Buildings.Fluid.Movers.BaseClasses

Base classes used in the Machines package (only of interest to build new component models)

Information

Extends from Modelica.Fluid.Icons.BaseClassLibrary (Icon for library).

Package Content

Name Description

Characteristics Functions for fan or pump characteristics

ControlledFlowMachine Partial model for fan or pump with ideally controlled mass flow rate or head as input signal

PrescribedFlowMachine Partial model for fan or pump with speed (y or Nrpm) as input signal

PartialFlowMachine Partial model to interface fan or pump models with the medium

FlowMachineInterface Partial model with performance curves for fans or pumps

IdealSource Base class for pressure and mass flow source with optional power input

PowerInterface Partial model to compute power draw and heat dissipation of fans and pumps

Name	Description
Characteristics	Functions for fan or pump characteristics
ControlledFlowMachine	Partial model for fan or pump with ideally controlled mass flow rate or head as input signal
PrescribedFlowMachine	Partial model for fan or pump with speed (y or Nrpm) as input signal
PartialFlowMachine	Partial model to interface fan or pump models with the medium
FlowMachineInterface	Partial model with performance curves for fans or pumps
IdealSource	Base class for pressure and mass flow source with optional power input
PowerInterface	Partial model to compute power draw and heat dissipation of fans and pumps

Buildings.Fluid.Movers.BaseClasses.ControlledFlowMachine

Partial model for fan or pump with ideally controlled mass flow rate or head as input signal

Buildings.Fluid.Movers.BaseClasses.ControlledFlowMachine

Information

This model describes a fan or pump that takes as an input the head or the mass flow rate.

Extends from Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine (Partial model to interface fan or pump models with the medium), Buildings.Fluid.Movers.BaseClasses.PowerInterface (Partial model to compute power draw and heat dissipation of fans and pumps).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Boolean addPowerToMedium true Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)

Density rho_nominal Medium.density(sta_nominal) Nominal fluid density [kg/m3]

MassFlowRate m_flow_max m_flow_nominal Maximum mass flow rate (at zero head) [kg/s]

Boolean control_m_flow = false to control head instead of m_flow

Nominal condition

MassFlowRate m_flow_nominal Nominal mass flow rate [kg/s]

Initialization

MassFlowRate m_flow.start 0 Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]

Pressure dp.start 0 Pressure difference between port_a and port_b [Pa]

Real r_V.start 1 Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)

Characteristics

Boolean use_powerCharacteristic false Use powerCharacteristic (vs. efficiencyCharacteristic)

Boolean motorCooledByFluid true If true, then motor heat is added to fluid stream

replaceable function motorEfficiency Buildings.Fluid.Movers.BaseC... Efficiency vs. normalized volume flow rate

replaceable function hydraulicEfficiency Buildings.Fluid.Movers.BaseC... Efficiency vs. normalized volume flow rate

Assumptions

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

Dynamics

Boolean dynamicBalance true Set to true to use a dynamic balance, which often leads to smaller systems of equations

Dynamics energyDynamics Modelica.Fluid.Types.Dynamic... Formulation of energy balance (used if dynamicBalance=true)

Time tau 1 Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal Small mass flow rate for regularization of zero flow [kg/s]

Diagnostics

Boolean show_V_flow true = true, if volume flow rate at inflowing port is computed

Boolean show_T true = true, if actual temperature at port is computed (may lead to events)

Initialization

Boolean use_T_start true = true, use T_start, otherwise h_start

Temperature T_start if use_T_start then system.T... Start value of temperature [K]

SpecificEnthalpy h_start if use_T_start then Medium.s... Start value of inlet specific enthalpy [J/kg]

MassFraction X_start[Medium.nX] Medium.X_default Start value of mass fractions m_i/m [kg/kg]

ExtraProperty C_start[Medium.nC] fill(0, Medium.nC) Start value of trace substances

Pressure p_start Medium.p_default Start value of inlet pressure [Pa]

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Boolean	addPowerToMedium	true	Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Density	rho_nominal	Medium.density(sta_nominal)	Nominal fluid density [kg/m3]
MassFlowRate	m_flow_max	m_flow_nominal	Maximum mass flow rate (at zero head) [kg/s]
Boolean	control_m_flow		= false to control head instead of m_flow
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate [kg/s]
Initialization
MassFlowRate	m_flow.start	0	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure	dp.start	0	Pressure difference between port_a and port_b [Pa]
Real	r_V.start	1	Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)
Characteristics
Boolean	use_powerCharacteristic	false	Use powerCharacteristic (vs. efficiencyCharacteristic)
Boolean	motorCooledByFluid	true	If true, then motor heat is added to fluid stream
replaceable function motorEfficiency	Buildings.Fluid.Movers.BaseC...	Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiency	Buildings.Fluid.Movers.BaseC...	Efficiency vs. normalized volume flow rate
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
Boolean	dynamicBalance	true	Set to true to use a dynamic balance, which often leads to smaller systems of equations
Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamic...	Formulation of energy balance (used if dynamicBalance=true)
Time	tau	1	Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean	show_V_flow	true	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	true	= true, if actual temperature at port is computed (may lead to events)
Initialization
Boolean	use_T_start	true	= true, use T_start, otherwise h_start
Temperature	T_start	if use_T_start then system.T...	Start value of temperature [K]
SpecificEnthalpy	h_start	if use_T_start then Medium.s...	Start value of inlet specific enthalpy [J/kg]
MassFraction	X_start[Medium.nX]	Medium.X_default	Start value of mass fractions m_i/m [kg/kg]
ExtraProperty	C_start[Medium.nC]	fill(0, Medium.nC)	Start value of trace substances
Pressure	p_start	Medium.p_default	Start value of inlet pressure [Pa]

Connectors

Type Name Description

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

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

HeatPort_a heatPort

input RealInput m_flow_in Prescribed mass flow rate

input RealInput dp_in Prescribed outlet pressure

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
HeatPort_a	heatPort
input RealInput	m_flow_in	Prescribed mass flow rate
input RealInput	dp_in	Prescribed outlet pressure

Modelica definition

model ControlledFlowMachine 
  "Partial model for fan or pump with ideally controlled mass flow rate or head as input signal"
  extends Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine(
   final show_V_flow = true,
   souSta(final control_m_flow=control_m_flow),
   souDyn(final control_m_flow=control_m_flow));

  extends Buildings.Fluid.Movers.BaseClasses.PowerInterface(
     final use_powerCharacteristic = false,
     final rho_nominal = Medium.density(sta_nominal));

  parameter Medium.MassFlowRate m_flow_nominal 
    "Nominal mass flow rate, used as flow rate if control_m_flow";
  parameter Modelica.SIunits.MassFlowRate m_flow_max = m_flow_nominal 
    "Maximum mass flow rate (at zero head)";
  // what to control
  constant Boolean control_m_flow "= false to control head instead of m_flow";

  Modelica.Blocks.Interfaces.RealInput m_flow_in if control_m_flow 
    "Prescribed mass flow rate";
  Modelica.Blocks.Interfaces.RealInput dp_in if not control_m_flow 
    "Prescribed outlet pressure";

protected 
  final parameter Medium.AbsolutePressure p_a_nominal(displayUnit="Pa") = Medium.p_default 
    "Nominal inlet pressure for predefined fan or pump characteristics";
  parameter Medium.ThermodynamicState sta_nominal = Medium.setState_pTX(T=T_start,
     p=p_a_nominal, X=X_start[1:Medium.nXi]);

public 
  Modelica.Blocks.Sources.RealExpression PToMedium_flow(y=Q_flow + dpMachine*
        V_in_flow) "Heat and work input into medium";
protected 
  Modelica.Blocks.Math.Gain gain(final k=-1) if not control_m_flow;
initial equation 
  V_flow_max=m_flow_max/rho_nominal;
equation 
  etaHyd = hydraulicEfficiency(r_V=r_V);
  etaMot = motorEfficiency(r_V=r_V);
  dpMachine = -dp;
  VMachine_flow = V_flow;

  connect(m_flow_in, souDyn.m_flow_in);
  connect(m_flow_in, souSta.m_flow_in);
  connect(gain.u, dp_in);
  connect(gain.y, souDyn.dp_in);
  connect(gain.y, souSta.dp_in);

  connect(PToMedium_flow.y, prePow.Q_flow);
  connect(PToMedium_flow.y, souSta.P_in);
end ControlledFlowMachine;

Buildings.Fluid.Movers.BaseClasses.PrescribedFlowMachine

Partial model for fan or pump with speed (y or Nrpm) as input signal

Buildings.Fluid.Movers.BaseClasses.PrescribedFlowMachine

Information

This is the base model for fans and pumps that take as input a control signal in the form of the pump speed Nrpm or the normalized pump speed y=Nrpm/N_nominal.

Extends from Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine (Partial model to interface fan or pump models with the medium), Buildings.Fluid.Movers.BaseClasses.FlowMachineInterface (Partial model with performance curves for fans or pumps).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Boolean addPowerToMedium true Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)

Density rho_nominal Medium.density_pTX(Medium.p_... Nominal fluid density [kg/m3]

Nominal condition

MassFlowRate m_flow_nominal Nominal mass flow rate [kg/s]

Initialization

MassFlowRate m_flow.start 0 Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]

Pressure dp.start 0 Pressure difference between port_a and port_b [Pa]

Real r_V.start 1 Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)

Real r_N.start 1 Ratio N/N_nominal [1]

Characteristics

Boolean use_powerCharacteristic false Use powerCharacteristic (vs. efficiencyCharacteristic)

Boolean motorCooledByFluid true If true, then motor heat is added to fluid stream

replaceable function motorEfficiency Buildings.Fluid.Movers.BaseC... Efficiency vs. normalized volume flow rate

replaceable function hydraulicEfficiency Buildings.Fluid.Movers.BaseC... Efficiency vs. normalized volume flow rate

replaceable function flowCharacteristic baseFlow Total pressure vs. V_flow characteristic at nominal speed

AngularVelocity_rpm N_nominal 1500 Nominal rotational speed for flow characteristic [1/min]

replaceable function powerCharacteristic Buildings.Fluid.Movers.BaseC... Power consumption vs. V_flow at nominal speed and density

Assumptions

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

Dynamics

Boolean dynamicBalance true Set to true to use a dynamic balance, which often leads to smaller systems of equations

Dynamics energyDynamics Modelica.Fluid.Types.Dynamic... Formulation of energy balance (used if dynamicBalance=true)

Time tau 1 Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal Small mass flow rate for regularization of zero flow [kg/s]

Diagnostics

Boolean show_V_flow false = true, if volume flow rate at inflowing port is computed

Boolean show_T true = true, if actual temperature at port is computed (may lead to events)

Initialization

Boolean use_T_start true = true, use T_start, otherwise h_start

Temperature T_start if use_T_start then system.T... Start value of temperature [K]

SpecificEnthalpy h_start if use_T_start then Medium.s... Start value of inlet specific enthalpy [J/kg]

MassFraction X_start[Medium.nX] Medium.X_default Start value of mass fractions m_i/m [kg/kg]

ExtraProperty C_start[Medium.nC] fill(0, Medium.nC) Start value of trace substances

Pressure p_start Medium.p_default Start value of inlet pressure [Pa]

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Boolean	addPowerToMedium	true	Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Density	rho_nominal	Medium.density_pTX(Medium.p_...	Nominal fluid density [kg/m3]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate [kg/s]
Initialization
MassFlowRate	m_flow.start	0	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure	dp.start	0	Pressure difference between port_a and port_b [Pa]
Real	r_V.start	1	Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)
Real	r_N.start	1	Ratio N/N_nominal [1]
Characteristics
Boolean	use_powerCharacteristic	false	Use powerCharacteristic (vs. efficiencyCharacteristic)
Boolean	motorCooledByFluid	true	If true, then motor heat is added to fluid stream
replaceable function motorEfficiency	Buildings.Fluid.Movers.BaseC...	Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiency	Buildings.Fluid.Movers.BaseC...	Efficiency vs. normalized volume flow rate
replaceable function flowCharacteristic	baseFlow	Total pressure vs. V_flow characteristic at nominal speed
AngularVelocity_rpm	N_nominal	1500	Nominal rotational speed for flow characteristic [1/min]
replaceable function powerCharacteristic	Buildings.Fluid.Movers.BaseC...	Power consumption vs. V_flow at nominal speed and density
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
Boolean	dynamicBalance	true	Set to true to use a dynamic balance, which often leads to smaller systems of equations
Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamic...	Formulation of energy balance (used if dynamicBalance=true)
Time	tau	1	Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean	show_V_flow	false	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	true	= true, if actual temperature at port is computed (may lead to events)
Initialization
Boolean	use_T_start	true	= true, use T_start, otherwise h_start
Temperature	T_start	if use_T_start then system.T...	Start value of temperature [K]
SpecificEnthalpy	h_start	if use_T_start then Medium.s...	Start value of inlet specific enthalpy [J/kg]
MassFraction	X_start[Medium.nX]	Medium.X_default	Start value of mass fractions m_i/m [kg/kg]
ExtraProperty	C_start[Medium.nC]	fill(0, Medium.nC)	Start value of trace substances
Pressure	p_start	Medium.p_default	Start value of inlet pressure [Pa]

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
HeatPort_a	heatPort

Modelica definition

partial model PrescribedFlowMachine 
  "Partial model for fan or pump with speed (y or Nrpm) as input signal"
  extends Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine(
      final show_V_flow = false,
      souDyn(final control_m_flow=false),
      souSta(final control_m_flow=false));

  extends Buildings.Fluid.Movers.BaseClasses.FlowMachineInterface(
    V_flow_max(start=m_flow_nominal/rho_nominal),
    final rho_nominal = Medium.density_pTX(Medium.p_default, Medium.T_default, Medium.X_default));

  // Models
protected 
  Modelica.Blocks.Sources.RealExpression dpMac(y=-dpMachine) 
    "Pressure drop of the pump or fan";
  Modelica.Blocks.Sources.RealExpression QMac_flow(y=Q_flow + dpMachine*
        V_in_flow) 
    "Heat input into the medium from the fan or pump (not including flow work)";

equation 
 VMachine_flow = V_in_flow;
 rho = rho_in;

  connect(dpMac.y, souSta.dp_in);
  connect(dpMac.y, souDyn.dp_in);

  connect(QMac_flow.y, prePow.Q_flow);
  connect(QMac_flow.y, souSta.P_in);
end PrescribedFlowMachine;

Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine

Partial model to interface fan or pump models with the medium

Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine

Information

This is the base model for fans and pumps. It provides an interface between the equations that compute head and power consumption, and the implementation of the energy and pressure balance of the fluid.

The model has two fluid streams. Depending on the value of the parameter dynamicBalance, one of the streams is removed.

The parameter addPowerToMedium determines whether any power is added to the fluid. The default is addPowerToMedium=true, and hence the outlet enthalpy is higher than the inlet enthalpy if the flow device is operating. The setting addPowerToMedium=false is physically incorrect (since the flow work, the flow friction and the fan heat do not increase the enthalpy of the medium), but this setting does in some cases lead to simpler equations.

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

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Boolean addPowerToMedium true Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)

Nominal condition

MassFlowRate m_flow_nominal Nominal mass flow rate [kg/s]

Initialization

MassFlowRate m_flow.start 0 Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]

Pressure dp.start 0 Pressure difference between port_a and port_b [Pa]

Assumptions

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

Dynamics

Boolean dynamicBalance true Set to true to use a dynamic balance, which often leads to smaller systems of equations

Dynamics energyDynamics Modelica.Fluid.Types.Dynamic... Formulation of energy balance (used if dynamicBalance=true)

Time tau 1 Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal Small mass flow rate for regularization of zero flow [kg/s]

Diagnostics

Boolean show_V_flow false = true, if volume flow rate at inflowing port is computed

Boolean show_T true = true, if actual temperature at port is computed (may lead to events)

Initialization

Boolean use_T_start true = true, use T_start, otherwise h_start

Temperature T_start if use_T_start then system.T... Start value of temperature [K]

SpecificEnthalpy h_start if use_T_start then Medium.s... Start value of inlet specific enthalpy [J/kg]

MassFraction X_start[Medium.nX] Medium.X_default Start value of mass fractions m_i/m [kg/kg]

ExtraProperty C_start[Medium.nC] fill(0, Medium.nC) Start value of trace substances

Pressure p_start Medium.p_default Start value of inlet pressure [Pa]

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Boolean	addPowerToMedium	true	Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate [kg/s]
Initialization
MassFlowRate	m_flow.start	0	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure	dp.start	0	Pressure difference between port_a and port_b [Pa]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
Boolean	dynamicBalance	true	Set to true to use a dynamic balance, which often leads to smaller systems of equations
Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamic...	Formulation of energy balance (used if dynamicBalance=true)
Time	tau	1	Time constant of fluid volume for nominal flow, used if dynamicBalance=true [s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean	show_V_flow	false	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	true	= true, if actual temperature at port is computed (may lead to events)
Initialization
Boolean	use_T_start	true	= true, use T_start, otherwise h_start
Temperature	T_start	if use_T_start then system.T...	Start value of temperature [K]
SpecificEnthalpy	h_start	if use_T_start then Medium.s...	Start value of inlet specific enthalpy [J/kg]
MassFraction	X_start[Medium.nX]	Medium.X_default	Start value of mass fractions m_i/m [kg/kg]
ExtraProperty	C_start[Medium.nC]	fill(0, Medium.nC)	Start value of trace substances
Pressure	p_start	Medium.p_default	Start value of inlet pressure [Pa]

Connectors

Type Name Description

HeatPort_a heatPort

Type	Name	Description
HeatPort_a	heatPort

Modelica definition

partial model PartialFlowMachine 
  "Partial model to interface fan or pump models with the medium"
  import Modelica.Constants;

  extends Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface(show_T=true,
    port_a(
      h_outflow(start=h_start),
      final m_flow(min = if allowFlowReversal then -Constants.inf else 0)),
    port_b(
      h_outflow(start=h_start),
      p(start=p_start),
      final m_flow(max = if allowFlowReversal then +Constants.inf else 0)));

  Delays.DelayFirstOrder vol(
    redeclare package Medium = Medium,
    tau=tau,
    energyDynamics=energyDynamics,
    massDynamics=massDynamics,
    use_T_start=use_T_start,
    T_start=T_start,
    h_start=h_start,
    X_start=X_start,
    C_start=C_start,
    m_flow_nominal=m_flow_nominal,
    use_HeatTransfer=true,
    redeclare model HeatTransfer =
        Modelica.Fluid.Vessels.BaseClasses.HeatTransfer.IdealHeatTransfer,
    nPorts=2,
    p_start=p_start) if 
       dynamicBalance "Fluid volume for dynamic model";
   parameter Boolean dynamicBalance = true 
    "Set to true to use a dynamic balance, which often leads to smaller systems of equations";

  parameter Boolean addPowerToMedium=true 
    "Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)";

  parameter Modelica.Fluid.Types.Dynamics energyDynamics=
                     Modelica.Fluid.Types.Dynamics.SteadyStateInitial 
    "Formulation of energy balance (used if dynamicBalance=true)";
  final parameter Modelica.Fluid.Types.Dynamics massDynamics=energyDynamics 
    "Formulation of mass balance (used if dynamicBalance=true)";

  parameter Modelica.SIunits.Time tau=1 
    "Time constant of fluid volume for nominal flow, used if dynamicBalance=true";

  // Parameters for initialization
  // Initialization
  parameter Boolean use_T_start=true "= true, use T_start, otherwise h_start";
  parameter Modelica.Media.Interfaces.PartialMedium.Temperature T_start=if 
      use_T_start then system.T_start else Medium.temperature_phX(
      p_start,
      h_start,
      X_start) "Start value of temperature";
  parameter Modelica.Media.Interfaces.PartialMedium.SpecificEnthalpy h_start=
      if use_T_start then Medium.specificEnthalpy_pTX(
      p_start,
      T_start,
      X_start) else Medium.h_default "Start value of inlet specific enthalpy";
  parameter Modelica.Media.Interfaces.PartialMedium.MassFraction X_start[Medium.nX]=
     Medium.X_default "Start value of mass fractions m_i/m";
  parameter Modelica.Media.Interfaces.PartialMedium.ExtraProperty C_start[
    Medium.nC]=fill(0, Medium.nC) "Start value of trace substances";
  parameter Modelica.SIunits.Pressure p_start = Medium.p_default 
    "Start value of inlet pressure";
  Modelica.SIunits.Density rho_in "Density of inflowing fluid";
  Modelica.SIunits.VolumeFlowRate V_in_flow 
    "Volume flow rate that flows into the device";
  // Models
  Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heatPort if dynamicBalance;

protected 
  IdealSource souDyn(redeclare package Medium =
                       Medium, final addPowerToMedium=false) if dynamicBalance 
    "Pressure source for dynamic model, this changes the pressure in the medium";
  Buildings.Fluid.Movers.BaseClasses.IdealSource souSta(
                            redeclare package Medium = Medium,
                            final addPowerToMedium=addPowerToMedium) if not dynamicBalance 
    "Source for static model, this changes the pressure in the medium and adds heat";
  Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow prePow if (dynamicBalance and addPowerToMedium) 
    "Prescribed power (=heat and flow work) flow for dynamic model";

equation 
  // For computing the density, we assume that the fan operates in the design flow direction.
  rho_in = Medium.density(
       Medium.setState_phX(port_a.p, inStream(port_a.h_outflow), inStream(port_a.Xi_outflow)));
  V_in_flow = m_flow/rho_in;
  connect(prePow.port, vol.heatPort);

  connect(souSta.port_b, port_b);

  connect(vol.heatPort, heatPort);
  connect(port_a, vol.ports[1]);
  connect(souDyn.port_b, port_b);
  connect(souSta.port_a, port_a);
  connect(vol.ports[2], souDyn.port_a);
end PartialFlowMachine;

Buildings.Fluid.Movers.BaseClasses.FlowMachineInterface

Partial model with performance curves for fans or pumps

Information

This is an interface that implements the functions to compute the head, power draw and efficiency of fans and pumps. It is used by the model PrescribedFlowMachine.

The nominal hydraulic characteristic (total pressure vs. volume flow rate) is given by the the replaceable function flowCharacteristic.

The fan or pump energy balance can be specified in two alternative ways:

If use_powerCharacteristic = false, the replaceable function efficiencyCharacteristic (efficiency vs. normalized volume flow rate) is used to determine the efficiency, and then the power consumption. The default is a constant efficiency of 0.8.

If use_powerCharacteristic = true, the replaceable function powerCharacteristic (power consumption vs. normalized volume flow rate at nominal conditions) is used to determine the power consumption, and then the efficiency. Use powerCharacteristic to specify a non-zero power consumption for zero flow rate.

Extends from Buildings.Fluid.Movers.BaseClasses.PowerInterface (Partial model to compute power draw and heat dissipation of fans and pumps).

Parameters

Type Name Default Description

Density rho_nominal Nominal fluid density [kg/m3]

Characteristics

Boolean use_powerCharacteristic false Use powerCharacteristic (vs. efficiencyCharacteristic)

Boolean motorCooledByFluid true If true, then motor heat is added to fluid stream

replaceable function motorEfficiency Buildings.Fluid.Movers.BaseC... Efficiency vs. normalized volume flow rate

replaceable function hydraulicEfficiency Buildings.Fluid.Movers.BaseC... Efficiency vs. normalized volume flow rate

AngularVelocity_rpm N_nominal 1500 Nominal rotational speed for flow characteristic [1/min]

Initialization

Real r_V.start 1 Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)

Type	Name	Default	Description
Density	rho_nominal		Nominal fluid density [kg/m3]
Characteristics
Boolean	use_powerCharacteristic	false	Use powerCharacteristic (vs. efficiencyCharacteristic)
Boolean	motorCooledByFluid	true	If true, then motor heat is added to fluid stream
replaceable function motorEfficiency	Buildings.Fluid.Movers.BaseC...	Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiency	Buildings.Fluid.Movers.BaseC...	Efficiency vs. normalized volume flow rate
AngularVelocity_rpm	N_nominal	1500	Nominal rotational speed for flow characteristic [1/min]
Initialization
Real	r_V.start	1	Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)

Modelica definition

partial model FlowMachineInterface 
  "Partial model with performance curves for fans or pumps"
  extends Buildings.Fluid.Movers.BaseClasses.PowerInterface;

  import Modelica.Constants;

  // Characteristics
  replaceable function flowCharacteristic =
      Buildings.Fluid.Movers.BaseClasses.Characteristics.baseFlow 
    "Total pressure vs. V_flow characteristic at nominal speed";
  parameter Modelica.SIunits.Conversions.NonSIunits.AngularVelocity_rpm
    N_nominal = 1500 "Nominal rotational speed for flow characteristic";

  replaceable function powerCharacteristic =
        Buildings.Fluid.Movers.BaseClasses.Characteristics.quadraticPower (
       V_flow_nominal={0,0,0},P_nominal={0,0,0}) 
    "Power consumption vs. V_flow at nominal speed and density";

  // Variables
  Modelica.SIunits.Density rho "Medium density";
  Modelica.SIunits.Conversions.NonSIunits.AngularVelocity_rpm N(min=0, start = N_nominal) 
    "Shaft rotational speed";
  Real r_N(min=0, start=1, unit="1") "Ratio N/N_nominal";

initial equation 
  // Equation to compute V_flow_max
  0 = flowCharacteristic(V_flow=V_flow_max, r_N=1);

equation 
  r_N = N/N_nominal;
  dpMachine = flowCharacteristic(V_flow=VMachine_flow, r_N=r_N);

  // Power consumption
  if use_powerCharacteristic then
    PEle = (rho/rho_nominal)*powerCharacteristic(V_flow=VMachine_flow, r_N=r_N);
    // In this configuration, we only now the total power consumption.
    // Hence, we assign the efficiency in equal parts to the motor and the hydraulic losses
    etaMot = sqrt(eta);
  else
    etaHyd = hydraulicEfficiency(r_V=r_V);
    etaMot = motorEfficiency(r_V=r_V);
  end if;

end FlowMachineInterface;

Buildings.Fluid.Movers.BaseClasses.IdealSource

Base class for pressure and mass flow source with optional power input

Buildings.Fluid.Movers.BaseClasses.IdealSource

Information

Model of a fictious pipe that is used as a base class for a pressure source or to prescribe a mass flow rate. Optionally, power can be added to the enthalpy balance of the medium.

Note that for fans and pumps with dynamic balance, both the heat and the flow work are added to the volume of air or water. This simplifies the equations compared to adding heat to the volume, and flow work to this model.

Extends from Modelica.Fluid.Interfaces.PartialTwoPortTransport (Partial element transporting fluid between two ports without storage of mass or energy).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Boolean addPowerToMedium Set to false to avoid any power being added to medium (may give simpler equations)

Boolean control_m_flow = false to control dp instead of m_flow

Assumptions

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

Advanced

AbsolutePressure dp_start 0.01*system.p_start Guess value of dp = port_a.p - port_b.p [Pa]

MassFlowRate m_flow_start system.m_flow_start Guess value of m_flow = port_a.m_flow [kg/s]

MassFlowRate m_flow_small system.m_flow_small Small mass flow rate for regularization of zero flow [kg/s]

Diagnostics

Boolean show_T true = true, if temperatures at port_a and port_b are computed

Boolean show_V_flow true = true, if volume flow rate at inflowing port is computed

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Boolean	addPowerToMedium		Set to false to avoid any power being added to medium (may give simpler equations)
Boolean	control_m_flow		= false to control dp instead of m_flow
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
AbsolutePressure	dp_start	0.01*system.p_start	Guess value of dp = port_a.p - port_b.p [Pa]
MassFlowRate	m_flow_start	system.m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
MassFlowRate	m_flow_small	system.m_flow_small	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean	show_T	true	= true, if temperatures at port_a and port_b are computed
Boolean	show_V_flow	true	= true, if volume flow rate at inflowing port is computed

Connectors

Type Name Description

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

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

input RealInput P_in Power added to the medium

input RealInput m_flow_in Prescribed mass flow rate

input RealInput dp_in Prescribed outlet pressure

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
input RealInput	P_in	Power added to the medium
input RealInput	m_flow_in	Prescribed mass flow rate
input RealInput	dp_in	Prescribed outlet pressure

Modelica definition

model IdealSource 
  "Base class for pressure and mass flow source with optional power input"
  extends Modelica.Fluid.Interfaces.PartialTwoPortTransport(final show_V_flow=true);
  Modelica.Blocks.Interfaces.RealInput P_in if addPowerToMedium 
    "Power added to the medium";

  parameter Boolean addPowerToMedium 
    "Set to false to avoid any power being added to medium (may give simpler equations)";

  // what to control
  parameter Boolean control_m_flow "= false to control dp instead of m_flow";
  Modelica.Blocks.Interfaces.RealInput m_flow_in if control_m_flow 
    "Prescribed mass flow rate";
  Modelica.Blocks.Interfaces.RealInput dp_in if not control_m_flow 
    "Prescribed outlet pressure";

protected 
  Modelica.Blocks.Interfaces.RealInput m_flow_internal 
    "Needed to connect to conditional connector";
  Modelica.Blocks.Interfaces.RealInput dp_internal 
    "Needed to connect to conditional connector";
  Modelica.Blocks.Interfaces.RealInput P_internal 
    "Needed to connect to conditional connector";

equation 
  // Ideal control
  if control_m_flow then
    m_flow = m_flow_internal;
    dp_internal = 0;
  else
    dp = dp_internal;
    m_flow_internal = 0;
  end if;

  if not addPowerToMedium then
    P_internal = 0;
  end if;

  connect(dp_internal, dp_in);
  connect(m_flow_internal, m_flow_in);
  connect(P_internal, P_in);

  // Energy balance (no storage)
  if addPowerToMedium then
    port_a.m_flow*port_a.h_outflow + port_b.m_flow*inStream(port_b.h_outflow) = -P_internal;
    port_b.m_flow*port_b.h_outflow + port_a.m_flow*inStream(port_a.h_outflow) = -P_internal;
  else
    port_a.h_outflow = inStream(port_b.h_outflow);
    port_b.h_outflow = inStream(port_a.h_outflow);
  end if;

end IdealSource;

Buildings.Fluid.Movers.BaseClasses.PowerInterface

Partial model to compute power draw and heat dissipation of fans and pumps

Information

This is an interface that implements the functions to compute the power draw and the heat dissipation of fans and pumps. It is used by the model Buildings.Fluid.Movers.BaseClasses.FlowMachineInterface.

If addHeatToMedium = false, then no heat will be added to the medium. This can lead to simpler equations.

Parameters

Type	Name	Default	Description
Density	rho_nominal		Nominal fluid density [kg/m3]
Characteristics
Boolean	use_powerCharacteristic	false	Use powerCharacteristic (vs. efficiencyCharacteristic)
Boolean	motorCooledByFluid	true	If true, then motor heat is added to fluid stream

Modelica definition

partial model PowerInterface 
  "Partial model to compute power draw and heat dissipation of fans and pumps"

  import Modelica.Constants;

  parameter Boolean use_powerCharacteristic = false 
    "Use powerCharacteristic (vs. efficiencyCharacteristic)";

  parameter Boolean motorCooledByFluid = true 
    "If true, then motor heat is added to fluid stream";
  replaceable function motorEfficiency =
    Buildings.Fluid.Movers.BaseClasses.Characteristics.constantEfficiency(eta_nominal = 0.7) constrainedby 
    Characteristics.baseEfficiency "Efficiency vs. normalized volume flow rate";
  replaceable function hydraulicEfficiency =
    Buildings.Fluid.Movers.BaseClasses.Characteristics.constantEfficiency(eta_nominal = 0.7) constrainedby 
    Characteristics.baseEfficiency "Efficiency vs. normalized volume flow rate";

  parameter Modelica.SIunits.Density rho_nominal "Nominal fluid density";

  Modelica.SIunits.Power PEle "Electrical power input";
  Modelica.SIunits.Power WHyd 
    "Hydraulic power input (converted to flow work and heat)";
  Modelica.SIunits.Power WFlo "Flow work";
  Modelica.SIunits.HeatFlowRate Q_flow "Heat input from fan or pump to medium";
  Real eta(min=0, max=1) "Global efficiency";
  Real etaHyd(min=0, max=1) "Hydraulic efficiency";
  Real etaMot(min=0, max=1) "Motor efficiency";

  Real r_V(start=1) 
    "Ratio V_flow/V_flow_max = V_flow/V_flow(dp=0, N=N_nominal)";

  Modelica.SIunits.Pressure dpMachine(displayUnit="Pa") "Pressure increase";
  Modelica.SIunits.VolumeFlowRate VMachine_flow "Volume flow rate";
protected 
  parameter Modelica.SIunits.VolumeFlowRate V_flow_max(fixed=false) 
    "Maximum volume flow rate";
  Modelica.SIunits.HeatFlowRate QThe_flow "Heat input into the medium";
  parameter Modelica.SIunits.VolumeFlowRate delta_V_flow = 1E-3*V_flow_max 
    "Factor used for setting heat input into medium to zero at very small flows";
equation 
  r_V = VMachine_flow/V_flow_max;

  eta    = etaHyd * etaMot;
  WFlo = eta * PEle;
  // Flow work
  WFlo   = dpMachine*VMachine_flow;
  // Hydraulic power (transmitted by shaft), etaHyd = WFlo/WHyd
  etaHyd * WHyd   = WFlo;
  // Heat input into medium
  QThe_flow +  WFlo = if motorCooledByFluid then PEle else WHyd;
  // At m_flow = 0, the solver may still obtain positive values for QThe_flow.
  // The next statement sets the heat input into the medium to zero for very small flow rates.
  Q_flow = Buildings.Utilities.Math.Functions.spliceFunction(pos=QThe_flow, neg=0,
                       x=abs(VMachine_flow)-2*delta_V_flow, deltax=delta_V_flow);

end PowerInterface;

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