Buildings.Templates.Components.Chillers
Chiller models
Information
This package contains models for chillers.
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
| Name | Description |
|---|---|
 Compression
|
Compression chiller |
Buildings.Templates.Components.Chillers.Compression
Compression chiller
Information
This is a model for air-cooled or water-cooled compression chillers
where the capacity and input power are computed by interpolating manufacturer data
along the evaporator entering or leaving temperature, the
condenser entering or leaving temperature and the part load ratio.
The model can be configured to represent either a cooling-only
chiller (have_switchover=false) or a heat-recovery chiller
(have_switchover=true) that can be controlled to track
either a CHW temperature setpoint or a HW temperature setpoint.
This model is a wrapper for Buildings.Fluid.Chillers.ModularReversible.TableData2DLoadDep, which the user may refer to for the modeling assumptions. Note that, by default, internal safeties in this model are disabled.
Control points
The following input and output points are available.
-
On/off command:
y1, DO signal -
For heat recovery chillers only (
have_switchover=true), operating mode command:y1Coo, DO signal, true for cooling, false for heating -
Supply or return CHW temperature setpoint
TChiWatSet, AO signal (the choice between supply and return temperature tracking depends on the parameter:use_TChiWatSupForCtl) - For heat recovery chillers only (
have_switchover=true), supply or return HW temperature setpointTHeaWatSet, AO signal (the choice between supply and return temperature tracking depends on the parameter:use_TChiWatSupForCtl) -
Chiller status:
y1_actual, DI signal -
CHW flow request:
y1ReqFloChiWat, DI signal -
(Only if
typ=Buildings.Templates.Components.Types.Chiller.WaterCooled) CW flow request:y1ReqFloConWat, DI signal
Model parameters
The design parameters and the chiller performance data are specified with an instance of Buildings.Templates.Components.Data.Chiller.
Extends from Buildings.Templates.Components.Interfaces.PartialChiller (Interface class for chiller models).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumChiWat | Water | CHW medium | |
| replaceable package MediumCon | Water | Medium model for condenser cooling fluid | |
| Chiller | dat | Design and operating parameters | |
| HeatFlowRate | QCon_flow_nominal | chi.PEle_nominal - QChiWat_f... | Design condenser heat flow rate [W] |
| Temperature | TConEnt_nominal | if dat.per.use_TConOutForTab... | Design condenser entering fluid temperature [K] |
| Temperature | TConLvg_nominal | if dat.per.use_TConOutForTab... | Design condenser leaving fluid temperature [K] |
| Efficiency | COP_nominal | abs(QChiWat_flow_nominal)/ch... | Coefficient of performance at design cooling conditions [1] |
| Configuration | |||
| Chiller | typ | Type of chiller | |
| Boolean | have_switchover | false | Set to true for heat recovery chiller with built-in switchover |
| Boolean | use_TChiWatSupForCtl | true | Set to true for CHW supply temperature control, false for CHW return temperature control |
| Assumptions | |||
| Boolean | allowFlowReversal1 | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1 |
| Boolean | allowFlowReversal2 | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2 |
| Boolean | have_dpChiWat | true | Set to true for CHW pressure drop computed by this model, false for external computation |
| Boolean | have_dpCon | true | Set to true for condenser cooling fluid pressure drop computed by this model, false for external computation |
| Advanced | |||
| MassFlowRate | m1_flow_small | 1E-4*abs(m1_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| MassFlowRate | m2_flow_small | 1E-4*abs(m2_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 |
| Dynamics | |||
| Nominal condition | |||
| Time | tau | 30 | Time constant at nominal flow, used if energy or mass balance is dynamic [s] |
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPort_a | port_a1 | Fluid connector a1 (positive design flow direction is from port_a1 to port_b1) |
| FluidPort_b | port_b1 | Fluid connector b1 (positive design flow direction is from port_a1 to port_b1) |
| FluidPort_a | port_a2 | Fluid connector a2 (positive design flow direction is from port_a2 to port_b2) |
| FluidPort_b | port_b2 | Fluid connector b2 (positive design flow direction is from port_a2 to port_b2) |
| Bus | bus | Control bus |
Modelica definition
model Compression
"Compression chiller"
extends Buildings.Templates.Components.Interfaces.PartialChiller(
final COP_nominal=abs(QChiWat_flow_nominal) / chi.PEle_nominal,
final QCon_flow_nominal=chi.PEle_nominal - QChiWat_flow_nominal,
final TConEnt_nominal=if dat.per.use_TConOutForTab then
dat.TCon_nominal - QCon_flow_nominal / mCon_flow_nominal / cpCon_default
else dat.TCon_nominal,
final TConLvg_nominal=if dat.per.use_TConOutForTab then dat.TCon_nominal else
dat.TCon_nominal + QCon_flow_nominal / mCon_flow_nominal / cpCon_default);
Controls.StatusEmulator y1_actual
"Compute chiller status";
Buildings.Controls.OBC.CDL.Routing.BooleanExtractSignal reqFloConWat(
final nin=1,
final nout=1,
final extract={1})
if typ == Buildings.Templates.Components.Types.Chiller.WaterCooled
"Compute CW flow request";
Buildings.Controls.OBC.CDL.Logical.Not off
"Return true if status is off";
Buildings.Controls.OBC.CDL.Logical.TrueDelay delOff(
delayTime=180)
"Delay off status";
Buildings.Controls.OBC.CDL.Logical.Not reqFlo
"Compute flow request";
Buildings.Fluid.Chillers.ModularReversible.TableData2DLoadDep chi(
redeclare final package MediumCon=MediumCon,
redeclare final package MediumEva=MediumChiWat,
final use_TLoaLvgForCtl=use_TChiWatSupForCtl,
allowDifferentDeviceIdentifiers=true,
final allowFlowReversalCon=allowFlowReversal1,
final allowFlowReversalEva=allowFlowReversal2,
final datCoo=dat.per,
final P_min=dat.P_min,
final dpCon_nominal=if have_dpCon then dpCon_nominal else 0,
final dpEva_nominal=if have_dpChiWat then dpChiWat_nominal else 0,
dTCon_nominal=0,
final dTEva_nominal=TChiWatSup_nominal - TChiWatRet_nominal,
final energyDynamics=energyDynamics,
final have_switchover=have_switchover,
final mCon_flow_nominal=mCon_flow_nominal,
final mEva_flow_nominal=mChiWat_flow_nominal,
final QCoo_flow_nominal=QChiWat_flow_nominal,
final show_T=show_T,
final tauCon=tau,
final tauEva=tau,
final TConCoo_nominal=dat.TCon_nominal,
final TEvaCoo_nominal=if dat.per.use_TEvaOutForTab then TChiWatSup_nominal else TChiWatRet_nominal,
use_intSafCtr=false)
"Chiller";
equation
connect(bus.y1, y1_actual.y1);
connect(y1_actual.y1_actual, bus.y1_actual);
connect(reqFloConWat.y[1], bus.y1ReqFloConWat);
connect(y1_actual.y1_actual, off.u);
connect(off.y, delOff.u);
connect(delOff.y, reqFlo.u);
connect(reqFlo.y, bus.y1ReqFloChiWat);
connect(reqFlo.y, reqFloConWat.u[1]);
connect(port_a2, chi.port_a2);
connect(chi.port_b2, port_b2);
connect(port_a1, chi.port_a1);
connect(chi.port_b1, port_b1);
connect(bus.y1, chi.on);
connect(bus.TChiWatSet, chi.TChwSet);
connect(bus.y1Coo, chi.coo);
connect(bus.THeaWatSet, chi.THwSet);
end Compression;