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Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses

Package with base classes for Buildings.Fluid.HeatExchangers.RadiantSlabs

Information

This package contains base classes that are used to construct the models in Buildings.Fluid.HeatExchangers.RadiantSlabs.

Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).

Package Content

Name Description
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.InternalFlowConvection InternalFlowConvection Convective heat transfer in pipes
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.HeatFlowRateMultiplier HeatFlowRateMultiplier Multiplies the heat flow rate
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.MassFlowRateMultiplier MassFlowRateMultiplier Model that multiplies the mass flow rate
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Slab Slab Base class for radiant slab
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Functions Functions Functions for convective heat transfer
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Types Types Types for radiant slab model

Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.InternalFlowConvection Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.InternalFlowConvection

Convective heat transfer in pipes

Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.InternalFlowConvection

Information

Model to compute the convective heat transfer inside a straight pipe. The convective heat transfer coefficient is computed as a function of the mass flow rate using the function Modelica.Fluid.Dissipation.HeatTransfer.StraightPipe.kc_overall_KC. 



Parameters




TypeNameDefaultDescription


replaceable package MediumModelica.Media.Interfaces.Pa...Medium in the component


AreaA Pipe inside surface area [m2]


kc_overall_IN_conkc_IN_con Parameters for convective heat transfer calculation




Connectors




TypeNameDescription


replaceable package MediumMedium in the component


HeatPort_asolidHeat port at solid interface


HeatPort_bfluidHeat port at fluid interface


input RealInputm_flowFluid mass flow rate [kg/s]




Modelica definition


model InternalFlowConvection "Convective heat transfer in pipes"
  replaceable package Medium =
    Modelica.Media.Interfaces.PartialMedium "Medium in the component";
  Modelica.SIunits.HeatFlowRate Q_flow "Heat flow rate from solid -> fluid";
  Modelica.SIunits.TemperatureDifference dT "= solid.T - fluid.T";
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a solid 
    "Heat port at solid interface";
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_b fluid 
    "Heat port at fluid interface";
  parameter Modelica.SIunits.Area A "Pipe inside surface area";
  parameter Modelica.Fluid.Dissipation.HeatTransfer.StraightPipe.kc_overall_IN_con
    kc_IN_con "Parameters for convective heat transfer calculation";
  Modelica.Fluid.Dissipation.HeatTransfer.StraightPipe.kc_overall_IN_var
    kc_IN_var(
    cp=Medium.specificHeatCapacityCp(fluSta),
    eta=Medium.dynamicViscosity(fluSta),
    lambda=Medium.thermalConductivity(fluSta),
    rho=Medium.density(fluSta),
    m_flow=m_flow) "Variables for convective heat transfer calculation";
  Modelica.Blocks.Interfaces.RealInput m_flow(unit="kg/s") 
    "Fluid mass flow rate";
  Modelica.SIunits.CoefficientOfHeatTransfer hCon 
    "Convective heat transfer coefficient";
protected 
  Medium.ThermodynamicState fluSta = Medium.setState_pTX(p=Medium.p_default, T=fluid.T, X=Medium.X_default) 
    "State of the medium";
equation 
  hCon = Modelica.Fluid.Dissipation.HeatTransfer.StraightPipe.kc_overall_KC(
     IN_con=kc_IN_con, IN_var=kc_IN_var);

  dT = solid.T - fluid.T;
  solid.Q_flow = Q_flow;
  fluid.Q_flow = -Q_flow;
  Q_flow = hCon*A*dT;
end InternalFlowConvection;







Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.HeatFlowRateMultiplier
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.HeatFlowRateMultiplier



Multiplies the heat flow rate



Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.HeatFlowRateMultiplier



Information




This model multiplies the heat flow rate so that
0 = port_b.Q_flow + k * port_Q.m_flow.




The temperature remains unchanged.
Therefore, this model does not conserve energy.
It is used in 

Buildings.Fluid.HeatExchangers.RadiantSlabs.ParallelCircuitsSlab
to avoid having to instanciate multiple slab models in parallel, with each
having the same mass flow rate and temperatures.




Parameters




TypeNameDefaultDescription


Realk Gain for mass flow rate




Connectors




TypeNameDescription


HeatPort_aport_a 


HeatPort_bport_b 




Modelica definition


model HeatFlowRateMultiplier "Multiplies the heat flow rate"

  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a port_a;
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_b port_b;
  parameter Real k "Gain for mass flow rate";
initial equation 
  assert( k > Modelica.Constants.small or -k < -Modelica.Constants.small,
    "Gain must not be zero. Received k = " + String(k));
equation 
  // Energy balance. (Energy is not conserved by this model!)
  port_b.Q_flow = -k*port_a.Q_flow;
  port_a.T = port_b.T;
end HeatFlowRateMultiplier;







Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.MassFlowRateMultiplier
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.MassFlowRateMultiplier



Model that multiplies the mass flow rate



Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.MassFlowRateMultiplier



Information




This model multiplies the mass flow rate so that
0 = port_b.m_flow + k * port_a.m_flow.




The specific enthalpy, the species concentration and the trace substance concentration
remains unchanged.
Therefore, this model does not conserve mass or energy.
It is used in 

Buildings.Fluid.HeatExchangers.RadiantSlabs.ParallelCircuitsSlab
to avoid having to instanciate multiple slab models in parallel, with each
having the same mass flow rate and temperatures.




Extends from Modelica.Fluid.Interfaces.PartialTwoPort (Partial component with two ports).


Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Realk Gain for mass flow rate


Assumptions


BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)




Connectors




TypeNameDescription


FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)


FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)




Modelica definition


model MassFlowRateMultiplier 
  "Model that multiplies the mass flow rate"
  extends Modelica.Fluid.Interfaces.PartialTwoPort;

  parameter Real k "Gain for mass flow rate";
initial equation 
  assert( k > Modelica.Constants.small or -k < -Modelica.Constants.small,
    "Gain must not be zero. Received k = " + String(k));
equation 
    // Pressure drop in design flow direction
  port_a.p = port_b.p;

  // Mass balance (mass is not conserved by this model!)
 port_b.m_flow = -k*port_a.m_flow;

  // Specific enthalpy flow rate
  port_a.h_outflow = inStream(port_b.h_outflow);
  port_b.h_outflow = inStream(port_a.h_outflow);
  // Transport of substances
  port_a.Xi_outflow = inStream(port_b.Xi_outflow);
  port_b.Xi_outflow = inStream(port_a.Xi_outflow);

  port_a.C_outflow = inStream(port_b.C_outflow);
  port_b.C_outflow = inStream(port_a.C_outflow);

end MassFlowRateMultiplier;







Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Slab
Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Slab



Base class for radiant slab



Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Slab



Information




This partial model is used to construct radiant slab models with one circuit or with multiple parallel circuits.




Parameters




TypeNameDefaultDescription


SystemTypesysTyp Radiant system type


DistancedisPip Pipe distance [m]


Genericpipe Record for pipe geometry and material


Construction


Genericlayers Definition of the construction, which must have at least two material layers


IntegeriLayPip Number of the interface layer in which the pipes are located


Initialization


Construction


BooleansteadyStateInitialfalse=true initializes dT(0)/dt=0, false initializes T(0) at fixed temperature using T_a_start, T_c_start and T_b_start


TemperatureT_a_start293.15Initial temperature at surf_a, used if steadyStateInitial = false [K]


TemperatureT_b_start293.15Initial temperature at surf_b, used if steadyStateInitial = false [K]




Connectors




TypeNameDescription


HeatPort_asurf_aHeat port at construction surface


HeatPort_asurf_bHeat port at construction surface




Modelica definition


partial model Slab "Base class for radiant slab"
  parameter Buildings.Fluid.HeatExchangers.RadiantSlabs.BaseClasses.Types.SystemType
     sysTyp "Radiant system type";

  parameter Modelica.SIunits.Distance disPip "Pipe distance";

  parameter Buildings.Fluid.Data.Pipes.Generic pipe 
    "Record for pipe geometry and material";

  parameter HeatTransfer.Data.OpaqueConstructions.Generic layers(nLay(min=2)) 
    "Definition of the construction, which must have at least two material layers";
  parameter Boolean steadyStateInitial=false 
    "=true initializes dT(0)/dt=0, false initializes T(0) at fixed temperature using T_a_start, T_c_start and T_b_start";

  parameter Integer iLayPip(min=1) 
    "Number of the interface layer in which the pipes are located";

  parameter Modelica.SIunits.Temperature T_a_start=293.15 
    "Initial temperature at surf_a, used if steadyStateInitial = false";
  parameter Modelica.SIunits.Temperature T_b_start=293.15 
    "Initial temperature at surf_b, used if steadyStateInitial = false";

  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a surf_a 
    "Heat port at construction surface";
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a surf_b 
    "Heat port at construction surface";
end Slab;






Automatically generated Thu Jun 19 10:56:18 2014.