Buildings.Fluid.Movers

Information

Package Content

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

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

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]
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
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		Characteristics.constantEffi...	Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiency		Characteristics.constantEffi...	Efficiency vs. normalized volume flow rate
replaceable function flowCharacteristic		Buildings.Fluid.Movers.BaseC...	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		Characteristics.quadraticPow...	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_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	y	Constant normalized rotational speed
Characteristics
replaceable function flowCharacteristic		Total 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

Information

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

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]
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
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		Characteristics.constantEffi...	Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiency		Characteristics.constantEffi...	Efficiency vs. normalized volume flow rate
replaceable function flowCharacteristic		Characteristics.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		Characteristics.quadraticPow...	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_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	Nrpm	Prescribed 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

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

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)
MassFlowRate	m_flow_max	m_flow_nominal	Maximum mass flow rate (at zero head) [kg/s]
Boolean	control_m_flow	false	= 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	motorCooledByFluid	true	If true, then motor heat is added to fluid stream
replaceable function motorEfficiency		Characteristics.constantEffi...	Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiency		Characteristics.constantEffi...	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_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

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

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

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)
MassFlowRate	m_flow_max	m_flow_nominal	Maximum mass flow rate (at zero head) [kg/s]
Boolean	control_m_flow	true	= 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	motorCooledByFluid	true	If true, then motor heat is added to fluid stream
replaceable function motorEfficiency		Characteristics.constantEffi...	Efficiency vs. normalized volume flow rate
replaceable function hydraulicEfficiency		Characteristics.constantEffi...	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_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

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

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

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Length	D		Diameter [m]
Real	a[:]		Polynomial coefficients for pressure=p(mNor_flow)
Real	b[:]		Polynomial coefficients for etaSha=p(mNor_flow)
Real	mNorMin_flow		Lowest valid normalized mass flow rate
Real	mNorMax_flow		Highest valid normalized mass flow rate
Real	scaM_flow	1	Factor used to scale the mass flow rate of the fan (used for quickly adjusting fan size)
Real	scaDp	1	Factor used to scale the pressure increase of the fan (used for quickly adjusting fan size)
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)
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	false	= true, if actual temperature at port is computed (may lead to events)

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	N_in	Prescribed 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;