
std::optional<
    std::array<std::pair<std::size_t /*node_id*/, int /*component*/>, 2>>
BHECommonCoaxial::getBHEBottomDirichletBCNodesAndComponents(
    std::size_t const bottom_node_id, int const in_component_id,
    int const out_component_id)
{
    return {{std::make_pair(bottom_node_id, in_component_id),
             std::make_pair(bottom_node_id, out_component_id)}};
}
 
void BHECommonCoaxial::updateHeatTransferCoefficients(double const flow_rate)
{
    auto const tm_flow_inner = calculateThermoMechanicalFlowPropertiesPipe(
        _pipes.inner_pipe, borehole_geometry.length, refrigerant, flow_rate);
 
    auto const tm_flow_annulus = calculateThermoMechanicalFlowPropertiesAnnulus(
        _pipes.inner_pipe, _pipes.outer_pipe, borehole_geometry.length,
        refrigerant, flow_rate);
 
    assignVelocities(tm_flow_inner.velocity, tm_flow_annulus.velocity);
 
    recomputeSectionalResistances(
        [&](int i)
        {
            return calcThermalResistances(tm_flow_inner.nusselt_number,
                                          tm_flow_annulus.nusselt_number, i);
        });
}
}  // namespace BHE
}  // namespace HeatTransportBHE
}  // namespace ProcessLib