Buildings.Fluid.Boilers.Examples

Information

This package contains examples for the use of models that can be found in Buildings.Fluid.Boilers.

Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).

Package Content

Name	Description
BoilerPolynomial	Test model
BoilerPolynomialClosedLoop	Boiler with closed loop control

Buildings.Fluid.Boilers.Examples.BoilerPolynomial

Information

Parameters

Type	Name	Default	Description
Power	Q_flow_nominal	3000	Nominal power [W]
Temperature	dT_nominal	20	Nominal temperature difference [K]
MassFlowRate	m_flow_nominal	Q_flow_nominal/dT_nominal/4200	Nominal mass flow rate [kg/s]
Pressure	dp_nominal	3000	Pressure drop at m_flow_nominal [Pa]

Modelica definition

model BoilerPolynomial "Test model"
  extends Modelica.Icons.Example;
 package Medium = Buildings.Media.ConstantPropertyLiquidWater "Medium model";
 parameter Modelica.SIunits.Power Q_flow_nominal = 3000 "Nominal power";
 parameter Modelica.SIunits.Temperature dT_nominal = 20 
    "Nominal temperature difference";
 parameter Modelica.SIunits.MassFlowRate m_flow_nominal = Q_flow_nominal/dT_nominal/4200 
    "Nominal mass flow rate";
 parameter Modelica.SIunits.Pressure dp_nominal = 3000 
    "Pressure drop at m_flow_nominal";
  inner Modelica.Fluid.System system;

  Buildings.Fluid.Sources.Boundary_pT sin(
    redeclare package Medium = Medium,
    nPorts=2,
    p(displayUnit="Pa") = 300000,
    T=333.15) "Sink";
  Buildings.Fluid.Sources.Boundary_pT sou(
    nPorts=2,
    redeclare package Medium = Medium,
    p=300000 + dp_nominal,
    T=303.15);
  Modelica.Blocks.Sources.TimeTable y(table=[0,0; 1800,1; 1800,0; 2400,0; 2400,
        1; 3600,1]);
  Buildings.Fluid.Boilers.BoilerPolynomial fur1(
    a={0.9},
    effCur=Buildings.Fluid.Types.EfficiencyCurves.Constant,
    Q_flow_nominal=Q_flow_nominal,
    m_flow_nominal = m_flow_nominal,
    redeclare package Medium = Medium,
    dp_nominal=dp_nominal,
    T_start=293.15) "Boiler";
  Buildings.HeatTransfer.Sources.FixedTemperature TAmb1(      T=288.15) 
    "Ambient temperature in boiler room";
  Buildings.Fluid.Boilers.BoilerPolynomial fur2(
    a={0.9},
    effCur=Buildings.Fluid.Types.EfficiencyCurves.Constant,
    Q_flow_nominal=Q_flow_nominal,
    m_flow_nominal = m_flow_nominal,
    redeclare package Medium = Medium,
    energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
    massDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
    dp_nominal=dp_nominal,
    T_start=293.15) "Boiler";
  Buildings.HeatTransfer.Sources.FixedTemperature TAmb2(      T=288.15) 
    "Ambient temperature in boiler room";
  Modelica.Blocks.Continuous.FirstOrder firstOrder(T=0.1);
equation 
  connect(TAmb1.port, fur1.heatPort);
  connect(TAmb2.port, fur2.heatPort);
  connect(sou.ports[1], fur1.port_a);
  connect(sou.ports[2], fur2.port_a);
  connect(y.y, firstOrder.u);
  connect(firstOrder.y, fur1.y);
  connect(firstOrder.y, fur2.y);
  connect(fur2.port_b, sin.ports[2]);
  connect(fur1.port_b, sin.ports[1]);
end BoilerPolynomial;

Buildings.Fluid.Boilers.Examples.BoilerPolynomialClosedLoop

Information

This model illustrates how to use a boiler model with closed loop control. The controller modulates the boiler temperature between 60°C and 80°C. A three-way valve mixes recirculated water with boiler water to regulate the temperature of the volume at a constant temperature of 40°C. There is also a bypass in the boiler loop to ensure circulation when the valve position is such that it only recirculates water from the load. The bypass between valve and pump mixes recirculated water, thereby allowing the valve to work over a larger operating range. The expansion vessel near the boiler is used to set a reference pressure, and it is used to accomodate for the thermal expansion of the water.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Power	Q_flow_nominal	20000	Nominal power [W]
Temperature	dT_nominal	20	Nominal temperature difference [K]
MassFlowRate	m_flow_nominal	Q_flow_nominal/dT_nominal/4200	Nominal mass flow rate [kg/s]

Modelica definition

model BoilerPolynomialClosedLoop "Boiler with closed loop control"
  extends Modelica.Icons.Example;
 package Medium = Buildings.Media.ConstantPropertyLiquidWater "Medium model";
 parameter Modelica.SIunits.Power Q_flow_nominal = 20000 "Nominal power";
 parameter Modelica.SIunits.Temperature dT_nominal = 20 
    "Nominal temperature difference";
 parameter Modelica.SIunits.MassFlowRate m_flow_nominal = Q_flow_nominal/dT_nominal/4200 
    "Nominal mass flow rate";

  inner Modelica.Fluid.System system;

  Buildings.Fluid.Boilers.BoilerPolynomial fur(
    a={0.9},
    effCur=Buildings.Fluid.Types.EfficiencyCurves.Constant,
    Q_flow_nominal=Q_flow_nominal,
    redeclare package Medium = Medium,
    dp_nominal=20000,
    T_start=293.15,
    m_flow_nominal=m_flow_nominal) "Boiler";
  Modelica.Blocks.Logical.OnOffController onOffController(bandwidth=20);
  Modelica.Blocks.Math.BooleanToReal booleanToReal;
  Actuators.Valves.ThreeWayEqualPercentageLinear val(
                          redeclare package Medium = Medium,
    l={0.01,0.01},
    dynamicBalance=false,
    m_flow_nominal=m_flow_nominal);
  Movers.FlowMachine_m_flow pumLoa(redeclare package Medium = Medium,
    dynamicBalance=false,
    m_flow_nominal=2*m_flow_nominal) "Pump for heating load";
  Movers.FlowMachine_m_flow pumFur(redeclare package Medium = Medium,
      m_flow_nominal=m_flow_nominal,
    dynamicBalance=false) "Pump for furnace loop";
  Modelica.Blocks.Sources.Constant m_flow_pum(k=m_flow_nominal) 
    "Mass flow rate of pump";
  Modelica.Blocks.Sources.Constant TSetFur(k=273.15 + 70) 
    "Temperature setpoint for furnace";
  Controls.Continuous.LimPID conPID(
    Td=1,
    k=1,
    controllerType=Modelica.Blocks.Types.SimpleController.PI,
    Ti=100);
  Modelica.Blocks.Sources.Constant TSetHea(k=273.15 + 40) 
    "Temperature setpoint for heating load";
  FixedResistances.SplitterFixedResistanceDpM spl(
    redeclare package Medium = Medium,
    dynamicBalance=false,
    m_flow_nominal=m_flow_nominal*{1,2,1},
    dp_nominal={0,0,200}) "Splitter/mixer";
  FixedResistances.SplitterFixedResistanceDpM spl1(
    redeclare package Medium = Medium,
    m_flow_nominal=m_flow_nominal*{1,1,1},
    dynamicBalance=false,
    dp_nominal={0,0,100}) "Splitter/mixer";
  FixedResistances.SplitterFixedResistanceDpM spl2(
    redeclare package Medium = Medium,
    m_flow_nominal=m_flow_nominal*{1,1,1},
    dp_nominal=0*{1,1,1},
    dynamicBalance=false) "Splitter/mixer";
  FixedResistances.SplitterFixedResistanceDpM spl3(
    redeclare package Medium = Medium,
    dp_nominal=0*{1,1,1},
    dynamicBalance=false,
    m_flow_nominal=m_flow_nominal*{1,2,1}) "Splitter/mixer";
  Storage.ExpansionVessel exp(redeclare package Medium = Medium, VTot=2);
  FixedResistances.SplitterFixedResistanceDpM spl4(
    redeclare package Medium = Medium,
    m_flow_nominal=m_flow_nominal*{1,1,1},
    dp_nominal=0*{1,1,1},
    dynamicBalance=false) "Splitter/mixer";
  MixingVolumes.MixingVolume vol(
    nPorts=2,
    redeclare package Medium = Medium,
    m_flow_nominal=2*m_flow_nominal,
    V=1);
  Modelica.Thermal.HeatTransfer.Components.ThermalConductor thermalConductor(G=0.1
        *Q_flow_nominal/(40 - 20));
  Modelica.Thermal.HeatTransfer.Sources.FixedTemperature TBou(T=293.15) 
    "Fixed temperature boundary condition";
  Modelica.Blocks.Math.Gain gain(k=2) 
    "Multiply the mass flow rate as this circuit has a smaller temperature difference";
  Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor TVol 
    "Sensor for volume temperature";
equation 
  connect(onOffController.y, booleanToReal.u);
  connect(fur.port_b, pumFur.port_a);
  connect(fur.T, onOffController.u);
  connect(conPID.y, val.y);
  connect(TSetHea.y, conPID.u_s);
  connect(TSetFur.y, onOffController.reference);
  connect(val.port_2, spl.port_1);
  connect(spl.port_2, pumLoa.port_a);
  connect(pumFur.port_b, spl1.port_1);
  connect(spl1.port_2, val.port_1);
  connect(spl2.port_2, fur.port_a);
  connect(fur.port_a, exp.port_a);
  connect(spl3.port_2, spl4.port_1);
  connect(spl4.port_2, spl2.port_1);
  connect(spl4.port_3, val.port_3);
  connect(booleanToReal.y, fur.y);
  connect(m_flow_pum.y, pumFur.m_flow_in);
  connect(vol.ports[1], spl3.port_1);
  connect(TBou.port, thermalConductor.port_a);
  connect(thermalConductor.port_b, vol.heatPort);
  connect(gain.y, pumLoa.m_flow_in);
  connect(m_flow_pum.y, gain.u);
  connect(TVol.port, vol.heatPort);
  connect(TVol.T, conPID.u_m);
  connect(pumLoa.port_b, vol.ports[2]);
  connect(spl.port_3, spl3.port_3);
  connect(spl1.port_3, spl2.port_3);
end BoilerPolynomialClosedLoop;