Buildings.DHC.ETS.BaseClasses
Package with base classes
Information
This package contains base classes that are used to construct the classes in Buildings.DHC.ETS.
Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).
Package Content
| Name | Description |
|---|---|
 CollectorDistributor
|
Model of a collector/distributor with zero pressure drop between connections |
 Connection2PipeLossless
|
Model of a lossless connection to a collector/distributor |
 Junction
|
Fluid junction with zero pressure drop |
 PartialDirect
|
Partial direct ETS model for district energy systems with in-building pumping and deltaT control |
 PartialETS
|
Partial class for modeling an energy transfer station |
| PartialIndirect
|
Partial indirect energy transfer station for district energy systems |
 Pump_m_flow
|
Pump with prescribed mass flow rate |
 StratifiedTank
|
Stratified buffer tank model |
 computeCoordinates
|
Coordinates of evenly distributed boreholes given the number of boreholes |
 Validation
|
Collection of validation models |
Buildings.DHC.ETS.BaseClasses.CollectorDistributor
Model of a collector/distributor with zero pressure drop between connections
Information
This model represents a collector/distributor which connects
nCon hydronic circuits in parallel.
The pressure drop between each connection is assumed negligible
compared to the pressure drop in each circuit, and is set to zero
in the model.
By default,
-
there is no bypass flow (which can be added later by connecting
the ports
port_bDisSupandport_aDisRet), -
the nominal distribution mass flow rate
mDis_flow_nominalis equal to the sum of the nominal mass flow rate in each circuit. However, this parameter assigment is not final and it can be set for instance to a higher value to represent a primary overflow in a supply through loop.
Extends from Buildings.DHC.Networks.BaseClasses.PartialDistribution2Pipe (Partial model for two-pipe distribution network).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nCon | Number of connections | |
| replaceable package Medium | PartialMedium | Medium model | |
| replaceable model Model_pipDis | Fluid.FixedResistances.Lossl... | Model for distribution pipe | |
| Integer | iConDpSen | -1 | Index of the connection where the pressure drop is measured |
| Boolean | show_entFlo | false | Set to true to output enthalpy flow rate difference at each connection |
| Nominal condition | |||
| MassFlowRate | mDis_flow_nominal | sum(mCon_flow_nominal) | Nominal mass flow rate in the distribution line before the first connection [kg/s] |
| MassFlowRate | mCon_flow_nominal[nCon] | Nominal mass flow rate in each connection line [kg/s] | |
| MassFlowRate | mEnd_flow_nominal | mDis_flow_nominal | Nominal mass flow rate in the end of the distribution line [kg/s] |
| MassFlowRate | mDisCon_flow_nominal[nCon] | fill(mDis_flow_nominal, nCon) | Nominal mass flow rate in the distribution line before each connection [kg/s] |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = true to allow flow reversal, false restricts to design direction (port_a -> port_b) |
| Dynamics | |||
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Nominal condition | |||
| Time | tau | 10 | Time constant at nominal flow for dynamic energy and momentum balance [s] |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPorts_a | ports_aCon[nCon] | Connection return ports |
| FluidPorts_b | ports_bCon[nCon] | Connection supply ports |
| FluidPort_a | port_aDisSup | Distribution supply inlet port |
| FluidPort_b | port_bDisSup | Distribution supply outlet port |
| replaceable model Model_pipDis | Model for distribution pipe | |
| FluidPort_b | port_bDisRet | Distribution return outlet port |
| FluidPort_a | port_aDisRet | Distribution return inlet port |
| output RealOutput | dp | Pressure difference at given location (measured) [Pa] |
| output RealOutput | dH_flow[nCon] | Difference in enthalpy flow rate between connection supply and return [W] |
| output RealOutput | mCon_flow[nCon] | Connection supply mass flow rate (measured) [kg/s] |
Modelica definition
model CollectorDistributor
"Model of a collector/distributor with zero pressure drop between connections"
extends Buildings.DHC.Networks.BaseClasses.PartialDistribution2Pipe(
mDis_flow_nominal=sum(
mCon_flow_nominal),
final mDisCon_flow_nominal=fill(
mDis_flow_nominal,
nCon),
final mEnd_flow_nominal=mDis_flow_nominal,
final allowFlowReversal=true,
final iConDpSen=-1,
redeclare Connection2PipeLossless con[nCon],
redeclare model Model_pipDis=Fluid.FixedResistances.LosslessPipe);
end CollectorDistributor;
Buildings.DHC.ETS.BaseClasses.Connection2PipeLossless
Model of a lossless connection to a collector/distributor
Information
This is a model of a connection for a two-pipe system using a pipe model with no flow resistance, no heat loss and no transport delay.
Extends from Buildings.DHC.Networks.BaseClasses.PartialConnection2Pipe (Partial model for connecting an agent to a two-pipe distribution network).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable model Model_pipDisSup | PartialTwoPortInterface | Interface for inlet pipe for the distribution supply | |
| replaceable model Model_pipDisRet | PartialTwoPortInterface | Interface for outlet pipe for the distribution return | |
| replaceable package Medium | PartialMedium | Medium model | |
| replaceable model Model_pipCon | Buildings.Fluid.FixedResista... | ||
| Boolean | show_entFlo | false | Set to true to output enthalpy flow rate difference |
| Nominal condition | |||
| MassFlowRate | mDis_flow_nominal | Nominal mass flow rate in the distribution line [kg/s] | |
| MassFlowRate | mCon_flow_nominal | Nominal mass flow rate in the connection line [kg/s] | |
| Assumptions | |||
| Boolean | allowFlowReversal | false | = true to allow flow reversal, false restricts to design direction (port_a -> port_b) |
| Dynamics | |||
| Equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Nominal condition | |||
| Time | tau | 10 | Time constant at nominal flow for dynamic energy and momentum balance [s] |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable model Model_pipDisSup | Interface for inlet pipe for the distribution supply | |
| replaceable model Model_pipDisRet | Interface for outlet pipe for the distribution return | |
| FluidPort_a | port_aDisSup | Distribution supply inlet port |
| FluidPort_b | port_bDisSup | Distribution supply outlet port |
| FluidPort_a | port_aDisRet | Distribution return inlet port |
| FluidPort_b | port_bDisRet | Distribution return outlet port |
| FluidPort_b | port_bCon | Connection supply port |
| FluidPort_a | port_aCon | Connection return port |
| replaceable model Model_pipCon | ||
| output RealOutput | mCon_flow | Connection supply mass flow rate [kg/s] |
| output RealOutput | dp | Pressure drop accross the connection (measured) [Pa] |
| output RealOutput | dH_flow | Difference in enthalpy flow rate between connection supply and return [W] |
Modelica definition
model Connection2PipeLossless
"Model of a lossless connection to a collector/distributor"
extends Buildings.DHC.Networks.BaseClasses.PartialConnection2Pipe(
redeclare model Model_pipDisSup =
Buildings.Fluid.FixedResistances.LosslessPipe,
redeclare model Model_pipDisRet =
Buildings.Fluid.FixedResistances.LosslessPipe,
redeclare model Model_pipCon=Buildings.Fluid.FixedResistances.LosslessPipe);
end Connection2PipeLossless;
Buildings.DHC.ETS.BaseClasses.Junction
Fluid junction with zero pressure drop
Information
This is a model of a fluid junction with zero pressure drop. By default the model is configured in steady-state.
Extends from Fluid.FixedResistances.Junction (Flow splitter with fixed resistance at each port).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Nominal condition | |||
| MassFlowRate | m_flow_nominal[3] | Mass flow rate. Set negative at outflowing ports. [kg/s] | |
| Pressure | dp_nominal[3] | fill(0, 3) | Pressure drop at nominal mass flow rate, set to zero or negative number at outflowing ports. [Pa] |
| Transition to laminar | |||
| Real | deltaM | 0.3 | Fraction of nominal mass flow rate where transition to turbulent occurs |
| Dynamics | |||
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| MassFlowRate | mDyn_flow_nominal | sum(abs(m_flow_nominal[:])/3) | Nominal mass flow rate for dynamic momentum and energy balance [kg/s] |
| Nominal condition | |||
| Time | tau | 10 | Time constant at nominal flow for dynamic energy and momentum balance [s] |
| 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.) |
| Advanced | |||
| Boolean | from_dp | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| PortFlowDirection | portFlowDirection_1 | Modelica.Fluid.Types.PortFlo... | Flow direction for port_1 |
| PortFlowDirection | portFlowDirection_2 | Modelica.Fluid.Types.PortFlo... | Flow direction for port_2 |
| PortFlowDirection | portFlowDirection_3 | Modelica.Fluid.Types.PortFlo... | Flow direction for port_3 |
| Boolean | verifyFlowReversal | false | =true, to assert that the flow does not reverse when portFlowDirection_* does not equal Bidirectional |
| MassFlowRate | m_flow_small | mDyn_flow_nominal*1e-4 | Small mass flow rate for checking flow reversal [kg/s] |
| Boolean | linearized | false | = true, use linear relation between m_flow and dp for any flow rate |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPort_a | port_1 | First port, typically inlet |
| FluidPort_b | port_2 | Second port, typically outlet |
| FluidPort_a | port_3 | Third port, can be either inlet or outlet |
Modelica definition
model Junction
"Fluid junction with zero pressure drop"
extends Fluid.FixedResistances.Junction(
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
final dp_nominal=fill(
0,
3),
final from_dp=false);
end Junction;
Buildings.DHC.ETS.BaseClasses.PartialDirect
Partial direct ETS model for district energy systems with in-building pumping and deltaT control
Information
Direct cooling energy transfer station (ETS) model with in-building pumping and deltaT control. The design is based on a typical district cooling ETS described in ASHRAE's District Cooling Guide. As shown in the figure below, the district and building piping are hydronically coupled. The control valve ensures that the return temperature to the district cooling network is at or above the minimum specified value. This configuration naturally results in a fluctuating building supply tempearture.
Reference
American Society of Heating, Refrigeration and Air-Conditioning Engineers. (2019). Chapter 5: End User Interface. In District Cooling Guide, Second Edition and Owner's Guide for Buildings Served by District Cooling.
Extends from Buildings.DHC.ETS.BaseClasses.PartialETS (Partial class for modeling an energy transfer station).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumSer | Water | Service side medium | |
| replaceable package MediumSerHea_a | Water | Service side medium at heating inlet | |
| replaceable package MediumBui | Water | Building side medium | |
| Generic | fue[nFue] | Fuel type | |
| Configuration | |||
| DistrictSystemType | typ | Buildings.DHC.Types.District... | Type of district system |
| Boolean | have_heaWat | false | Set to true if the ETS supplies heating water |
| Boolean | have_hotWat | false | Set to true if the ETS supplies hot water |
| Boolean | have_chiWat | false | Set to true if the ETS supplies chilled water |
| Boolean | have_fan | false | Set to true if fan power is computed |
| Boolean | have_pum | false | Set to true if pump power is computed |
| Boolean | have_eleHea | false | Set to true if the ETS has electric heating system |
| Integer | nFue | 0 | Number of fuel types (0 means no combustion system) |
| Boolean | have_eleCoo | false | Set to true if the ETS has electric cooling system |
| Boolean | have_weaBus | false | Set to true to use a weather bus |
| Nominal condition | |||
| HeatFlowRate | QHeaWat_flow_nominal | 0 | Nominal capacity of heating system (>=0) [W] |
| HeatFlowRate | QHotWat_flow_nominal | 0 | Nominal capacity of hot water production system (>=0) [W] |
| HeatFlowRate | QChiWat_flow_nominal | 0 | Nominal capacity of cooling system (<=0) [W] |
| MassFlowRate | mBui_flow_nominal | Nominal mass flow rate of building side [kg/s] | |
| PressureDifference | dpConVal_nominal | 50 | Nominal pressure drop in the control valve [Pa] |
| PressureDifference | dpCheVal_nominal | 6000 | Nominal pressure drop in the check valve [Pa] |
| PID controller | |||
| SimpleController | controllerType | Modelica.Blocks.Types.Simple... | Type of controller |
| Real | k | 0.1 | Gain of controller [1] |
| Time | Ti | 60 | Time constant of integrator block [s] |
| Time | Td | 0.1 | Time constant of derivative block [s] |
| Real | yMax | 1 | Upper limit of output |
| Real | yMin | 0 | Lower limit of output |
| Assumptions | |||
| Boolean | allowFlowReversalSer | false | Set to true to allow flow reversal on service side |
| Boolean | allowFlowReversalBui | false | Set to true to allow flow reversal on building side |
| Advanced | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Real | bandwidth | 0.2 | Bandwidth around reference signal for on/off controller |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPorts_a | ports_aHeaWat[nPorts_aHeaWat] | Fluid connectors for heating water return (from building) |
| FluidPorts_b | ports_bHeaWat[nPorts_bHeaWat] | Fluid connectors for heating water supply (to building) |
| FluidPorts_a | ports_aChiWat[nPorts_aChiWat] | Fluid connectors for chilled water return (from building) |
| FluidPorts_b | ports_bChiWat[nPorts_bChiWat] | Fluid connectors for chilled water supply (to building) |
| FluidPort_a | port_aSerAmb | Fluid connector for ambient water service supply line |
| FluidPort_b | port_bSerAmb | Fluid connector for ambient water service return line |
| FluidPort_a | port_aSerHea | Fluid connector for heating service supply line |
| FluidPort_b | port_bSerHea | Fluid connector for heating service return line |
| FluidPort_a | port_aSerCoo | Fluid connector for cooling service supply line |
| FluidPort_b | port_bSerCoo | Fluid connector for cooling service return line |
| output RealOutput | PHea | Power drawn by heating system [W] |
| output RealOutput | PCoo | Power drawn by cooling system [W] |
| output RealOutput | PFan | Power drawn by fan motors [W] |
| output RealOutput | PPum | Power drawn by pump motors [W] |
| output RealOutput | QFue_flow[nFue] | Fuel energy input rate [W] |
| Bus | weaBus | Weather data bus |
| input RealInput | TDisRetSet | Setpoint for the district return temperature (min for cooling, max for heating) [K] |
| output RealOutput | Q_flow | Measured heating demand at the ETS [W] |
| output RealOutput | Q | Measured energy consumption at the ETS [J] |
Modelica definition
model PartialDirect
"Partial direct ETS model for district energy systems with in-building pumping and deltaT control"
extends Buildings.DHC.ETS.BaseClasses.PartialETS(
final have_weaBus=false,
final have_hotWat=false,
final have_eleHea=false,
final nFue=0,
final have_eleCoo=false,
final have_pum=false,
final have_fan=false);
// Mass flow rate
parameter Modelica.Units.SI.MassFlowRate mBui_flow_nominal(
final min=0)
"Nominal mass flow rate of building side";
// Pressure drops
parameter Modelica.Units.SI.PressureDifference dpConVal_nominal(
final min=0,
displayUnit="Pa")=50
"Nominal pressure drop in the control valve";
parameter Modelica.Units.SI.PressureDifference dpCheVal_nominal(
final min=0,
displayUnit="Pa")=6000
"Nominal pressure drop in the check valve";
// Controller parameters
parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PI
"Type of controller";
parameter Real k(
final min=0,
final unit="1")=0.1
"Gain of controller";
parameter Modelica.Units.SI.Time Ti(
final min=Modelica.Constants.small)=60
"Time constant of integrator block";
parameter Modelica.Units.SI.Time Td(
final min=0)=0.1
"Time constant of derivative block";
parameter Real yMax=1
"Upper limit of output";
parameter Real yMin=0
"Lower limit of output";
// Advanced parameters
parameter Modelica.Fluid.Types.Dynamics energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial
"Type of energy balance: dynamic (3 initialization options) or steady state";
parameter Real bandwidth=0.2
"Bandwidth around reference signal for on/off controller";
Modelica.Blocks.Interfaces.RealInput TDisRetSet(
final unit="K",
displayUnit="degC")
"Setpoint for the district return temperature (min for cooling, max for heating)";
Modelica.Blocks.Interfaces.RealOutput Q_flow(
final quantity="HeatFlowRate",
final unit="W",
displayUnit="kW")
"Measured heating demand at the ETS";
Modelica.Blocks.Interfaces.RealOutput Q(
final quantity="Energy",
final unit="J",
displayUnit="kW.h")
"Measured energy consumption at the ETS";
Buildings.Fluid.Sensors.TemperatureTwoPort senTDisSup(
redeclare final package Medium=MediumSer,
final m_flow_nominal=mBui_flow_nominal)
"District supply temperature sensor";
Buildings.Fluid.Sensors.MassFlowRate senMasFlo(
redeclare final package Medium=MediumSer)
"District supply mass flow rate sensor";
Buildings.Fluid.FixedResistances.Junction jun(
redeclare final package Medium=MediumSer,
final energyDynamics=energyDynamics,
final m_flow_nominal=mBui_flow_nominal*{1,-1,1},
final dp_nominal={0,0,0})
"Bypass junction";
Buildings.Fluid.Sensors.TemperatureTwoPort senTDisRet(
redeclare final package Medium=MediumSer,
final m_flow_nominal=mBui_flow_nominal)
"District return temperature sensor";
Buildings.Fluid.FixedResistances.Junction spl(
redeclare final package Medium=MediumSer,
final energyDynamics=energyDynamics,
final m_flow_nominal=mBui_flow_nominal*{1,-1,-1},
final dp_nominal={0,0,0})
"Bypass junction, splitter";
Buildings.Fluid.Actuators.Valves.TwoWayEqualPercentage conVal(
redeclare final package Medium=MediumSer,
final m_flow_nominal=mBui_flow_nominal,
final dpValve_nominal=dpConVal_nominal,
use_inputFilter=true,
riseTime(displayUnit="s") = 60)
"Control valve";
Buildings.Fluid.Sensors.TemperatureTwoPort senTBuiRet(
redeclare final package Medium = MediumSer,
final m_flow_nominal=mBui_flow_nominal)
"Building return temperature sensor";
Fluid.FixedResistances.CheckValve cheVal(
redeclare final package Medium=MediumSer,
final m_flow_nominal=mBui_flow_nominal,
final dpValve_nominal=dpCheVal_nominal)
"Check valve (backflow preventer)";
Modelica.Blocks.Math.Add dTDis(
final k1=-1)
"Temperature difference on the district side";
Modelica.Blocks.Math.Product pro
"Product";
Modelica.Blocks.Math.Gain cp(
final k=cp_default)
"Specific heat multiplier to calculate heat flow rate";
Modelica.Blocks.Continuous.Integrator int(
final k=1)
"Integration";
Controls.OBC.CDL.Reals.PID con(
final controllerType=controllerType,
final k=k,
final Ti=Ti,
final Td=Td,
final yMax=yMax,
final yMin=yMin)
"District return temperature controller";
Buildings.Fluid.Sensors.TemperatureTwoPort senTBuiSup(
redeclare final package Medium = MediumSer,
final m_flow_nominal=mBui_flow_nominal)
"Building supply temperature sensor";
protected
final parameter MediumSer.ThermodynamicState sta_default=MediumSer.setState_pTX(
T=MediumSer.T_default,
p=MediumSer.p_default,
X=MediumSer.X_default)
"Medium state at default properties";
final parameter Modelica.Units.SI.SpecificHeatCapacity cp_default=MediumSer.specificHeatCapacityCp(
sta_default)
"Specific heat capacity of the fluid";
equation
connect(senTDisSup.port_b, senMasFlo.port_a);
connect(senMasFlo.port_b, jun.port_1);
connect(senTBuiRet.port_b, spl.port_1);
connect(spl.port_2, conVal.port_a);
connect(senMasFlo.m_flow, pro.u2);
connect(pro.y, cp.u);
connect(cp.y, Q_flow);
connect(cp.y, int.u);
connect(int.y, Q);
connect(dTDis.y, pro.u1);
connect(conVal.port_b, senTDisRet.port_a);
connect(senTDisRet.T,dTDis. u1);
connect(senTDisSup.T,dTDis. u2);
connect(TDisRetSet, con.u_s);
connect(senTBuiRet.T, con.u_m);
connect(jun.port_2, senTBuiSup.port_a);
connect(spl.port_3, cheVal.port_a);
connect(cheVal.port_b, jun.port_3);
connect(con.y, conVal.y);
end PartialDirect;
Buildings.DHC.ETS.BaseClasses.PartialETS
Partial class for modeling an energy transfer station
Information
Partial class to be used for modeling an energy transfer station and optional in-building primary systems.
The connectors to the service lines are configured based on an enumeration
defining the type of district system (CombinedGeneration2to4
by default), see
Buildings.DHC.Types.DistrictSystemType.
In case of a heating service line, the model allows for using two
different media at the inlet port port_aSerHea and at the oulet
port port_bSerHea to represent a steam supply and condensate
return.
The connectors to the building distribution systems are configured based
on the Boolean parameters have_heaWat and have_chiWat.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumSer | Buildings.Media.Water | Service side medium | |
| replaceable package MediumSerHea_a | Buildings.Media.Water | Service side medium at heating inlet | |
| replaceable package MediumBui | Buildings.Media.Water | Building side medium | |
| Generic | fue[nFue] | Fuel type | |
| Configuration | |||
| DistrictSystemType | typ | Buildings.DHC.Types.District... | Type of district system |
| Boolean | have_heaWat | false | Set to true if the ETS supplies heating water |
| Boolean | have_hotWat | false | Set to true if the ETS supplies hot water |
| Boolean | have_chiWat | false | Set to true if the ETS supplies chilled water |
| Boolean | have_fan | false | Set to true if fan power is computed |
| Boolean | have_pum | false | Set to true if pump power is computed |
| Boolean | have_eleHea | false | Set to true if the ETS has electric heating system |
| Integer | nFue | 0 | Number of fuel types (0 means no combustion system) |
| Boolean | have_eleCoo | false | Set to true if the ETS has electric cooling system |
| Boolean | have_weaBus | false | Set to true to use a weather bus |
| Nominal condition | |||
| HeatFlowRate | QHeaWat_flow_nominal | 0 | Nominal capacity of heating system (>=0) [W] |
| HeatFlowRate | QHotWat_flow_nominal | 0 | Nominal capacity of hot water production system (>=0) [W] |
| HeatFlowRate | QChiWat_flow_nominal | 0 | Nominal capacity of cooling system (<=0) [W] |
| Assumptions | |||
| Boolean | allowFlowReversalSer | false | Set to true to allow flow reversal on service side |
| Boolean | allowFlowReversalBui | false | Set to true to allow flow reversal on building side |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package MediumSer | Service side medium | |
| replaceable package MediumSerHea_a | Service side medium at heating inlet | |
| replaceable package MediumBui | Building side medium | |
| FluidPorts_a | ports_aHeaWat[nPorts_aHeaWat] | Fluid connectors for heating water return (from building) |
| FluidPorts_b | ports_bHeaWat[nPorts_bHeaWat] | Fluid connectors for heating water supply (to building) |
| FluidPorts_a | ports_aChiWat[nPorts_aChiWat] | Fluid connectors for chilled water return (from building) |
| FluidPorts_b | ports_bChiWat[nPorts_bChiWat] | Fluid connectors for chilled water supply (to building) |
| FluidPort_a | port_aSerAmb | Fluid connector for ambient water service supply line |
| FluidPort_b | port_bSerAmb | Fluid connector for ambient water service return line |
| FluidPort_a | port_aSerHea | Fluid connector for heating service supply line |
| FluidPort_b | port_bSerHea | Fluid connector for heating service return line |
| FluidPort_a | port_aSerCoo | Fluid connector for cooling service supply line |
| FluidPort_b | port_bSerCoo | Fluid connector for cooling service return line |
| output RealOutput | PHea | Power drawn by heating system [W] |
| output RealOutput | PCoo | Power drawn by cooling system [W] |
| output RealOutput | PFan | Power drawn by fan motors [W] |
| output RealOutput | PPum | Power drawn by pump motors [W] |
| output RealOutput | QFue_flow[nFue] | Fuel energy input rate [W] |
| Bus | weaBus | Weather data bus |
Modelica definition
partial model PartialETS
"Partial class for modeling an energy transfer station"
import TypDisSys=Buildings.DHC.Types.DistrictSystemType
"District system type enumeration";
replaceable package MediumSer=Buildings.Media.Water
constrainedby Modelica.Media.Interfaces.PartialMedium
"Service side medium";
replaceable package MediumSerHea_a=Buildings.Media.Water
constrainedby Modelica.Media.Interfaces.PartialMedium
"Service side medium at heating inlet";
replaceable package MediumBui=Buildings.Media.Water
constrainedby Modelica.Media.Interfaces.PartialMedium
"Building side medium";
parameter TypDisSys typ = Buildings.DHC.Types.DistrictSystemType.CombinedGeneration2to4
"Type of district system";
parameter Integer nPorts_aHeaWat=0
"Number of heating water return ports";
parameter Integer nPorts_bHeaWat=0
"Number of heating water supply ports";
parameter Integer nPorts_aChiWat=0
"Number of chilled water return ports";
parameter Integer nPorts_bChiWat=0
"Number of chilled water supply ports";
parameter Boolean have_heaWat=false
"Set to true if the ETS supplies heating water";
parameter Boolean have_hotWat=false
"Set to true if the ETS supplies hot water";
parameter Boolean have_chiWat=false
"Set to true if the ETS supplies chilled water";
parameter Boolean have_fan=false
"Set to true if fan power is computed";
parameter Boolean have_pum=false
"Set to true if pump power is computed";
parameter Boolean have_eleHea=false
"Set to true if the ETS has electric heating system";
parameter Integer nFue=0
"Number of fuel types (0 means no combustion system)";
parameter Boolean have_eleCoo=false
"Set to true if the ETS has electric cooling system";
parameter Boolean have_weaBus=false
"Set to true to use a weather bus";
parameter Boolean allowFlowReversalSer=false
"Set to true to allow flow reversal on service side";
parameter Boolean allowFlowReversalBui=false
"Set to true to allow flow reversal on building side";
parameter Modelica.Units.SI.HeatFlowRate QHeaWat_flow_nominal(min=0) = 0
"Nominal capacity of heating system (>=0)";
parameter Modelica.Units.SI.HeatFlowRate QHotWat_flow_nominal(min=0) = 0
"Nominal capacity of hot water production system (>=0)";
parameter Modelica.Units.SI.HeatFlowRate QChiWat_flow_nominal(max=0) = 0
"Nominal capacity of cooling system (<=0)";
parameter Buildings.Fluid.Data.Fuels.Generic fue[nFue]
"Fuel type";
// IO CONNECTORS
Modelica.Fluid.Interfaces.FluidPorts_a ports_aHeaWat[nPorts_aHeaWat](
redeclare each package Medium=MediumBui,
each m_flow(
min=
if allowFlowReversalBui then
-Modelica.Constants.inf
else
0),
each h_outflow(
start=MediumBui.h_default,
nominal=MediumBui.h_default)) if have_heaWat
"Fluid connectors for heating water return (from building)";
Modelica.Fluid.Interfaces.FluidPorts_b ports_bHeaWat[nPorts_bHeaWat](
redeclare each package Medium=MediumBui,
each m_flow(
max=
if allowFlowReversalBui then
+Modelica.Constants.inf
else
0),
each h_outflow(
start=MediumBui.h_default,
nominal=MediumBui.h_default)) if have_heaWat
"Fluid connectors for heating water supply (to building)";
Modelica.Fluid.Interfaces.FluidPorts_a ports_aChiWat[nPorts_aChiWat](
redeclare each package Medium=MediumBui,
each m_flow(
min=
if allowFlowReversalBui then
-Modelica.Constants.inf
else
0),
each h_outflow(
start=MediumBui.h_default,
nominal=MediumBui.h_default)) if have_chiWat
"Fluid connectors for chilled water return (from building)";
Modelica.Fluid.Interfaces.FluidPorts_b ports_bChiWat[nPorts_bChiWat](
redeclare each package Medium=MediumBui,
each m_flow(
max=
if allowFlowReversalBui then
+Modelica.Constants.inf
else
0),
each h_outflow(
start=MediumBui.h_default,
nominal=MediumBui.h_default)) if have_chiWat
"Fluid connectors for chilled water supply (to building)";
Modelica.Fluid.Interfaces.FluidPort_a port_aSerAmb(
redeclare package Medium = MediumSer,
m_flow(min=if allowFlowReversalSer then -Modelica.Constants.inf else 0),
h_outflow(start=MediumSer.h_default, nominal=MediumSer.h_default))
if typ == Buildings.DHC.Types.DistrictSystemType.CombinedGeneration5
"Fluid connector for ambient water service supply line";
Modelica.Fluid.Interfaces.FluidPort_b port_bSerAmb(
redeclare package Medium = MediumSer,
m_flow(max=if allowFlowReversalSer then +Modelica.Constants.inf else 0),
h_outflow(start=MediumSer.h_default, nominal=MediumSer.h_default))
if typ == Buildings.DHC.Types.DistrictSystemType.CombinedGeneration5
"Fluid connector for ambient water service return line";
Modelica.Fluid.Interfaces.FluidPort_a port_aSerHea(
redeclare package Medium = MediumSerHea_a,
m_flow(min=if allowFlowReversalSer then -Modelica.Constants.inf else 0),
h_outflow(start=MediumSerHea_a.h_default, nominal=MediumSerHea_a.h_default))
if typ <> Buildings.DHC.Types.DistrictSystemType.Cooling and
typ <> Buildings.DHC.Types.DistrictSystemType.CombinedGeneration5
"Fluid connector for heating service supply line";
Modelica.Fluid.Interfaces.FluidPort_b port_bSerHea(
redeclare package Medium = MediumSer,
m_flow(max=if allowFlowReversalSer then +Modelica.Constants.inf else 0),
h_outflow(start=MediumSer.h_default, nominal=MediumSer.h_default))
if typ <> Buildings.DHC.Types.DistrictSystemType.Cooling and
typ <> Buildings.DHC.Types.DistrictSystemType.CombinedGeneration5
"Fluid connector for heating service return line";
Modelica.Fluid.Interfaces.FluidPort_a port_aSerCoo(
redeclare package Medium = MediumSer,
m_flow(min=if allowFlowReversalSer then -Modelica.Constants.inf else 0),
h_outflow(start=MediumSer.h_default, nominal=MediumSer.h_default))
if typ == Buildings.DHC.Types.DistrictSystemType.CombinedGeneration1 or
typ == Buildings.DHC.Types.DistrictSystemType.CombinedGeneration2to4 or
typ == Buildings.DHC.Types.DistrictSystemType.Cooling
"Fluid connector for cooling service supply line";
Modelica.Fluid.Interfaces.FluidPort_b port_bSerCoo(
redeclare package Medium = MediumSer,
m_flow(max=if allowFlowReversalSer then +Modelica.Constants.inf else 0),
h_outflow(start=MediumSer.h_default, nominal=MediumSer.h_default))
if typ == Buildings.DHC.Types.DistrictSystemType.CombinedGeneration1 or
typ == Buildings.DHC.Types.DistrictSystemType.CombinedGeneration2to4 or
typ == Buildings.DHC.Types.DistrictSystemType.Cooling
"Fluid connector for cooling service return line";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput PHea(
final unit="W") if have_eleHea
"Power drawn by heating system";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput PCoo(
final unit="W") if have_eleCoo
"Power drawn by cooling system";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput PFan(
final unit="W") if have_fan
"Power drawn by fan motors";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput PPum(
final unit="W") if have_pum
"Power drawn by pump motors";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput QFue_flow[nFue](
each final unit="W") if nFue>0
"Fuel energy input rate";
BoundaryConditions.WeatherData.Bus weaBus if have_weaBus
"Weather data bus";
initial equation
assert(
nPorts_aHeaWat == nPorts_bHeaWat,
"In "+getInstanceName()+": The numbers of heating water supply ports ("+String(
nPorts_bHeaWat)+") and return ports ("+String(
nPorts_aHeaWat)+") must be equal.");
assert(
nPorts_aChiWat == nPorts_bChiWat,
"In "+getInstanceName()+": The numbers of chilled water supply ports ("+String(
nPorts_bChiWat)+") and return ports ("+String(
nPorts_aChiWat)+") must be equal.");
if have_chiWat then
assert(
QChiWat_flow_nominal <-Modelica.Constants.eps,
"In "+getInstanceName()+": Design heat flow rate for chilled water production must be strictly
negative. Obtained QChiWat_flow_nominal = "+String(
QChiWat_flow_nominal));
end if;
if have_heaWat then
assert(
QHeaWat_flow_nominal > Modelica.Constants.eps,
"In "+getInstanceName()+": Design heat flow rate for heating water production must be strictly
positive. Obtained QHeaWat_flow_nominal = "+String(
QHeaWat_flow_nominal));
end if;
if have_hotWat then
assert(
QHotWat_flow_nominal > Modelica.Constants.eps,
"In "+getInstanceName()+": Design heat flow rate for heating water production must be strictly
positive. Obtained QHotWat_flow_nominal = "+String(
QHotWat_flow_nominal));
end if;
end PartialETS;
Buildings.DHC.ETS.BaseClasses.PartialIndirect
Partial indirect energy transfer station for district energy systems
Information
Indirect cooling energy transfer station (ETS) model that controls the building chilled water supply temperature by modulating a primary control valve on the district supply side. The design is based on a typical district cooling ETS described in ASHRAE's District Cooling Guide. As shown in the figure below, the building pumping design (constant/variable) is specified on the building side and not within the ETS.
Reference
American Society of Heating, Refrigeration and Air-Conditioning Engineers. (2019). Chapter 5: End User Interface. In District Cooling Guide, Second Edition and Owner's Guide for Buildings Served by District Cooling.
Extends from Buildings.DHC.ETS.BaseClasses.PartialETS (Partial class for modeling an energy transfer station).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumSer | Water | Service side medium | |
| replaceable package MediumSerHea_a | Water | Service side medium at heating inlet | |
| replaceable package MediumBui | Water | Building side medium | |
| Generic | fue[nFue] | Fuel type | |
| Configuration | |||
| DistrictSystemType | typ | Buildings.DHC.Types.District... | Type of district system |
| Boolean | have_heaWat | false | Set to true if the ETS supplies heating water |
| Boolean | have_hotWat | false | Set to true if the ETS supplies hot water |
| Boolean | have_chiWat | false | Set to true if the ETS supplies chilled water |
| Boolean | have_fan | false | Set to true if fan power is computed |
| Boolean | have_pum | false | Set to true if pump power is computed |
| Boolean | have_eleHea | false | Set to true if the ETS has electric heating system |
| Integer | nFue | 0 | Number of fuel types (0 means no combustion system) |
| Boolean | have_eleCoo | false | Set to true if the ETS has electric cooling system |
| Boolean | have_weaBus | false | Set to true to use a weather bus |
| Nominal condition | |||
| HeatFlowRate | QHeaWat_flow_nominal | 0 | Nominal capacity of heating system (>=0) [W] |
| HeatFlowRate | QHotWat_flow_nominal | 0 | Nominal capacity of hot water production system (>=0) [W] |
| HeatFlowRate | QChiWat_flow_nominal | 0 | Nominal capacity of cooling system (<=0) [W] |
| MassFlowRate | mDis_flow_nominal | Nominal mass flow rate of district side [kg/s] | |
| MassFlowRate | mBui_flow_nominal | Nominal mass flow rate of building side [kg/s] | |
| PressureDifference | dpConVal_nominal | 6000 | Nominal pressure drop of fully open control valve [Pa] |
| Heat exchanger | |||
| PressureDifference | dp1_nominal | Nominal pressure difference on primary side [Pa] | |
| PressureDifference | dp2_nominal | Nominal pressure difference on secondary side [Pa] | |
| Boolean | use_Q_flow_nominal | true | Set to true to specify Q_flow_nominal and temeratures, or to false to specify effectiveness |
| HeatFlowRate | Q_flow_nominal | Nominal heat transfer (positive for heat transfer from district to building) [W] | |
| Temperature | T_a1_nominal | Nominal temperature at port a1 (district supply) [K] | |
| Temperature | T_a2_nominal | Nominal temperature at port a2 (building return) [K] | |
| Efficiency | eta | 0.8 | Constant effectiveness [1] |
| PID controller | |||
| SimpleController | controllerType | Modelica.Blocks.Types.Simple... | Type of controller |
| Real | k | 1 | Gain of controller [1] |
| Time | Ti | 120 | Time constant of integrator block [s] |
| Time | Td | 0.1 | Time constant of derivative block [s] |
| Real | yMax | 1 | Upper limit of output |
| Real | yMin | 0.01 | Lower limit of output |
| Assumptions | |||
| Boolean | allowFlowReversalSer | false | Set to true to allow flow reversal on service side |
| Boolean | allowFlowReversalBui | false | Set to true to allow flow reversal on building side |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPorts_a | ports_aHeaWat[nPorts_aHeaWat] | Fluid connectors for heating water return (from building) |
| FluidPorts_b | ports_bHeaWat[nPorts_bHeaWat] | Fluid connectors for heating water supply (to building) |
| FluidPorts_a | ports_aChiWat[nPorts_aChiWat] | Fluid connectors for chilled water return (from building) |
| FluidPorts_b | ports_bChiWat[nPorts_bChiWat] | Fluid connectors for chilled water supply (to building) |
| FluidPort_a | port_aSerAmb | Fluid connector for ambient water service supply line |
| FluidPort_b | port_bSerAmb | Fluid connector for ambient water service return line |
| FluidPort_a | port_aSerHea | Fluid connector for heating service supply line |
| FluidPort_b | port_bSerHea | Fluid connector for heating service return line |
| FluidPort_a | port_aSerCoo | Fluid connector for cooling service supply line |
| FluidPort_b | port_bSerCoo | Fluid connector for cooling service return line |
| output RealOutput | PHea | Power drawn by heating system [W] |
| output RealOutput | PCoo | Power drawn by cooling system [W] |
| output RealOutput | PFan | Power drawn by fan motors [W] |
| output RealOutput | PPum | Power drawn by pump motors [W] |
| output RealOutput | QFue_flow[nFue] | Fuel energy input rate [W] |
| Bus | weaBus | Weather data bus |
| input RealInput | TBuiSupSet | Setpoint temperature for building supply |
| output RealOutput | Q_flow | Measured heating demand at the ETS [W] |
| output RealOutput | Q | Measured energy consumption at the ETS [J] |
Modelica definition
model PartialIndirect
"Partial indirect energy transfer station for district energy systems"
extends Buildings.DHC.ETS.BaseClasses.PartialETS(
final have_weaBus=false,
final have_hotWat=false,
final have_eleHea=false,
final nFue=0,
final have_eleCoo=false,
final have_pum=false,
final have_fan=false);
// mass flow rates
parameter Modelica.Units.SI.MassFlowRate mDis_flow_nominal(
final min=0)
"Nominal mass flow rate of district side";
parameter Modelica.Units.SI.MassFlowRate mBui_flow_nominal(
final min=0)
"Nominal mass flow rate of building side";
// Primary supply control valve
parameter Modelica.Units.SI.PressureDifference dpConVal_nominal(
final min=0,
displayUnit="Pa")=6000
"Nominal pressure drop of fully open control valve";
// Heat exchanger
parameter Modelica.Units.SI.PressureDifference dp1_nominal(
final min=0,
displayUnit="Pa")
"Nominal pressure difference on primary side";
parameter Modelica.Units.SI.PressureDifference dp2_nominal(
final min=0,
displayUnit="Pa")
"Nominal pressure difference on secondary side";
parameter Boolean use_Q_flow_nominal=true
"Set to true to specify Q_flow_nominal and temeratures, or to false to specify effectiveness";
parameter Modelica.Units.SI.HeatFlowRate Q_flow_nominal
"Nominal heat transfer (positive for heat transfer from district to building)";
parameter Modelica.Units.SI.Temperature T_a1_nominal(
final min=273.15,
final max=373.15)
"Nominal temperature at port a1 (district supply)";
parameter Modelica.Units.SI.Temperature T_a2_nominal(
final min=273.15,
final max=373.15)
"Nominal temperature at port a2 (building return)";
parameter Modelica.Units.SI.Efficiency eta(
final min=0,
final max=1)=0.8
"Constant effectiveness";
//Controller parameters
parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PI
"Type of controller";
parameter Real k(
final min=0,
final unit="1")=1
"Gain of controller";
parameter Modelica.Units.SI.Time Ti(
final min=Modelica.Constants.small)=120
"Time constant of integrator block";
parameter Modelica.Units.SI.Time Td(
final min=0)=0.1
"Time constant of derivative block";
parameter Real yMax=1
"Upper limit of output";
parameter Real yMin=0.01
"Lower limit of output";
Modelica.Blocks.Interfaces.RealInput TBuiSupSet
"Setpoint temperature for building supply";
Modelica.Blocks.Interfaces.RealOutput Q_flow(
final quantity="HeatFlowRate",
final unit="W",
displayUnit="kW")
"Measured heating demand at the ETS";
Modelica.Blocks.Interfaces.RealOutput Q(
final quantity="Energy",
final unit="J",
displayUnit="kW.h")
"Measured energy consumption at the ETS";
Buildings.Fluid.Sensors.TemperatureTwoPort senTDisSup(
redeclare final package Medium=MediumSer,
final m_flow_nominal=mDis_flow_nominal)
"District supply temperature sensor";
Buildings.Fluid.Sensors.MassFlowRate senMasFlo(
redeclare final package Medium=MediumSer)
"District supply mass flow rate sensor";
Buildings.Fluid.Actuators.Valves.TwoWayEqualPercentage conVal(
redeclare final package Medium=MediumSer,
final m_flow_nominal=mDis_flow_nominal,
final dpValve_nominal=dpConVal_nominal,
riseTime(displayUnit="s") = 10,
y_start=0)
"Control valve";
Buildings.Fluid.HeatExchangers.PlateHeatExchangerEffectivenessNTU hex(
redeclare package Medium1 = MediumSer,
redeclare package Medium2 = MediumBui,
final m1_flow_nominal=mDis_flow_nominal,
final m2_flow_nominal=mBui_flow_nominal,
final dp1_nominal=dp1_nominal,
final dp2_nominal=dp2_nominal,
final configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.CounterFlow,
final Q_flow_nominal=Q_flow_nominal,
final T_a1_nominal=T_a1_nominal,
final T_a2_nominal=T_a2_nominal)
"Heat exchanger";
Buildings.Fluid.Sensors.TemperatureTwoPort senTDisRet(
redeclare final package Medium=MediumSer,
final m_flow_nominal=mDis_flow_nominal)
"District return temperature sensor";
Buildings.Fluid.Sensors.TemperatureTwoPort senTBuiRet(
redeclare final package Medium=MediumBui,
final m_flow_nominal=mBui_flow_nominal)
"Building return temperature sensor";
Buildings.Fluid.Sensors.TemperatureTwoPort senTBuiSup(
redeclare final package Medium=MediumBui,
final m_flow_nominal=mBui_flow_nominal)
"Building supply temperature sensor";
Controls.OBC.CDL.Reals.PID con(
final controllerType=controllerType,
final k=k,
final Ti=Ti,
final Td=Td,
final yMax=yMax,
final yMin=yMin)
"Building supply temperature controller";
Modelica.Blocks.Math.Add dTDis(
final k1=-1)
"Temperature difference on the district side";
Modelica.Blocks.Math.Product pro
"product";
Modelica.Blocks.Math.Gain cp(
final k=cp_default)
"Specific heat multiplier to calculate heat flow rate";
Modelica.Blocks.Continuous.Integrator int(
final k=1)
"Integration";
protected
final parameter MediumSer.ThermodynamicState sta_default=MediumSer.setState_pTX(
T=MediumSer.T_default,
p=MediumSer.p_default,
X=MediumSer.X_default)
"Medium state at default properties";
final parameter Modelica.Units.SI.SpecificHeatCapacity cp_default=MediumSer.specificHeatCapacityCp(
sta_default)
"Specific heat capacity of the fluid";
equation
connect(senTDisSup.port_b, senMasFlo.port_a);
connect(senMasFlo.port_b, conVal.port_a);
connect(conVal.port_b, hex.port_a1);
connect(hex.port_b1, senTDisRet.port_a);
connect(senTBuiRet.port_b, hex.port_a2);
connect(hex.port_b2, senTBuiSup.port_a);
connect(senTBuiSup.T, con.u_m);
connect(TBuiSupSet, con.u_s);
connect(con.y, conVal.y);
connect(senTDisSup.T,dTDis. u2);
connect(senTBuiRet.T,dTDis. u1);
connect(senMasFlo.m_flow, pro.u2);
connect(dTDis.y, pro.u1);
connect(pro.y, cp.u);
connect(cp.y, Q_flow);
connect(cp.y, int.u);
connect(int.y, Q);
end PartialIndirect;
Buildings.DHC.ETS.BaseClasses.Pump_m_flow
Pump with prescribed mass flow rate
Information
This is a steady-state model of a pump with ideally controlled mass flow rate as input signal, and no heat added to the medium.
Extends from Buildings.Fluid.Movers.Preconfigured.FlowControlled_m_flow (Fan or pump with ideally controlled mass flow rate as input signal and pre-configured parameters).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Boolean | addPowerToMedium | false | 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] | |
| PressureDifference | dp_nominal | if rho_default < 500 then 50... | Nominal pressure raise, used for default pressure curve if not specified in record per [Pa] |
| Dynamics | |||
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| 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 | false | = 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] |
| MassFlowRate | m_flow_start | 0 | Initial value of mass flow rate [kg/s] |
| 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 |
| Advanced | |||
| MassFlowRate | m_flow_small | 1E-4*abs(_m_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| Pressure | dpMax | 2*max(eff.per.pressure.dp) | Maximum pressure allowed to operate the model, if exceeded, the simulation stops with an error [Pa] |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at 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 IntegerInput | stage | Stage input signal for the pressure head |
| output RealOutput | y_actual | Actual normalised fan or pump speed that is used for computations [1] |
| output RealOutput | P | Electrical power consumed [W] |
| HeatPort_a | heatPort | Heat dissipation to environment |
| input RealInput | m_flow_in | Prescribed mass flow rate [kg/s] |
| output RealOutput | m_flow_actual | Actual mass flow rate [kg/s] |
Modelica definition
model Pump_m_flow
"Pump with prescribed mass flow rate"
extends Buildings.Fluid.Movers.Preconfigured.FlowControlled_m_flow(
addPowerToMedium=false,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
use_inputFilter=false);
end Pump_m_flow;
Buildings.DHC.ETS.BaseClasses.StratifiedTank
Stratified buffer tank model
Information
This is a four-port tank model based on Buildings.Fluid.Storage.Stratified which includes the following features.
-
The two fluid ports suffixed with
Topare connected to the fluid volume at the top of the tank. -
The two fluid ports suffixed with
Botare connected to the fluid volume at the bottom of the tank. - A unique heat port is exposed as an external connector. It is meant to provide a uniform temperature boundary condition at the external surface of the tank (outside insulation).
- The model outputs the temperature of the fluid volumes at the top and at the bottom of the tank.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | Modelica.Media.Interfaces.Pa... | Medium model | |
| Volume | VTan | Tank volume [m3] | |
| Length | hTan | Height of tank (without insulation) [m] | |
| Length | dIns | Thickness of insulation [m] | |
| ThermalConductivity | kIns | 0.04 | Specific heat conductivity of insulation [W/(m.K)] |
| Integer | nSeg | 3 | Number of volume segments |
| Nominal condition | |||
| MassFlowRate | m_flow_nominal | Nominal mass flow rate [kg/s] | |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package Medium | Medium model | |
| FluidPort_a | port_aTop | Inlet fluid port at tank top |
| FluidPort_b | port_bBot | Outlet fluid port at tank bottom |
| FluidPort_a | port_aBot | Inlet fluid port at tank bottom |
| FluidPort_b | port_bTop | Outlet fluid port at tank top |
| output RealOutput | Ql_flow | Heat loss of tank (positive if heat flows from tank to ambient) [W] |
| output RealOutput | TTop | Fluid temperature at tank top [K] |
| output RealOutput | TBot | Fluid temperature at tank bottom [K] |
| HeatPort_a | heaPorAmb | Heat port at interface with ambient (outside insulation) |
Modelica definition
model StratifiedTank
"Stratified buffer tank model"
replaceable package Medium=Modelica.Media.Interfaces.PartialMedium
"Medium model";
final parameter Boolean allowFlowReversal=true
"= true to allow flow reversal, false restricts to design direction (port_a -> port_b)";
parameter Modelica.Units.SI.Volume VTan "Tank volume";
parameter Modelica.Units.SI.Length hTan "Height of tank (without insulation)";
parameter Modelica.Units.SI.Length dIns "Thickness of insulation";
parameter Modelica.Units.SI.ThermalConductivity kIns=0.04
"Specific heat conductivity of insulation";
parameter Integer nSeg(
min=2)=3
"Number of volume segments";
parameter Modelica.Units.SI.MassFlowRate m_flow_nominal
"Nominal mass flow rate";
// IO CONNECTORS
Modelica.Fluid.Interfaces.FluidPort_a port_aTop(
redeclare final package Medium=Medium,
m_flow(
min=
if allowFlowReversal then
-Modelica.Constants.inf
else
0),
h_outflow(
start=Medium.h_default,
nominal=Medium.h_default))
"Inlet fluid port at tank top";
Modelica.Fluid.Interfaces.FluidPort_b port_bBot(
redeclare final package Medium=Medium,
m_flow(
max=
if allowFlowReversal then
+Modelica.Constants.inf
else
0),
h_outflow(
start=Medium.h_default,
nominal=Medium.h_default))
"Outlet fluid port at tank bottom";
Modelica.Fluid.Interfaces.FluidPort_a port_aBot(
redeclare final package Medium=Medium,
m_flow(
min=
if allowFlowReversal then
-Modelica.Constants.inf
else
0),
h_outflow(
start=Medium.h_default,
nominal=Medium.h_default))
"Inlet fluid port at tank bottom";
Modelica.Fluid.Interfaces.FluidPort_b port_bTop(
redeclare final package Medium=Medium,
m_flow(
max=
if allowFlowReversal then
+Modelica.Constants.inf
else
0),
h_outflow(
start=Medium.h_default,
nominal=Medium.h_default))
"Outlet fluid port at tank top";
Modelica.Blocks.Interfaces.RealOutput Ql_flow(
final unit="W")
"Heat loss of tank (positive if heat flows from tank to ambient)";
Modelica.Blocks.Interfaces.RealOutput TTop(
final unit="K",
displayUnit="degC")
"Fluid temperature at tank top";
Modelica.Blocks.Interfaces.RealOutput TBot(
final unit="K",
displayUnit="degC")
"Fluid temperature at tank bottom";
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a heaPorAmb
"Heat port at interface with ambient (outside insulation)";
// COMPONENTS
Fluid.Storage.Stratified tan(
redeclare final package Medium=Medium,
final m_flow_nominal=m_flow_nominal,
final VTan=VTan,
final hTan=hTan,
final dIns=dIns,
final kIns=kIns,
final nSeg=nSeg)
"Stratified tank";
Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor senTBot
"Tank bottom temperature";
Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor senTTop
"Tank top temperature";
protected
Modelica.Thermal.HeatTransfer.Components.ThermalCollector theCol(
m=3)
"Connector to assign multiple heat ports to one heat port";
equation
connect(port_aTop,tan.port_a);
connect(port_bTop,tan.fluPorVol[1]);
connect(tan.port_b,port_bBot);
connect(port_aBot,tan.fluPorVol[nSeg]);
connect(tan.Ql_flow,Ql_flow);
connect(tan.heaPorVol[nSeg],senTBot.port);
connect(tan.heaPorVol[1],senTTop.port);
connect(senTTop.T,TTop);
connect(senTBot.T,TBot);
connect(heaPorAmb,theCol.port_b);
connect(theCol.port_a[1],tan.heaPorTop);
connect(theCol.port_a[2],tan.heaPorSid);
connect(theCol.port_a[3],tan.heaPorBot);
end StratifiedTank;
Buildings.DHC.ETS.BaseClasses.computeCoordinates
Coordinates of evenly distributed boreholes given the number of boreholes
Information
This function computes the coordinates of boreholes evenly
distributed along the x and y axis,
given the number of boreholes (which must be the square of
an integer).
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nBorHol | Number of boreholes | |
| Distance | dxy | 6 | Distance in x-axis (and y-axis) between borehole axes [m] |
Outputs
| Type | Name | Description |
|---|---|---|
| Distance | cooBor[nBorHol, 2] | Coordinates of boreholes [m] |
Modelica definition
function computeCoordinates
"Coordinates of evenly distributed boreholes given the number of boreholes"
extends Modelica.Icons.Function;
input Integer nBorHol
"Number of boreholes";
input Modelica.Units.SI.Distance dxy=6
"Distance in x-axis (and y-axis) between borehole axes";
output Modelica.Units.SI.Distance cooBor[nBorHol,2]
"Coordinates of boreholes";
protected
Integer k=1
"Iteration index";
algorithm
for i in 0:sqrt(
nBorHol)-1 loop
for j in 0:sqrt(
nBorHol)-1 loop
cooBor[k,1] := i*dxy;
cooBor[k,2] := j*dxy;
k := k+1;
end for;
end for;
end computeCoordinates;