Buildings.DHC.Plants.Combined.Subsystems.BaseClasses
Package with base classes
Information
This package contains base classes that are used to construct subsystem models.
Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).
Package Content
| Name | Description |
|---|---|
 MultipleValves
|
Parallel arrangement of identical two-way modulating valves |
 PartialMultiplePumps
|
Base class for modeling multiple identical pumps in parallel |
 PassThroughFluid
|
Direct fluid pass-through |
Buildings.DHC.Plants.Combined.Subsystems.BaseClasses.MultipleValves
Parallel arrangement of identical two-way modulating valves
Information
This model represents a set of control valves piped in parallel. An optional fixed resistance may be included in series with each valve.
Extends from Buildings.Fluid.Interfaces.LumpedVolumeDeclarations (Declarations for lumped volumes), Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model with two ports and declaration of quantities that are used by many models).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Integer | nUni | Number of units (branches in the network) | |
| TwoWayEqualPercentage | val[nUni] | redeclare Fluid.Actuators.Va... | Modulating valve |
| Nominal condition | |||
| MassFlowRate | mUni_flow_nominal | Nominal mass flow rate (each unit) [kg/s] | |
| PressureDifference | dpValve_nominal | Nominal pressure drop of fully open valve (each unit) [Pa] | |
| PressureDifference | dpFixed_nominal | 0 | Pressure drop of pipe and other resistances that are in series (each unit) [Pa] |
| Dynamics | |||
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Real | mSenFac | 1 | Factor for scaling the sensible thermal mass of the volume |
| Filtered opening | |||
| Boolean | use_inputFilter | true | Opening is filtered with a 2nd order CriticalDamping filter |
| Time | riseTime | 120 | Rise time of the filter (time to reach 99.6 % of an opening step) [s] |
| Init | init | Modelica.Blocks.Types.Init.I... | Type of initialization (no init/steady state/initial state/initial output) |
| Real | y_start | 1 | Initial position of actuator |
| Advanced | |||
| Dynamics | |||
| Dynamics | massDynamics | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state, must be steady state if energyDynamics is steady state |
| MassFlowRate | m_flow_small | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| Boolean | from_dp | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearized | false | = true, use linear relation between m_flow and dp for any flow rate |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at port is computed |
| Initialization | |||
| AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa] |
| Temperature | T_start | Medium.T_default | Start value of temperature [K] |
| 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 |
| ExtraProperty | C_nominal[Medium.nC] | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
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 | y[nUni] | Valve commanded position |
| output RealOutput | y_actual[nUni] | Valve returned position |
Modelica definition
model MultipleValves
"Parallel arrangement of identical two-way modulating valves"
extends Buildings.Fluid.Interfaces.LumpedVolumeDeclarations(
final massDynamics=energyDynamics,
final mSenFac=1);
extends Buildings.Fluid.Interfaces.PartialTwoPortInterface(
final m_flow_nominal(final min=Modelica.Constants.small)=nUni*mUni_flow_nominal,
show_T=false,
port_a(
h_outflow(start=h_outflow_start)),
port_b(
h_outflow(start=h_outflow_start),
p(start=p_start),
final m_flow(max = if allowFlowReversal then +Modelica.Constants.inf else 0)));
parameter Integer nUni(
final min=1,
start=1)
"Number of units (branches in the network)";
parameter Modelica.Units.SI.MassFlowRate mUni_flow_nominal(
final min=Modelica.Constants.small)
"Nominal mass flow rate (each unit)";
parameter Modelica.Units.SI.PressureDifference dpValve_nominal(
displayUnit="Pa",
min=0)
"Nominal pressure drop of fully open valve (each unit)";
parameter Modelica.Units.SI.PressureDifference dpFixed_nominal(
displayUnit="Pa",
min=0) = 0
"Pressure drop of pipe and other resistances that are in series (each unit)";
parameter Boolean use_inputFilter=true
"Opening is filtered with a 2nd order CriticalDamping filter";
parameter Modelica.Units.SI.Time riseTime=120
"Rise time of the filter (time to reach 99.6 % of an opening step)";
parameter Modelica.Blocks.Types.Init init=Modelica.Blocks.Types.Init.InitialOutput
"Type of initialization (no init/steady state/initial state/initial output)";
parameter Real y_start=1 "Initial position of actuator";
parameter Boolean from_dp = false
"= true, use m_flow = f(dp) else dp = f(m_flow)";
parameter Boolean linearized = false
"= true, use linear relation between m_flow and dp for any flow rate";
Buildings.Controls.OBC.CDL.Interfaces.RealInput y[nUni]
"Valve commanded position";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput y_actual[nUni]
"Valve returned position";
Fluid.FixedResistances.Junction junInl[nUni](
redeclare each final package Medium=Medium,
each final m_flow_nominal=m_flow_nominal * {1,-1,-1},
each final dp_nominal=fill(0,3),
each final energyDynamics=energyDynamics,
each final portFlowDirection_1=if allowFlowReversal then
Modelica.Fluid.Types.PortFlowDirection.Bidirectional else
Modelica.Fluid.Types.PortFlowDirection.Entering,
each final portFlowDirection_2=if allowFlowReversal then
Modelica.Fluid.Types.PortFlowDirection.Bidirectional else
Modelica.Fluid.Types.PortFlowDirection.Leaving,
each final portFlowDirection_3=if allowFlowReversal then
Modelica.Fluid.Types.PortFlowDirection.Bidirectional else
Modelica.Fluid.Types.PortFlowDirection.Leaving)
"Fluid junction";
Fluid.FixedResistances.Junction junOut[nUni](
redeclare each final package Medium=Medium,
each final m_flow_nominal=m_flow_nominal * {1,-1,1},
each final dp_nominal=fill(0,3),
each final energyDynamics=energyDynamics,
each final portFlowDirection_1=if allowFlowReversal then
Modelica.Fluid.Types.PortFlowDirection.Bidirectional else
Modelica.Fluid.Types.PortFlowDirection.Entering,
each final portFlowDirection_2=if allowFlowReversal then
Modelica.Fluid.Types.PortFlowDirection.Bidirectional else
Modelica.Fluid.Types.PortFlowDirection.Leaving,
each final portFlowDirection_3=if allowFlowReversal then
Modelica.Fluid.Types.PortFlowDirection.Bidirectional else
Modelica.Fluid.Types.PortFlowDirection.Entering)
"Fluid junction";
replaceable Fluid.Actuators.Valves.TwoWayEqualPercentage val[nUni]
constrainedby Buildings.Fluid.Actuators.BaseClasses.PartialTwoWayValveKv(
redeclare each final package Medium = Medium,
each final from_dp=from_dp,
each final linearized=linearized,
each final CvData=Buildings.Fluid.Types.CvTypes.OpPoint,
each final m_flow_nominal=mUni_flow_nominal,
each final dpValve_nominal=dpValve_nominal,
each final dpFixed_nominal=dpFixed_nominal,
each final allowFlowReversal=allowFlowReversal,
each final use_inputFilter=use_inputFilter,
each final riseTime=riseTime,
each final init=init,
each final y_start=y_start)
"Modulating valve";
protected
final parameter Medium.ThermodynamicState sta_start=Medium.setState_pTX(
T=T_start,
p=p_start,
X=X_start)
"Medium state at start values";
final parameter Modelica.Units.SI.SpecificEnthalpy h_outflow_start=
Medium.specificEnthalpy(sta_start)
"Start value for outflowing enthalpy";
equation
if nUni > 1 then
for i in 1:(nUni - 1) loop
connect(junOut[i].port_1, junOut[i+1].port_2);
connect(junInl[i].port_2, junInl[i+1].port_1);
end for;
end if;
connect(junInl.port_3, val.port_a);
connect(val.port_b, junOut.port_3);
connect(junOut[1].port_2, port_b);
connect(port_a, junInl[1].port_1);
connect(val.y_actual, y_actual);
connect(y, val.y);
end MultipleValves;
Buildings.DHC.Plants.Combined.Subsystems.BaseClasses.PartialMultiplePumps
Base class for modeling multiple identical pumps in parallel
Information
This base class represents multiple identical pumps that are piped in parallel. An optional check valve in series with each pump is included. This class is used to construct the various multiple-pump models within Buildings.DHC.Plants.Combined.Subsystems.
Details
In a parallel arrangement, all operating units have the same operating point. This allows modeling the multiple pumps with a single instance of any class derived from Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine. Hydronics are resolved with mass flow rate multiplier components.
Extends from Buildings.Fluid.Interfaces.LumpedVolumeDeclarations (Declarations for lumped volumes), Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model with two ports and declaration of quantities that are used by many models).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Integer | nPum | Number of pumps | |
| Boolean | have_var | true | Set to true for variable speed pumps, false for constant speed |
| Boolean | have_valve | true | Set to true for inline check valve |
| Generic | per | redeclare parameter Fluid.Mo... | Pump parameters |
| SpeedControlled_y | pum | redeclare Fluid.Movers.Speed... | Pump |
| Nominal condition | |||
| MassFlowRate | mPum_flow_nominal | Design mass flow rate (each pump) [kg/s] | |
| PressureDifference | dpPum_nominal | Design head (each pump) [Pa] | |
| PressureDifference | dpValve_nominal | 10000 | Pressure drop of check valve fully open [Pa] |
| Dynamics | |||
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Real | mSenFac | 1 | Factor for scaling the sensible thermal mass of the volume |
| Nominal condition | |||
| Time | tau | 1 | Time constant of fluid volume for nominal flow, used if energy or mass balance is dynamic [s] |
| Filtered speed | |||
| Boolean | use_inputFilter | true | = true, if speed is filtered with a 2nd order CriticalDamping filter |
| Time | riseTime | 30 | Rise time of the filter (time to reach 99.6 % of the speed) [s] |
| Init | init | Modelica.Blocks.Types.Init.I... | Type of initialization (no init/steady state/initial state/initial output) |
| Advanced | |||
| Dynamics | |||
| Dynamics | massDynamics | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state, must be steady state if energyDynamics is steady state |
| MassFlowRate | m_flow_small | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at port is computed |
| Initialization | |||
| AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa] |
| Temperature | T_start | Medium.T_default | Start value of temperature [K] |
| 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 |
| ExtraProperty | C_nominal[Medium.nC] | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
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 BooleanInput | y1[nPum] | Start signal (VFD Run or motor starter contact) |
| output RealOutput | P | Total power (all pumps) [W] |
| output BooleanOutput | y1_actual[nPum] | Pump status |
Modelica definition
partial model PartialMultiplePumps
"Base class for modeling multiple identical pumps in parallel"
extends Buildings.Fluid.Interfaces.LumpedVolumeDeclarations(
final massDynamics=energyDynamics,
final mSenFac=1);
extends Buildings.Fluid.Interfaces.PartialTwoPortInterface(
final m_flow_nominal(final min=Modelica.Constants.small)=nPum * mPum_flow_nominal,
show_T=false,
port_a(
h_outflow(start=h_outflow_start)),
port_b(
h_outflow(start=h_outflow_start),
p(start=p_start),
final m_flow(max = if allowFlowReversal then +Modelica.Constants.inf else 0)));
parameter Integer nPum(
final min=1,
start=1)
"Number of pumps";
parameter Boolean have_var = true
"Set to true for variable speed pumps, false for constant speed";
parameter Boolean have_valve = true
"Set to true for inline check valve";
parameter Modelica.Units.SI.MassFlowRate mPum_flow_nominal
"Design mass flow rate (each pump)";
parameter Modelica.Units.SI.PressureDifference dpPum_nominal(
displayUnit="Pa")
"Design head (each pump)";
parameter Modelica.Units.SI.PressureDifference dpValve_nominal(
displayUnit="Pa")=10000
"Pressure drop of check valve fully open";
replaceable parameter Fluid.Movers.Data.Generic per
constrainedby Buildings.Fluid.Movers.Data.Generic(
pressure(
V_flow={0, 1, 2} * mPum_flow_nominal / rho_default,
dp={1.14, 1, 0.42} * dpPum_nominal),
motorCooledByFluid=false) "Pump parameters";
parameter Modelica.Units.SI.Time tau=1
"Time constant of fluid volume for nominal flow, used if energy or mass balance is dynamic";
// Classes used to implement the filtered speed
parameter Boolean use_inputFilter=true
"= true, if speed is filtered with a 2nd order CriticalDamping filter";
parameter Modelica.Units.SI.Time riseTime=30
"Rise time of the filter (time to reach 99.6 % of the speed)";
parameter Modelica.Blocks.Types.Init init=Modelica.Blocks.Types.Init.InitialOutput
"Type of initialization (no init/steady state/initial state/initial output)";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput y1[nPum]
"Start signal (VFD Run or motor starter contact)";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput P(final unit="W")
"Total power (all pumps)";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1_actual[nPum]
"Pump status";
Fluid.BaseClasses.MassFlowRateMultiplier mulOut(
redeclare final package Medium=Medium,
final use_input=true)
"Flow rate multiplier";
Fluid.BaseClasses.MassFlowRateMultiplier mulInl(
redeclare final package Medium=Medium,
final use_input=true)
"Flow rate multiplier";
replaceable Fluid.Movers.SpeedControlled_y pum
constrainedby Buildings.Fluid.Movers.BaseClasses.PartialFlowMachine(
redeclare final package Medium=Medium,
final tau=tau,
final show_T=show_T,
final allowFlowReversal=allowFlowReversal,
final energyDynamics=energyDynamics,
final use_inputFilter=use_inputFilter,
final riseTime=riseTime,
final init=init,
final per=per,
addPowerToMedium=false) "Pump";
Buildings.Templates.Components.Controls.MultipleCommands com(final nUni=nPum)
"Convert command signal";
Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea
"Convert to real";
Buildings.Controls.OBC.CDL.Reals.Multiply mul "Compute total power";
Buildings.Controls.OBC.CDL.Reals.Multiply inp
"Compute pump input signal";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant cst
if not have_var "Constant setpoint";
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold isOpe(t=1E-2, h=0.5E-2)
"Evaluate if pump is operating";
Fluid.FixedResistances.CheckValve cheVal(
redeclare final package Medium=Medium,
final m_flow_nominal=mPum_flow_nominal,
final dpValve_nominal=dpValve_nominal,
final show_T=show_T,
final allowFlowReversal=allowFlowReversal) if have_valve
"Check valve (optional)";
Buildings.DHC.Plants.Combined.Subsystems.BaseClasses.PassThroughFluid pas(
redeclare final package Medium=Medium,
final allowFlowReversal=allowFlowReversal) if not have_valve
"Direct fluid pass-through (case without check valve)";
Buildings.Controls.OBC.CDL.Routing.BooleanScalarReplicator rep(
final nout=nPum)
"Replicate";
Buildings.Controls.OBC.CDL.Logical.Pre preY1[nPum]
"Left limit of signal avoiding direct feedback of status to controller";
protected
parameter Medium.ThermodynamicState sta_default=Medium.setState_pTX(
T=Medium.T_default,
p=Medium.p_default,
X=Medium.X_default)
"State of the medium at the medium default properties";
parameter Modelica.Units.SI.Density rho_default=Medium.density(sta_default)
"Density at the medium default properties";
final parameter Medium.ThermodynamicState sta_start=Medium.setState_pTX(
T=T_start,
p=p_start,
X=X_start)
"Medium state at start values";
final parameter Modelica.Units.SI.SpecificEnthalpy h_outflow_start=
Medium.specificEnthalpy(sta_start)
"Start value for outflowing enthalpy";
equation
connect(mulOut.port_b, port_b);
connect(port_a, mulInl.port_a);
connect(mulOut.uInv, mulInl.u);
connect(mulInl.port_b, pum.port_a);
connect(com.nUniOnBou, mulOut.u);
connect(com.y1One, booToRea.u);
connect(mul.y, P);
connect(com.nUniOn, mul.u1);
connect(pum.P, mul.u2);
connect(pum.port_b, cheVal.port_a);
connect(cheVal.port_b, mulOut.port_a);
connect(cst.y, inp.u1);
connect(booToRea.y, inp.u2);
connect(pum.port_b, pas.port_a);
connect(pas.port_b, mulOut.port_a);
connect(pum.y_actual, isOpe.u);
connect(isOpe.y, rep.u);
connect(y1, preY1.u);
connect(preY1.y, com.y1);
connect(rep.y, y1_actual);
end PartialMultiplePumps;
Buildings.DHC.Plants.Combined.Subsystems.BaseClasses.PassThroughFluid
Direct fluid pass-through
Information
This is a model of a direct fluid pass-through used for templating purposes.
Extends from Buildings.Fluid.Interfaces.PartialTwoPort (Partial component with two ports).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
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) |
Modelica definition
model PassThroughFluid "Direct fluid pass-through"
extends Buildings.Fluid.Interfaces.PartialTwoPort;
equation
connect(port_a, port_b);
end PassThroughFluid;