Buildings.Fluid.Movers

Package with fan and pump models

Information


This package contains components models for fans and pumps.

Package Content

NameDescription
Buildings.Fluid.Movers.UsersGuide UsersGuide User's Guide
Buildings.Fluid.Movers.FlowMachine_y FlowMachine_y Fan or pump with ideally controlled normalized speed y as input signal
Buildings.Fluid.Movers.FlowMachine_Nrpm FlowMachine_Nrpm Fan or pump with ideally controlled speed Nrpm as input signal
Buildings.Fluid.Movers.FlowMachine_dp FlowMachine_dp Fan or pump with ideally controlled head dp as input signal
Buildings.Fluid.Movers.FlowMachine_m_flow FlowMachine_m_flow Fan or pump with ideally controlled mass flow rate as input signal
Buildings.Fluid.Movers.FlowMachinePolynomial FlowMachinePolynomial Fan or pump with head and efficiency declared by a non-dimensional polynomial
Buildings.Fluid.Movers.Examples Examples Collection of models that illustrate model use and test models
Buildings.Fluid.Movers.BaseClasses BaseClasses Base classes used in the Machines package (only of interest to build new component models)


Buildings.Fluid.Movers.FlowMachine_y Buildings.Fluid.Movers.FlowMachine_y

Fan or pump with ideally controlled normalized speed y as input signal

Buildings.Fluid.Movers.FlowMachine_y

Information


This model describes a fan or pump with prescribed normalized speed. The input connector provides the normalized rotational speed (between 0 and 1). The head is computed based on the performance curve that take as an argument the actual volume flow rate divided by the maximum flow rate and the relative speed of the fan. The efficiency of the device is computed based on the efficiency curves that take as an argument the actual volume flow rate divided by the maximum possible volume flow rate, or based on the motor performance curves.

See the User's Guide for more information.

Extends from Buildings.Fluid.Movers.BaseClasses.PrescribedFlowMachine (Partial model for fan or pump with speed (y or Nrpm) as input signal).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
BooleanaddPowerToMediumtrueSet to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate [kg/s]
Initialization
MassFlowRatem_flow.start0Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressuredp.start0Pressure difference between port_a and port_b [Pa]
Realr_V.start1Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)
Realr_N.start1Ratio N/N_nominal [1]
Characteristics
Booleanuse_powerCharacteristicfalseUse powerCharacteristic (vs. efficiencyCharacteristic)
BooleanmotorCooledByFluidtrueIf true, then motor heat is added to fluid stream
replaceable function motorEfficiencyBuildings.Fluid.Movers.BaseC...Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiencyBuildings.Fluid.Movers.BaseC...Efficiency vs. normalized volume flow rate
replaceable function flowCharacteristicbaseFlowTotal pressure vs. V_flow characteristic at nominal speed
AngularVelocity_rpmN_nominal1500Nominal rotational speed for flow characteristic [1/min]
replaceable function powerCharacteristicBuildings.Fluid.Movers.BaseC...Power consumption vs. V_flow at nominal speed and density
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
BooleandynamicBalancetrueSet to true to use a dynamic balance, which often leads to smaller systems of equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Formulation of energy balance (used if dynamicBalance=true)
Timetau1Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalSmall mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Booleanshow_Ttrue= true, if actual temperature at port is computed (may lead to events)
Initialization
Booleanuse_T_starttrue= true, use T_start, otherwise h_start
TemperatureT_startif use_T_start then system.T...Start value of temperature [K]
SpecificEnthalpyh_startif use_T_start then Medium.s...Start value of inlet specific enthalpy [J/kg]
MassFractionX_start[Medium.nX]Medium.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyC_start[Medium.nC]fill(0, Medium.nC)Start value of trace substances
Pressurep_startMedium.p_defaultStart value of inlet pressure [Pa]

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)
HeatPort_aheatPort 
input RealInputyConstant normalized rotational speed
Characteristics
replaceable function flowCharacteristicTotal pressure vs. V_flow characteristic at nominal speed

Modelica definition

model FlowMachine_y 
  "Fan or pump with ideally controlled normalized speed y as input signal"
  extends Buildings.Fluid.Movers.BaseClasses.PrescribedFlowMachine(
  final N_nominal=1500 "fix N_nominal as it is used only for scaling",
  redeclare replaceable function flowCharacteristic =
      Buildings.Fluid.Movers.BaseClasses.Characteristics.baseFlow);

  Modelica.Blocks.Interfaces.RealInput y(min=0, max=1) 
    "Constant normalized rotational speed";

equation 
  N = y*N_nominal;
end FlowMachine_y;

Buildings.Fluid.Movers.FlowMachine_Nrpm Buildings.Fluid.Movers.FlowMachine_Nrpm

Fan or pump with ideally controlled speed Nrpm as input signal

Buildings.Fluid.Movers.FlowMachine_Nrpm

Information


This model describes a fan or pump with prescribed speed in revolutions per minute.
The head is computed based on the performance curve that take as an argument
the actual volume flow rate divided by the maximum flow rate and the relative
speed of the fan.
The efficiency of the device is computed based
on the efficiency curves that take as an argument
the actual volume flow rate divided by the maximum possible volume flow rate, or
based on the motor performance curves.

See the User's Guide for more information.

Extends from Buildings.Fluid.Movers.BaseClasses.PrescribedFlowMachine (Partial model for fan or pump with speed (y or Nrpm) as input signal).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
BooleanaddPowerToMediumtrueSet to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate [kg/s]
Initialization
MassFlowRatem_flow.start0Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressuredp.start0Pressure difference between port_a and port_b [Pa]
Realr_V.start1Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)
Realr_N.start1Ratio N/N_nominal [1]
Characteristics
Booleanuse_powerCharacteristicfalseUse powerCharacteristic (vs. efficiencyCharacteristic)
BooleanmotorCooledByFluidtrueIf true, then motor heat is added to fluid stream
replaceable function motorEfficiencyBuildings.Fluid.Movers.BaseC...Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiencyBuildings.Fluid.Movers.BaseC...Efficiency vs. normalized volume flow rate
replaceable function flowCharacteristicbaseFlowTotal pressure vs. V_flow characteristic at nominal speed
AngularVelocity_rpmN_nominal1500Nominal rotational speed for flow characteristic [1/min]
replaceable function powerCharacteristicBuildings.Fluid.Movers.BaseC...Power consumption vs. V_flow at nominal speed and density
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
BooleandynamicBalancetrueSet to true to use a dynamic balance, which often leads to smaller systems of equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Formulation of energy balance (used if dynamicBalance=true)
Timetau1Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalSmall mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Booleanshow_Ttrue= true, if actual temperature at port is computed (may lead to events)
Initialization
Booleanuse_T_starttrue= true, use T_start, otherwise h_start
TemperatureT_startif use_T_start then system.T...Start value of temperature [K]
SpecificEnthalpyh_startif use_T_start then Medium.s...Start value of inlet specific enthalpy [J/kg]
MassFractionX_start[Medium.nX]Medium.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyC_start[Medium.nC]fill(0, Medium.nC)Start value of trace substances
Pressurep_startMedium.p_defaultStart value of inlet pressure [Pa]

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)
HeatPort_aheatPort 
input RealInputNrpmPrescribed rotational speed [1/min]

Modelica definition

model FlowMachine_Nrpm 
  "Fan or pump with ideally controlled speed Nrpm as input signal"
  extends Buildings.Fluid.Movers.BaseClasses.PrescribedFlowMachine;

  Modelica.Blocks.Interfaces.RealInput Nrpm(unit="1/min") 
    "Prescribed rotational speed";

equation 
  N = Nrpm;
end FlowMachine_Nrpm;

Buildings.Fluid.Movers.FlowMachine_dp Buildings.Fluid.Movers.FlowMachine_dp

Fan or pump with ideally controlled head dp as input signal

Buildings.Fluid.Movers.FlowMachine_dp

Information


This model describes a fan or pump with prescribed head. The input connector provides the difference between outlet minus inlet pressure. The efficiency of the device is computed based on the efficiency curves that take as an argument the actual volume flow rate divided by the maximum possible volume flow rate.

See the User's Guide for more information.

Extends from Buildings.Fluid.Movers.BaseClasses.ControlledFlowMachine (Partial model for fan or pump with ideally controlled mass flow rate or head as input signal).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
BooleanaddPowerToMediumtrueSet to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
MassFlowRatem_flow_maxm_flow_nominalMaximum mass flow rate (at zero head) [kg/s]
Booleancontrol_m_flowfalse= false to control head instead of m_flow
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate [kg/s]
Initialization
MassFlowRatem_flow.start0Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressuredp.start0Pressure difference between port_a and port_b [Pa]
Realr_V.start1Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)
Characteristics
BooleanmotorCooledByFluidtrueIf true, then motor heat is added to fluid stream
replaceable function motorEfficiencyBuildings.Fluid.Movers.BaseC...Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiencyBuildings.Fluid.Movers.BaseC...Efficiency vs. normalized volume flow rate
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
BooleandynamicBalancetrueSet to true to use a dynamic balance, which often leads to smaller systems of equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Formulation of energy balance (used if dynamicBalance=true)
Timetau1Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalSmall mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Booleanshow_Ttrue= true, if actual temperature at port is computed (may lead to events)
Initialization
Booleanuse_T_starttrue= true, use T_start, otherwise h_start
TemperatureT_startif use_T_start then system.T...Start value of temperature [K]
SpecificEnthalpyh_startif use_T_start then Medium.s...Start value of inlet specific enthalpy [J/kg]
MassFractionX_start[Medium.nX]Medium.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyC_start[Medium.nC]fill(0, Medium.nC)Start value of trace substances
Pressurep_startMedium.p_defaultStart value of inlet pressure [Pa]

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)
HeatPort_aheatPort 
input RealInputm_flow_inPrescribed mass flow rate
input RealInputdp_inPrescribed outlet pressure

Modelica definition

model FlowMachine_dp 
  "Fan or pump with ideally controlled head dp as input signal"
  extends Buildings.Fluid.Movers.BaseClasses.ControlledFlowMachine(
  final control_m_flow = false);
equation 
  assert(dp_in >= -0.1,
    "dp_in cannot be negative. Obtained dp_in = " + realString(dp_in));

end FlowMachine_dp;

Buildings.Fluid.Movers.FlowMachine_m_flow Buildings.Fluid.Movers.FlowMachine_m_flow

Fan or pump with ideally controlled mass flow rate as input signal

Buildings.Fluid.Movers.FlowMachine_m_flow

Information


This model describes a fan or pump with prescribed mass flow rate. The efficiency of the device is computed based on the efficiency curves that take as an argument the actual volume flow rate divided by the maximum possible volume flow rate.

See the User's Guide for more information.

Extends from Buildings.Fluid.Movers.BaseClasses.ControlledFlowMachine (Partial model for fan or pump with ideally controlled mass flow rate or head as input signal).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
BooleanaddPowerToMediumtrueSet to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
MassFlowRatem_flow_maxm_flow_nominalMaximum mass flow rate (at zero head) [kg/s]
Booleancontrol_m_flowtrue= false to control head instead of m_flow
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate [kg/s]
Initialization
MassFlowRatem_flow.start0Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressuredp.start0Pressure difference between port_a and port_b [Pa]
Realr_V.start1Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)
Characteristics
BooleanmotorCooledByFluidtrueIf true, then motor heat is added to fluid stream
replaceable function motorEfficiencyBuildings.Fluid.Movers.BaseC...Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiencyBuildings.Fluid.Movers.BaseC...Efficiency vs. normalized volume flow rate
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
BooleandynamicBalancetrueSet to true to use a dynamic balance, which often leads to smaller systems of equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Formulation of energy balance (used if dynamicBalance=true)
Timetau1Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalSmall mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Booleanshow_Ttrue= true, if actual temperature at port is computed (may lead to events)
Initialization
Booleanuse_T_starttrue= true, use T_start, otherwise h_start
TemperatureT_startif use_T_start then system.T...Start value of temperature [K]
SpecificEnthalpyh_startif use_T_start then Medium.s...Start value of inlet specific enthalpy [J/kg]
MassFractionX_start[Medium.nX]Medium.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyC_start[Medium.nC]fill(0, Medium.nC)Start value of trace substances
Pressurep_startMedium.p_defaultStart value of inlet pressure [Pa]

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)
HeatPort_aheatPort 
input RealInputm_flow_inPrescribed mass flow rate
input RealInputdp_inPrescribed outlet pressure

Modelica definition

model FlowMachine_m_flow 
  "Fan or pump with ideally controlled mass flow rate as input signal"
  extends Buildings.Fluid.Movers.BaseClasses.ControlledFlowMachine(
  final control_m_flow=true);
end FlowMachine_m_flow;

Buildings.Fluid.Movers.FlowMachinePolynomial Buildings.Fluid.Movers.FlowMachinePolynomial

Fan or pump with head and efficiency declared by a non-dimensional polynomial

Buildings.Fluid.Movers.FlowMachinePolynomial

Information


This is a model of a flow machine (pump or fan).

The normalized pressure difference is computed using a function of the normalized mass flow rate. The function is a polynomial for which a user needs to supply the coefficients and two values that determine for what flow rate the polynomial is linearly extended.

Note: This model is here for compatibility with older versions of this library. For new models, use instead Buildings.Fluid.Movers.FlowMachine_y.

Extends from Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface (Partial model transporting fluid between two ports without storing mass or energy).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
LengthD Diameter [m]
Reala[:] Polynomial coefficients for pressure=p(mNor_flow)
Realb[:] Polynomial coefficients for etaSha=p(mNor_flow)
RealmNorMin_flow Lowest valid normalized mass flow rate
RealmNorMax_flow Highest valid normalized mass flow rate
RealscaM_flow1Factor used to scale the mass flow rate of the fan (used for quickly adjusting fan size)
RealscaDp1Factor used to scale the pressure increase of the fan (used for quickly adjusting fan size)
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate [kg/s]
Initialization
MassFlowRatem_flow.start0Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressuredp.start0Pressure difference between port_a and port_b [Pa]
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalSmall mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Booleanshow_V_flowfalse= true, if volume flow rate at inflowing port is computed
Booleanshow_Tfalse= true, if actual temperature at port is computed (may lead to events)

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)
input RealInputN_inPrescribed rotational speed

Modelica definition

model FlowMachinePolynomial 
  "Fan or pump with head and efficiency declared by a non-dimensional polynomial"
  extends Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface;

  Modelica.Blocks.Interfaces.RealInput N_in "Prescribed rotational speed";

  parameter Modelica.SIunits.Length D "Diameter";
  parameter Real[:] a "Polynomial coefficients for pressure=p(mNor_flow)";
  parameter Real[:] b "Polynomial coefficients for etaSha=p(mNor_flow)";
  parameter Real mNorMin_flow "Lowest valid normalized mass flow rate";
  parameter Real mNorMax_flow "Highest valid normalized mass flow rate";
  parameter Real scaM_flow = 1 
    "Factor used to scale the mass flow rate of the fan (used for quickly adjusting fan size)";
  parameter Real scaDp = 1 
    "Factor used to scale the pressure increase of the fan (used for quickly adjusting fan size)";

  Real pNor(min=0) "Normalized pressure";
  Real mNor_flow(start=mNorMax_flow) "Normalized mass flow rate";
  Real etaSha(min=0, max=1) "Efficiency, flow work divided by shaft power";
  Modelica.SIunits.Power PSha "Power input at shaft";

  Medium.Density rho "Medium density";
protected 
  parameter Real pNorMin1(fixed=false) 
    "Normalized pressure, used to test slope of polynomial outside [xMin, xMax]";
  parameter Real pNorMin2(fixed=false) 
    "Normalized pressure, used to test slope of polynomial outside [xMin, xMax]";
  parameter Real pNorMax1(fixed=false) 
    "Normalized pressure, used to test slope of polynomial outside [xMin, xMax]";
  parameter Real pNorMax2(fixed=false) 
    "Normalized pressure, used to test slope of polynomial outside [xMin, xMax]";

initial equation 
 // check slope of polynomial outside the domain [mNorMin_flow, mNorMax_flow]
 pNorMin1 = Buildings.Fluid.Utilities.extendedPolynomial(
                                        c=a, x=mNorMin_flow/2, xMin=mNorMin_flow, xMax=mNorMax_flow);
 pNorMin2 = Buildings.Fluid.Utilities.extendedPolynomial(
                                        c=a, x=mNorMin_flow, xMin=mNorMin_flow, xMax=mNorMax_flow);
 pNorMax1 = Buildings.Fluid.Utilities.extendedPolynomial(
                                        c=a, x=mNorMax_flow, xMin=mNorMin_flow, xMax=mNorMax_flow);
 pNorMax2 = Buildings.Fluid.Utilities.extendedPolynomial(
                                        c=a, x=mNorMax_flow*2, xMin=mNorMin_flow, xMax=mNorMax_flow);
 assert(pNorMin1>pNorMin2,
    "Slope of pump pressure polynomial is non-negative for mNor_flow < mNorMin_flow. Check parameter a.");
 assert(pNorMax1>pNorMax2,
    "Slope of pump pressure polynomial is non-negative for mNorMax_flow < mNor_flow. Check parameter a.");

equation 
  // For computing the density, we assume that the fan operates in the design flow direction.
  rho = Medium.density(
     Medium.setState_phX(port_a.p, inStream(port_a.h_outflow), inStream(port_a.Xi_outflow)));

  -dp = scaDp     * pNor      * rho * D*D   * N_in * N_in;
  m_flow = scaM_flow * mNor_flow * rho * D*D*D * N_in;
  pNor = Buildings.Fluid.Utilities.extendedPolynomial(
                                        c=a, x=mNor_flow, xMin=mNorMin_flow, xMax=mNorMax_flow);
  etaSha = max(0.1, Buildings.Fluid.Utilities.polynomial(
                                                      c=b, x=mNor_flow));
  etaSha * PSha = -dp * m_flow / rho; // dp<0 and m_flow>0 for normal operation

  // Energy balance (no storage, no heat loss/gain)
  PSha = -m_flow*(port_a.h_outflow-inStream(port_b.h_outflow));
  PSha = m_flow*(port_b.h_outflow-inStream(port_a.h_outflow));

  // Mass balance (no storage)
  port_a.m_flow + port_b.m_flow = 0;

  // 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 FlowMachinePolynomial;

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