Buildings.Fluid.DataCenters.CDUs.BaseClasses
Package with base classes
Information
This package contains base classes that are used to construct the classes in Buildings.Fluid.DataCenters.CDUs.
Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).
Package Content
| Name | Description |
|---|---|
 PartialCDU
|
Partial model for a CDU |
 PartialFourPort
|
Partial model with four ports |
| PartialFourPortInterface
|
Partial model with four ports and declaration of quantities that are used by CDU models |
Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialCDU
Partial model for a CDU
Information
Model of a coolant distribution unit (CDU) with built in two-way valve on the chilled water side and pump on the IT side as shown in the figure below.
The two fluid streams are separated by a heat exchanger.
On the chilled water side is a two-way valve that controls the mass flow rate to track to set point for the leaving fluid temperature that goes to the IT racks. By default, the controller is configured as a PI-controller. The valve has an equal-percentage opening characteristics. By default, the valve pressure drop is set to the same value as the heat exchanger pressure drop, achieving a valve authority of 0.5. The valve is modeled using an instance of Buildings.Fluid.Actuators.Valves.TwoWayEqualPercentage.
On the IT side is a circulation pump that is controlled to track a set point for the head between the two fluid ports. Note that this head is not the pump head, but rather the head between the fluid ports of the CDU, and hence it takes into account the flow resistance of the heat exchanger. The controller for the pump is configured by default as a PI-controller.
Note that the head, specified through the parameter dpPum_nominal,
is the head of the CDU.
To properly size the pump, set dpPum_nominal to the flow resistance that is
external to the CDU, plus the flow resistance of the heat exchanger dpHex_nominal
and the filter.
The pump is modeled using an instance of Buildings.Fluid.Movers.Preconfigured.SpeedControlled_y.
On the IT side, there is also an expansion vessel, modeled using an instance of Buildings.Fluid.Storage.ExpansionVessel. This component sets a reference static pressure, and if the medium model computes density as a function of temperature during the simulation, it provides a volume for the medium's thermal expansion. Note however that to improve computing performance, the medium Buildings.Media.Antifreeze.PropyleneGlycolWater assumes density as constant during the simulation.
Extends from Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialFourPortInterface (Partial model with four ports and declaration of quantities that are used by CDU models).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumPla | PartialMedium | Medium in the plant-side component | |
| replaceable package MediumRac | PartialMedium | Medium in the rack-side component | |
| Generic_epsNTU | dat | Data record for performance characterization | |
| Boolean | addPowerToMedium | true | Set to false to avoid any power from the pump (=heat and flow work) being added to medium (may give simpler equations) |
| PartialFourPortInterface | hex | redeclare Buildings.Fluid.In... | Heat exchanger |
| flowParameters | pumpHeadMonotone | pumpHeadMonotone(V_flow=dat.... | Actual head of the pump, corrected to impose a minimum descent of the pump curve |
| Nominal condition | |||
| MassFlowRate | mPla_flow_nominal | dat.mPla_flow_nominal | Nominal mass flow rate [kg/s] |
| MassFlowRate | mRac_flow_nominal | dat.mRac_flow_nominal | Nominal mass flow rate [kg/s] |
| Valve controller | |||
| SimpleController | controllerTypeVal | Buildings.Controls.OBC.CDL.T... | Type of controller for valve |
| Real | kVal | 1 | Gain of controller for valve |
| Real | TiVal | 120 | Time constant of integrator block of valve controller |
| Real | TdVal | 0.1 | Time constant of derivative block for valve controller |
| Pump controller | |||
| SimpleController | controllerTypePum | Buildings.Controls.OBC.CDL.T... | Type of controller for pump |
| Real | kPum | 1 | Gain of controller for pump |
| Real | TiPum | 120 | Time constant of integrator block of pump controller |
| Real | TdPum | 0.1 | Time constant of derivative block for pump controller |
| Assumptions | |||
| Boolean | allowFlowReversalPla | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for plant-side medium |
| Boolean | allowFlowReversalRac | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for rack-side medium |
| Advanced | |||
| MassFlowRate | mPla_flow_small | 1E-4*abs(mPla_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| MassFlowRate | mRac_flow_small | 1E-4*abs(mRac_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 |
| Boolean | checkMedia | true | Set to false to disable media consistency check |
| Flow resistance | |||
| Medium 1 | |||
| Boolean | computeFlowResistancePla | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dpPla | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistancePla | false | = true, use linear relation between m_flow and dp for any flow rate |
| Medium 2 | |||
| Boolean | computeFlowResistanceRac | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dpRac | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistanceRac | false | = true, use linear relation between m_flow and dp for any flow rate |
| Dynamics | |||
| Valve | |||
| Boolean | use_strokeTime | true | Set to true to continuously open and close valve using strokeTime from instance dat |
| Init | initVal | Modelica.Blocks.Types.Init.I... | Type of initialization (no init/steady state/initial state/initial output) |
| Real | yVal_start | 1 | Initial position of actuator |
| Pump | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Time | tau | 1 | Time constant of fluid volume for nominal flow, used if energy or mass balance is dynamic [s] |
| Boolean | use_riseTime | true | Set to true to continuously change motor speed using risetime from instance dat |
| Real | yPum_start | 0 | Initial value of speed |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPort_a | port_aPla | Fluid connector aPla (positive design flow direction is from port_aPla to port_bPla) |
| FluidPort_b | port_bPla | Fluid connector bPla (positive design flow direction is from port_aPla to port_bPla) |
| FluidPort_a | port_aRac | Fluid connector aRac (positive design flow direction is from port_aRac to port_bRac) |
| FluidPort_b | port_bRac | Fluid connector bRac (positive design flow direction is from port_aRac to port_bRac) |
| input RealInput | TSet | Set point temperature for water leaving to the IT rack [K] |
| input RealInput | dpSet | Set point for static pressure provided by CDU [Pa] |
| output RealOutput | P | Electrical power consumed by pump [W] |
Modelica definition
model PartialCDU "Partial model for a CDU"
extends Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialFourPortInterface(
final mPla_flow_nominal=dat.mPla_flow_nominal,
final mRac_flow_nominal=dat.mRac_flow_nominal);
parameter Buildings.Fluid.DataCenters.CDUs.LiquidToLiquid.Data.Generic_epsNTU
dat
"Data record for performance characterization";
parameter Boolean checkMedia=true
"Set to false to disable media consistency check";
// Flow resistance parameters
parameter Boolean computeFlowResistancePla=true
"=true, compute flow resistance. Set to false to assume no friction";
parameter Boolean from_dpPla=false
"= true, use m_flow = f(dp) else dp = f(m_flow)";
parameter Boolean linearizeFlowResistancePla=false
"= true, use linear relation between m_flow and dp for any flow rate";
parameter Boolean computeFlowResistanceRac=true
"=true, compute flow resistance. Set to false to assume no friction";
parameter Boolean from_dpRac=false
"= true, use m_flow = f(dp) else dp = f(m_flow)";
parameter Boolean linearizeFlowResistanceRac=false
"= true, use linear relation between m_flow and dp for any flow rate";
// Valve
parameter Boolean use_strokeTime=true
"Set to true to continuously open and close valve using strokeTime from instance dat";
parameter Modelica.Blocks.Types.Init initVal=Modelica.Blocks.Types.Init.InitialOutput
"Type of initialization (no init/steady state/initial state/initial output)";
parameter Real yVal_start=1 "Initial position of actuator";
// Pump
parameter Modelica.Fluid.Types.Dynamics energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial
"Type of energy balance: dynamic (3 initialization options) or steady state";
parameter Modelica.Units.SI.Time tau=1
"Time constant of fluid volume for nominal flow, used if energy or mass balance is dynamic";
parameter Boolean use_riseTime=true
"Set to true to continuously change motor speed using risetime from instance dat";
parameter Real yPum_start=0 "Initial value of speed";
parameter Boolean addPowerToMedium=true
"Set to false to avoid any power from the pump (=heat and flow work) being added to medium (may give simpler equations)";
// Valve controller parameters
parameter Controls.OBC.CDL.Types.SimpleController controllerTypeVal=Buildings.Controls.OBC.CDL.Types.SimpleController.PI
"Type of controller for valve";
parameter Real kVal=1 "Gain of controller for valve";
parameter Real TiVal=120
"Time constant of integrator block of valve controller";
parameter Real TdVal=0.1
"Time constant of derivative block for valve controller";
// Pump controller parameters
parameter Controls.OBC.CDL.Types.SimpleController controllerTypePum=Buildings.Controls.OBC.CDL.Types.SimpleController.PI
"Type of controller for pump";
parameter Real kPum=1 "Gain of controller for pump";
parameter Real TiPum=120
"Time constant of integrator block of pump controller";
parameter Real TdPum=0.1
"Time constant of derivative block for pump controller";
// Connectors
Buildings.Controls.OBC.CDL.Interfaces.RealInput TSet(
final unit="K",
displayUnit="degC")
"Set point temperature for water leaving to the IT rack";
Buildings.Controls.OBC.CDL.Interfaces.RealInput dpSet(min=0, final unit="Pa")
"Set point for static pressure provided by CDU";
Modelica.Blocks.Interfaces.RealOutput P(
final unit="W")
"Electrical power consumed by pump";
// Components
Controls.OBC.CDL.Reals.PID conVal(
u_s(final unit="K", displayUnit="degC"),
u_m(final unit="K", displayUnit="degC"),
final controllerType=controllerTypeVal,
final k=kVal,
final Ti=TiVal,
final Td=TdVal,
final reverseActing=false,
r=10,
xi_start=1)
"Controller for valve";
Controls.OBC.CDL.Reals.PID conPum(
u_s(final unit="Pa"),
u_m(final unit="Pa"),
final controllerType=controllerTypePum,
final k=kPum,
final Ti=TiPum,
final Td=TdPum,
final reverseActing=true,
r=dat.dpPumpExt_nominal,
xi_start=1)
"Controller for pump";
replaceable Buildings.Fluid.Interfaces.PartialFourPortInterface hex
constrainedby Buildings.Fluid.Interfaces.PartialFourPortInterface(
redeclare final package Medium1 = MediumPla,
redeclare final package Medium2 = MediumRac,
final allowFlowReversal1=allowFlowReversalPla,
final allowFlowReversal2=allowFlowReversalRac,
final m1_flow_nominal=mPla_flow_nominal,
final m2_flow_nominal=mRac_flow_nominal,
final show_T=show_T) "Heat exchanger";
Fluid.Actuators.Valves.TwoWayEqualPercentage val(
redeclare final package Medium = MediumPla,
final allowFlowReversal=allowFlowReversalPla,
m_flow_nominal=dat.mPla_flow_nominal,
final from_dp=from_dpPla,
final linearized=linearizeFlowResistancePla,
final CvData=Buildings.Fluid.Types.CvTypes.OpPoint,
dpValve_nominal=dat.dpValve_nominal,
final use_strokeTime=use_strokeTime,
final strokeTime=dat.strokeTime,
final init=initVal,
final y_start=yVal_start) "Control valve on chilled water side";
// Use sqrt for efficiency because input is the total efficiency, but this is split up into a
// motor and a hyraulic efficiency which are then multiplied with each other.
Fluid.Movers.SpeedControlled_y pum(
redeclare final package Medium = MediumRac,
energyDynamics=energyDynamics,
final allowFlowReversal=allowFlowReversalRac,
addPowerToMedium=addPowerToMedium,
final tau=tau,
final use_riseTime=use_riseTime,
final riseTime=dat.riseTime,
final y_start=yPum_start,
per(
pressure=pumpHeadMonotone,
powerOrEfficiencyIsHydraulic=true,
etaHydMet=Buildings.Fluid.Movers.BaseClasses.Types.HydraulicEfficiencyMethod.Efficiency_VolumeFlowRate,
etaMotMet=Buildings.Fluid.Movers.BaseClasses.Types.MotorEfficiencyMethod.Efficiency_VolumeFlowRate,
efficiency(
V_flow=dat.pumpEfficiency.V_flow,
eta={sqrt(dat.pumpEfficiency.eta[i]) for i in 1:size(dat.pumpEfficiency.eta, 1)}),
motorEfficiency(
V_flow=dat.pumpEfficiency.V_flow,
eta={sqrt(dat.pumpEfficiency.eta[i]) for i in 1:size(dat.pumpEfficiency.eta, 1)})),
final inputType=Buildings.Fluid.Types.InputType.Continuous,
final init=Modelica.Blocks.Types.Init.InitialOutput)
"Pump on IT side";
Fluid.FixedResistances.PressureDrop fil(
redeclare final package Medium = MediumRac,
final allowFlowReversal=allowFlowReversalRac,
final m_flow_nominal=mRac_flow_nominal,
final dp_nominal=dat.dpFilRac_nominal,
final n=dat.nFilRac)
"Filter";
Fluid.Storage.ExpansionVessel exp(
redeclare package Medium = MediumRac,
final V_start=dat.VExp) "Expansion vessel";
Fluid.Sensors.RelativePressure senRelPre(
redeclare package Medium = MediumRac)
"Differential pressure sensor";
Fluid.Sensors.TemperatureTwoPort senTemRacSup(
redeclare final package Medium = MediumRac,
final allowFlowReversal=allowFlowReversalRac,
final m_flow_nominal=mRac_flow_nominal)
"Temperature sensor for medium leaving towards IT racks";
parameter Buildings.Fluid.Movers.BaseClasses.Characteristics.flowParameters pumpHeadMonotone(
V_flow=dat.pumpHead.V_flow,
dp=if pumpDP_isMonotonicDecreasing then dat.pumpHead.dp
else
cat(1,
{max(dat.pumpHead.dp[i], (1 + (nPumpDat-i)/nPumpDat/100) * max(dat.pumpHead.dp[i+1:nPumpDat])) for i in 1:nPumpDat-1},
{dat.pumpHead.dp[nPumpDat]}))
"Actual head of the pump, corrected to impose a minimum descent of the pump curve";
protected
final parameter Integer nPumpDat = size(dat.pumpHead.dp, 1)
"Number of support point for pump data";
final parameter Boolean pumpDP_isMonotonicDecreasing = (dat.pumpHead.dp[1] > dat.pumpHead.dp[end]) and
Buildings.Utilities.Math.Functions.isMonotonic(
x=dat.pumpHead.dp,
strict=false)
"Flag, true if the pump pressure drop is monotonic";
initial equation
if checkMedia then
// Assert that the media are consistent with the medium types declared in the parameter record
assert(
(dat.medPla == Buildings.Fluid.DataCenters.CDUs.Types.Media.Water and
Modelica.Utilities.Strings.find(MediumPla.mediumName, "Water") > 0) or
(dat.medPla == Buildings.Fluid.DataCenters.CDUs.Types.Media.EthyleneGlycol and
Modelica.Utilities.Strings.find(MediumPla.mediumName, "EthyleneGlycol") > 0) or
(dat.medPla == Buildings.Fluid.DataCenters.CDUs.Types.Media.PropyleneGlycol and
Modelica.Utilities.Strings.find(MediumPla.mediumName, "PropyleneGlycol") > 0),
"In " + getInstanceName() + ": The plant-side medium '" + MediumPla.mediumName
+ "' does not match the medium type dat.medPla = "
+ String(dat.medPla) + " declared in the parameter record."
+ "\nSet the parameter checkMedia=false to avoid this check.");
assert(
(dat.medRac == Buildings.Fluid.DataCenters.CDUs.Types.Media.Water and
Modelica.Utilities.Strings.find(MediumRac.mediumName, "Water") > 0) or
(dat.medRac == Buildings.Fluid.DataCenters.CDUs.Types.Media.EthyleneGlycol and
Modelica.Utilities.Strings.find(MediumRac.mediumName, "EthyleneGlycol") > 0) or
(dat.medRac == Buildings.Fluid.DataCenters.CDUs.Types.Media.PropyleneGlycol and
Modelica.Utilities.Strings.find(MediumRac.mediumName, "PropyleneGlycol") > 0),
"In " + getInstanceName() + ": The rack-side medium '" + MediumRac.mediumName
+ "' does not match the medium type dat.medRac = "
+ String(dat.medRac) + " declared in the parameter record."
+ "\nSet the parameter checkMedia=false to avoid this check.");
end if;
assert(pumpDP_isMonotonicDecreasing,
"In " + getInstanceName() + ": Parameter dat.pumpHead is not monotonic decreasing.
This is usually if dat.dpHexRac_nominal + dat.dpFilRac_nominal are too large compared to the decrease in dat.pumpExtHead.
The model will use pumpHeadMonotone instead of dat.pumpHead. Please check your data to avoid this warning.
Model has the following parameters:
dat.dpHexRac_nominal + dpFilRac_nominal = " + String(dat.dpHexRac_nominal) + " + " + String(dat.dpFilRac_nominal) + " = " + String(dat.dpHexRac_nominal + dat.dpFilRac_nominal) + " Pa
dat.pumpExtHead.dp[1] - dat.pumpExtHead.dp[end] = " + String(dat.pumpExtHead.dp[1] - dat.pumpExtHead.dp[end]) + " Pa.",
level=AssertionLevel.warning);
equation
connect(port_aPla, val.port_a);
connect(val.port_b, hex.port_a1);
connect(hex.port_b1, port_bPla);
connect(pum.port_a, hex.port_b2);
connect(pum.P, P);
connect(pum.port_a, exp.port_a);
connect(senRelPre.port_b, port_aRac);
connect(senRelPre.port_a, port_bRac);
connect(dpSet, conPum.u_s);
connect(senRelPre.p_rel, conPum.u_m);
connect(TSet, conVal.u_s);
connect(senTemRacSup.T, conVal.u_m);
connect(conVal.y, val.y);
connect(conPum.y, pum.y);
connect(senTemRacSup.port_b, port_bRac);
connect(senTemRacSup.port_a, fil.port_b);
connect(fil.port_a, pum.port_b);
connect(hex.port_a2, port_aRac);
end PartialCDU;
Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialFourPort
Partial model with four ports
Information
This model defines an interface for components with four ports.
The parameters allowFlowReversalPla and
allowFlowReversalRac may be used by models that extend
this model to treat flow reversal.
This model is identical to Buildings.Fluid.Interfaces.PartialFourPort, except that instances have been renamed for use with CDUs.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumPla | Modelica.Media.Interfaces.Pa... | Medium in the plant-side component | |
| replaceable package MediumRac | Modelica.Media.Interfaces.Pa... | Medium in the rack-side component | |
| Assumptions | |||
| Boolean | allowFlowReversalPla | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for plant-side medium |
| Boolean | allowFlowReversalRac | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for rack-side medium |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package MediumPla | Medium in the plant-side component | |
| replaceable package MediumRac | Medium in the rack-side component | |
| FluidPort_a | port_aPla | Fluid connector aPla (positive design flow direction is from port_aPla to port_bPla) |
| FluidPort_b | port_bPla | Fluid connector bPla (positive design flow direction is from port_aPla to port_bPla) |
| FluidPort_a | port_aRac | Fluid connector aRac (positive design flow direction is from port_aRac to port_bRac) |
| FluidPort_b | port_bRac | Fluid connector bRac (positive design flow direction is from port_aRac to port_bRac) |
Modelica definition
partial model PartialFourPort "Partial model with four ports"
replaceable package MediumPla =
Modelica.Media.Interfaces.PartialMedium "Medium in the plant-side component";
replaceable package MediumRac =
Modelica.Media.Interfaces.PartialMedium "Medium in the rack-side component";
parameter Boolean allowFlowReversalPla = true
"= false to simplify equations, assuming, but not enforcing, no flow reversal for plant-side medium";
parameter Boolean allowFlowReversalRac = true
"= false to simplify equations, assuming, but not enforcing, no flow reversal for rack-side medium";
Modelica.Fluid.Interfaces.FluidPort_a port_aPla(
redeclare final package Medium = MediumPla,
m_flow(min=if allowFlowReversalPla then -Modelica.Constants.inf else 0),
h_outflow(start = MediumPla.h_default, nominal = MediumPla.h_default))
"Fluid connector aPla (positive design flow direction is from port_aPla to port_bPla)";
Modelica.Fluid.Interfaces.FluidPort_b port_bPla(
redeclare final package Medium = MediumPla,
m_flow(max=if allowFlowReversalPla then +Modelica.Constants.inf else 0),
h_outflow(start = MediumPla.h_default, nominal = MediumPla.h_default))
"Fluid connector bPla (positive design flow direction is from port_aPla to port_bPla)";
Modelica.Fluid.Interfaces.FluidPort_a port_aRac(
redeclare final package Medium = MediumRac,
m_flow(min=if allowFlowReversalRac then -Modelica.Constants.inf else 0),
h_outflow(start = MediumRac.h_default, nominal = MediumRac.h_default))
"Fluid connector aRac (positive design flow direction is from port_aRac to port_bRac)";
Modelica.Fluid.Interfaces.FluidPort_b port_bRac(
redeclare final package Medium = MediumRac,
m_flow(max=if allowFlowReversalRac then +Modelica.Constants.inf else 0),
h_outflow(start = MediumRac.h_default, nominal = MediumRac.h_default))
"Fluid connector bRac (positive design flow direction is from port_aRac to port_bRac)";
end PartialFourPort;
Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialFourPortInterface
Partial model with four ports and declaration of quantities that are used by CDU models
Information
This component defines the interface for models with four fluid ports and two fluid streams. It is similar to Buildings.Fluid.Interfaces.PartialFourPortInterface, but it has four ports instead of two, and the ports are renamed for CDUs.
Extends from Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialFourPort (Partial model with four ports).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumPla | PartialMedium | Medium in the plant-side component | |
| replaceable package MediumRac | PartialMedium | Medium in the rack-side component | |
| Nominal condition | |||
| MassFlowRate | mPla_flow_nominal | Nominal mass flow rate [kg/s] | |
| MassFlowRate | mRac_flow_nominal | Nominal mass flow rate [kg/s] | |
| Assumptions | |||
| Boolean | allowFlowReversalPla | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for plant-side medium |
| Boolean | allowFlowReversalRac | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for rack-side medium |
| Advanced | |||
| MassFlowRate | mPla_flow_small | 1E-4*abs(mPla_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| MassFlowRate | mRac_flow_small | 1E-4*abs(mRac_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 |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPort_a | port_aPla | Fluid connector aPla (positive design flow direction is from port_aPla to port_bPla) |
| FluidPort_b | port_bPla | Fluid connector bPla (positive design flow direction is from port_aPla to port_bPla) |
| FluidPort_a | port_aRac | Fluid connector aRac (positive design flow direction is from port_aRac to port_bRac) |
| FluidPort_b | port_bRac | Fluid connector bRac (positive design flow direction is from port_aRac to port_bRac) |
Modelica definition
partial model PartialFourPortInterface
"Partial model with four ports and declaration of quantities that are used by CDU models"
extends Buildings.Fluid.DataCenters.CDUs.BaseClasses.PartialFourPort;
parameter Modelica.Units.SI.MassFlowRate mPla_flow_nominal(min=0)
"Nominal mass flow rate";
parameter Modelica.Units.SI.MassFlowRate mRac_flow_nominal(min=0)
"Nominal mass flow rate";
parameter MediumPla.MassFlowRate mPla_flow_small(min=0) = 1E-4*abs(mPla_flow_nominal)
"Small mass flow rate for regularization of zero flow";
parameter MediumRac.MassFlowRate mRac_flow_small(min=0) = 1E-4*abs(mRac_flow_nominal)
"Small mass flow rate for regularization of zero flow";
// Diagnostics
parameter Boolean show_T = false
"= true, if actual temperature at port is computed";
MediumPla.MassFlowRate mPla_flow = port_aPla.m_flow
"Mass flow rate from port_aPla to port_bPla (mPla_flow > 0 is design flow direction)";
Modelica.Units.SI.PressureDifference dpPla(displayUnit="Pa") = port_aPla.p - port_bPla.p
"Pressure difference between port_aPla and port_bPla";
MediumRac.MassFlowRate mRac_flow = port_aRac.m_flow
"Mass flow rate from port_aRac to port_bRac (mRac_flow > 0 is design flow direction)";
Modelica.Units.SI.PressureDifference dpRac(displayUnit="Pa") = port_aRac.p - port_bRac.p
"Pressure difference between port_aRac and port_bRac";
MediumPla.ThermodynamicState sta_aPla=
if allowFlowReversalPla then
MediumPla.setState_phX(port_aPla.p,
noEvent(actualStream(port_aPla.h_outflow)),
noEvent(actualStream(port_aPla.Xi_outflow)))
else
MediumPla.setState_phX(port_aPla.p,
inStream(port_aPla.h_outflow),
inStream(port_aPla.Xi_outflow))
if show_T "Medium properties in port_aPla";
MediumPla.ThermodynamicState sta_bPla=
if allowFlowReversalPla then
MediumPla.setState_phX(port_bPla.p,
noEvent(actualStream(port_bPla.h_outflow)),
noEvent(actualStream(port_bPla.Xi_outflow)))
else
MediumPla.setState_phX(port_bPla.p,
port_bPla.h_outflow,
port_bPla.Xi_outflow)
if show_T "Medium properties in port_bPla";
MediumRac.ThermodynamicState sta_aRac=
if allowFlowReversalRac then
MediumRac.setState_phX(port_aRac.p,
noEvent(actualStream(port_aRac.h_outflow)),
noEvent(actualStream(port_aRac.Xi_outflow)))
else
MediumRac.setState_phX(port_aRac.p,
inStream(port_aRac.h_outflow),
inStream(port_aRac.Xi_outflow))
if show_T "Medium properties in port_aRac";
MediumRac.ThermodynamicState sta_bRac=
if allowFlowReversalRac then
MediumRac.setState_phX(port_bRac.p,
noEvent(actualStream(port_bRac.h_outflow)),
noEvent(actualStream(port_bRac.Xi_outflow)))
else
MediumRac.setState_phX(port_bRac.p,
port_bRac.h_outflow,
port_bRac.Xi_outflow)
if show_T "Medium properties in port_bRac";
protected
MediumPla.ThermodynamicState state_aPla_inflow=
MediumPla.setState_phX(port_aPla.p, inStream(port_aPla.h_outflow), inStream(port_aPla.Xi_outflow))
"state for medium inflowing through port_aPla";
MediumPla.ThermodynamicState state_bPla_inflow=
MediumPla.setState_phX(port_bPla.p, inStream(port_bPla.h_outflow), inStream(port_bPla.Xi_outflow))
"state for medium inflowing through port_bPla";
MediumRac.ThermodynamicState state_aRac_inflow=
MediumRac.setState_phX(port_aRac.p, inStream(port_aRac.h_outflow), inStream(port_aRac.Xi_outflow))
"state for medium inflowing through port_aRac";
MediumRac.ThermodynamicState state_bRac_inflow=
MediumRac.setState_phX(port_bRac.p, inStream(port_bRac.h_outflow), inStream(port_bRac.Xi_outflow))
"state for medium inflowing through port_bRac";
end PartialFourPortInterface;