comfort.H

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    Copyright (C) 2021 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.
 
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    the Free Software Foundation, either version 3 of the License, or
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    You should have received a copy of the GNU General Public License
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Class
    Foam::functionObjects::comfort
 
Description
    Calculates the thermal comfort quantities predicted mean vote (PMV),
    predicted percentage of dissatisfaction (PPD) and the draught rate (DR)
    based on DIN ISO EN 7730:2005.
 
    The draught rate is defined for velocities between 0 m/s and 0.5 m/s. Values
    larger than 0.5 m/s will be set to 0.5 m/s. Furthermore, the draught rate is
    defined between 20 degC and 26 degC. A temperature limitation is not
    implemented. The draught rate is mainly used for HVAC analysis in rooms.
 
Usage
    Minimal example by using \c system/controlDict.functions:
    \verbatim
    comfortFO
    {
        // Mandatory entries
        type            comfort;
        libs            (fieldFunctionObjects);
 
        // Optional entries
        clothing        <scalar>;
        metabolicRate   <scalar>;
        extWork         <scalar>;
        Trad            <scalar>;
        relHumidity     <scalar>;
        pSat            <scalar>;
        tolerance       <scalar>;
        maxClothIter    <int>;
        meanVelocity    <bool>;
 
        // Inherited entries
        ...
    }
    \endverbatim
 
    where the entries mean:
    \table
      Property  | Description                        | Type | Reqd | Deflt
      type      | Type name: comfort                 | word | yes  | -
      libs      | Library name: fieldFunctionObjects | word | yes  | -
      clothing  | The insulation value of the cloth  | scalar | no | 0
      metabolicRate | The metabolic rate             | scalar | no | 0.8
      extWork   | The external work                  | scalar | no | 0
      Trad      | Radiation temperature              | scalar | no | 0
      relHumidity   | Relative humidity of the air   | scalar | no | 0.5
      pSat      | Saturation pressure of water       | scalar | no | -1
      tolerance | Residual control for the cloth temperature <!--
                -->                                  | scalar | no | 1e-4
      maxClothIter  | Maximum number of iterations   | int    | no | 100
      meanVelocity  | Flag to use a constant mean velocity   <!--
                -->             in the whole domain  | bool   | no | false
    \endtable
 
    The inherited entries are elaborated in:
      - \link functionObject.H \endlink
 
    \table
        Predicted Mean Vote (PMV)   | evaluation
        + 3                         | hot
        + 2                         | warm
        + 1                         | slightly warm
        + 0                         | neutral
        - 1                         | slightly cool
        - 2                         | cool
        - 3                         | cold
    \endtable
 
    \table
        Draught rate based on 7730  | category
        0 - 10                      | I - fine
        10 - 20                     | II - okay
        20 - 30                     | III - intermedian
        > 30                        | bad - commonly too high
    \endtable
 
See also
  - Foam::functionObjects::age
 
SourceFiles
    comfort.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef Foam_functionObjects_comfort_H
#define Foam_functionObjects_comfort_H
 
#include "fvMeshFunctionObject.H"
#include "volFields.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace functionObjects
{
 
/*---------------------------------------------------------------------------*\
                           Class comfort Declaration
\*---------------------------------------------------------------------------*/
 
class comfort
:
    public fvMeshFunctionObject
{
    // Private Data
 
        //- Wall patch IDs
        mutable labelList wallPatchIDs_;
 
        //- Clothing [-]
        dimensionedScalar clothing_;
 
        //- Metabolic rate [kg/s^3]
        dimensionedScalar metabolicRate_;
 
        //- External work [kg/s^3]
        dimensionedScalar extWork_;
 
        //- Mean radiation temperature [K]
        dimensionedScalar Trad_;
 
        //- Relative humidity [percentage]
        dimensionedScalar relHumidity_;
 
        //- Saturation pressure of water [Pa]
        dimensionedScalar pSat_;
 
        //- Thermal insulation of clothing [W/m^2/K]
        dimensionedScalar Icl_;
 
        //- Prefactor of cloth area [-]
        dimensionedScalar fcl_;
 
        //- Tolerance criteria for iterative process to find Tcl
        scalar tolerance_;
 
        //- Global sum of wall area [m^2]
        mutable scalar wallArea_;
 
        //- Maximum number of correctors for cloth temperature
        int maxClothIter_;
 
        //- Flag to indicate if wall info has been initialized
        mutable bool wallInfoInit_;
 
        //- Flag to set to true if the radiation temperature is provided
        bool TradSet_;
 
        //- Flag to use volume weighted velocity field for caluclation
        bool meanVelocity_;
 
 
    // Private Member Functions
 
        //- Calculate the magnitude of the velocity [m/s]
        tmp<volScalarField> magU() const;
 
        //- Initialize wall caches for Trad() (ids + global area)
        void initWallInfo() const;
 
        //- Calculate the radiation temperature in the domain using a simple
        //- approach [K]
        dimensionedScalar Trad() const;
 
        //- Calculate the saturation pressure based on 7730:2005
        //- Possible options: adding different calculation methods such as
        //- the formulation based on Magnus or others [Pa]
        tmp<volScalarField> pSat() const;
 
        //- Calculate and return the surface temperature of the cloth [K]
        //- and the heat transfer coefficient hc [W/m^2/K]
        tmp<volScalarField> Tcloth
        (
            volScalarField& hc,
            const dimensionedScalar& metabolicRateSI,
            const dimensionedScalar& extWorkSI,
            const volScalarField& TdegC,
            const dimensionedScalar& Trad
        );
 
        //- Return true if the cloth temperature iteration has converged
        bool converged(const volScalarField&) const;
 
 
public:
 
    //- Runtime type information
    TypeName("comfort");
 
 
    // Constructors
 
        //- Construct from name, Time and dictionary
        comfort
        (
            const word& name,
            const Time& runTime,
            const dictionary& dict
        );
 
 
    //- Destructor
    virtual ~comfort() = default;
 
 
    // Member Functions
 
        //- Read the function-object dictionary
        virtual bool read(const dictionary& dict);
 
        //- Execute the function-object operations
        virtual bool execute();
 
        //- Write the function-object results
        virtual bool write();
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace functionObjects
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //