Buildings.Fluid.HeatExchangers.Examples.BaseClasses

Information

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

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

Package Content

Name	Description
EffectivenessNTUMassFlow	Partial model of epsilon-NTU coil that tests variable mass flow rates

Buildings.Fluid.HeatExchangers.Examples.BaseClasses.EffectivenessNTUMassFlow

Parameters

Type	Name	Default	Description
Temperature	T_a1_nominal	5 + 273.15	[K]
Temperature	T_b1_nominal	10 + 273.15	[K]
Temperature	T_a2_nominal	30 + 273.15	[K]
Temperature	T_b2_nominal	15 + 273.15	[K]
HeatFlowRate	Q_flow_nominal	m1_flow_nominal*4200*(T_a1_n...	Nominal heat transfer [W]
MassFlowRate	m1_flow_nominal	0.1	Nominal mass flow rate medium 1 [kg/s]
MassFlowRate	m2_flow_nominal	m1_flow_nominal*4200/1000*(T...	Nominal mass flow rate medium 2 [kg/s]

Modelica definition

partial model EffectivenessNTUMassFlow 
  "Partial model of epsilon-NTU coil that tests variable mass flow rates"
  import Buildings;
  package Medium1 = Buildings.Media.ConstantPropertyLiquidWater;
  package Medium2 = Buildings.Media.PerfectGases.MoistAirUnsaturated;
  parameter Modelica.SIunits.Temperature T_a1_nominal=5 + 273.15;
  parameter Modelica.SIunits.Temperature T_b1_nominal=10 + 273.15;
  parameter Modelica.SIunits.Temperature T_a2_nominal=30 + 273.15;
  parameter Modelica.SIunits.Temperature T_b2_nominal=15 + 273.15;
  parameter Modelica.SIunits.HeatFlowRate Q_flow_nominal = m1_flow_nominal*4200*(T_a1_nominal-T_b1_nominal) 
    "Nominal heat transfer";
  parameter Modelica.SIunits.MassFlowRate m1_flow_nominal=0.1 
    "Nominal mass flow rate medium 1";
  parameter Modelica.SIunits.MassFlowRate m2_flow_nominal=m1_flow_nominal*4200/
      1000*(T_a1_nominal - T_b1_nominal)/(T_b2_nominal - T_a2_nominal) 
    "Nominal mass flow rate medium 2";
  Buildings.Fluid.Sources.Boundary_pT sin_2(
    redeclare package Medium = Medium2,
    use_p_in=false,
    p(displayUnit="Pa") = 101325,
    T=T_a2_nominal);
  Buildings.Fluid.Sources.MassFlowSource_T sou_2(
    redeclare package Medium = Medium2,
    T=T_a2_nominal,
    X={0.02,1 - 0.02},
    use_T_in=true,
    use_X_in=true,
    m_flow=m2_flow_nominal,
    use_m_flow_in=true);
  Buildings.Fluid.Sources.Boundary_pT sin_1(
    redeclare package Medium = Medium1,
    use_p_in=false,
    p=300000,
    T=T_a1_nominal);
  Buildings.Fluid.Sources.MassFlowSource_T sou_1(
    redeclare package Medium = Medium1,
    use_m_flow_in=true,
    use_T_in=false,
    T=T_a1_nominal);

  inner Modelica.Fluid.System system;
  Modelica.Blocks.Sources.Constant const(k=0.8);
  Buildings.Utilities.Psychrometrics.X_pTphi x_pTphi(use_p_in=false);
  Modelica.Blocks.Sources.Constant const1(k=T_a2_nominal);
  Modelica.Blocks.Math.Gain mWat_flow(k=m1_flow_nominal) "Water mass flow rate";
  Modelica.Blocks.Sources.TimeTable mWatGai(
    table=[0,1; 3600*0.1,1; 3600*0.2,0.01; 3600*0.3,0.01]) 
    "Gain for water mass flow rate";
  Modelica.Blocks.Sources.TimeTable mAirGai(
    table=[0,1; 3600*0.5,1; 3600*0.6,-1; 3600*0.7,0; 3600*1,0]) 
    "Gain for air mass flow rate";
  Modelica.Blocks.Math.Gain mAir_flow(k=m2_flow_nominal) "Air mass flow rate";
equation 
  connect(x_pTphi.X, sou_2.X_in);
  connect(const.y, x_pTphi.phi);
  connect(const1.y, x_pTphi.T);
  connect(const1.y, sou_2.T_in);
  connect(mWat_flow.y, sou_1.m_flow_in);
  connect(mAir_flow.y, sou_2.m_flow_in);
  connect(mAirGai.y, mAir_flow.u);
  connect(mWatGai.y, mWat_flow.u);
end EffectivenessNTUMassFlow;