modelPartialPumpParallel

Partial model for pump parallel

Extends from Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model with two ports and declaration of quantities that are used by many models), Buildings.Fluid.Actuators.BaseClasses.ValveParameters (Model with parameters for valves).

Information

Partial model for num parallel pumps, each with an isolation valve to avoid recirculation.

Parameters

Type	Name	Default	Description
Buildings.Fluid.Movers.Data.Generic[num]	per
Boolean	homotopyInitialization	true	= true, use homotopy method
Integer	num	2	The number of pumps
Real	threshold	0.05	Hysteresis threshold
Assumptions
Boolean	allowFlowReversal (from PartialTwoPort)	true	= false to simplify equations, assuming, but not enforcing, no flow reversal
Nominal condition
Modelica.Units.SI.MassFlowRate	m_flow_nominal (from PartialTwoPortInterface)		Nominal mass flow rate
Modelica.Units.SI.PressureDifference	dpValve_nominal (from ValveParameters)		Nominal pressure drop of fully open valve, used if CvData=Buildings.Fluid.Types.CvTypes.OpPoint
Advanced
Modelica.Units.SI.MassFlowRate	m_flow_small (from PartialTwoPortInterface)	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow
Advanced › Diagnostics
Boolean	show_T (from PartialTwoPortInterface)	false	= true, if actual temperature at port is computed
Flow Coefficient
Buildings.Fluid.Types.CvTypes	CvData (from ValveParameters)	Buildings.Fluid.Types.CvTypes.OpPoint	Selection of flow coefficient
Real	Kv (from ValveParameters)		Kv (metric) flow coefficient [m3/h/(bar)^(1/2)]
Real	Cv (from ValveParameters)		Cv (US) flow coefficient [USG/min/(psi)^(1/2)]
Modelica.Units.SI.Area	Av (from ValveParameters)		Av (metric) flow coefficient
Pressure-flow linearization
Real	deltaM (from ValveParameters)	0.02	Fraction of nominal flow rate where linearization starts, if y=1
Advanced › Nominal condition
Modelica.Units.SI.Density	rhoStd (from ValveParameters)		Inlet density for which valve coefficients are defined
Pump
Boolean	addPowerToMedium	false	Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations)
Dynamics › Pump
Modelica.Units.SI.Time	tau	1	Time constant at nominal flow (if energyDynamics <> SteadyState)
Boolean	use_riseTime	true	Set to true to continuously change motor speed
Modelica.Units.SI.Time	riseTime	30	Time needed to change motor speed
Modelica.Blocks.Types.Init	init	Modelica.Blocks.Types.Init.InitialOutput	Type of initialization (no init/steady state/initial state/initial output)
Real	yPump_start	fill(0, num)	Initial value of pump signals
Dynamics › Valve
Boolean	use_strokeTime	true	Set to true to continuously change valve position
Modelica.Units.SI.Time	strokeTime	riseTime	Time needed to open or close valve
Real	yValve_start	fill(1, num)	Initial value of valve signals
Two-way valve
Real	l	0.0001	Valve leakage, l=Kv(y=0)/Kv(y=1)
Dynamics › Conservation equations
Modelica.Fluid.Types.Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamics.DynamicFreeInitial	Type of energy balance: dynamic (3 initialization options) or steady state
Initialization
Medium.AbsolutePressure	p_start	Medium.p_default	Start value of pressure
Medium.Temperature	T_start	Medium.T_default	Start value of temperature
Medium.MassFraction[Medium.nX]	X_start	Medium.X_default	Start value of mass fractions m_i/m
Medium.ExtraProperty[Medium.nC]	C_start	fill(0, Medium.nC)	Start value of trace substances
Medium.ExtraProperty[Medium.nC]	C_nominal	fill(1E-2, Medium.nC)	Nominal value of trace substances. (Set to typical order of magnitude.)
Flow resistance
Boolean	from_dp	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance	false	= true, use linear relation between m_flow and dp for any flow rate

Connectors

Type	Name	Description
Modelica.Fluid.Interfaces.FluidPort_a	port_a (from PartialTwoPort)	Fluid connector a (positive design flow direction is from port_a to port_b)
Modelica.Fluid.Interfaces.FluidPort_b	port_b (from PartialTwoPort)	Fluid connector b (positive design flow direction is from port_a to port_b)
Modelica.Blocks.Interfaces.RealInput[num]	u	Continuous input signal for the flow machine
Modelica.Blocks.Interfaces.RealOutput[num]	P	Electrical power consumed by the pumps

Components

Type	Name	Default	Description
Modelica.Units.SI.MassFlowRate	m_flow (from PartialTwoPortInterface)	port_a.m_flow	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction)
Modelica.Units.SI.PressureDifference	dp (from PartialTwoPortInterface)	port_a.p - port_b.p	Pressure difference between port_a and port_b
Medium.ThermodynamicState	sta_a (from PartialTwoPortInterface)	if allowFlowReversal then Medium.setState_phX(port_a.p, noEvent(actualStream(port_a.h_outflow)), noEvent(actualStream(port_a.Xi_outflow))) else Medium.setState_phX(port_a.p, noEvent(inStream(port_a.h_outflow)), noEvent(inStream(port_a.Xi_outflow)))	Medium properties in port_a
Medium.ThermodynamicState	sta_b (from PartialTwoPortInterface)	if allowFlowReversal then Medium.setState_phX(port_b.p, noEvent(actualStream(port_b.h_outflow)), noEvent(actualStream(port_b.Xi_outflow))) else Medium.setState_phX(port_b.p, noEvent(port_b.h_outflow), noEvent(port_b.Xi_outflow))	Medium properties in port_b
Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine[num]	pum
Buildings.Fluid.Actuators.Valves.TwoWayLinear[num]	val		Isolation valves
Buildings.Controls.OBC.CDL.Reals.Hysteresis[num]	hys		Hysteresis for isolation valves
Buildings.Controls.OBC.CDL.Reals.Switch[num]	swi		Switch to enable pump only once the valve is commanded open

Revisions

June 17, 2026, by Michael Wetter:
Updated implementation to allow a flow coefficient n that is different from 2. This allows use of the model for not fully turbulent flow.
This is for Buildings, #4620.
March 1, 2023, by Michael Wetter:
Changed constants from 0 to 0.0 and 1 to 1.0.
This is for #3267.
November 16, 2022, by Michael Wetter:
Improved sequence to avoid switching pump on when the valve is commanded off.
November 15, 2022, by Michael Wetter:
Set initial state of valve to be open, and changed rise time of valve to be the same as pump.
This is for IBPSA, issue 1659.
March 3, 2022, by Michael Wetter:
Moved massDynamics to Advanced tab and added assertion for correct combination of energy and mass dynamics.
This is for IBPSA, issue 1542.
April 14, 2020, by Michael Wetter:
Changed homotopyInitialization to a constant.
This is for IBPSA, Buildings, #1341.
September 2, 2017, by Michael Wetter:
Removed sign with hysteresis to avoid chattering.
June 30, 2017, by Yangyang Fu:
First implementation.