Buildings.Fluid.HeatExchangers.DXCoils.AirCooled
Air-cooled DX package unit
Information
This package contains air-cooled DX coil models, including single-speed, multi-stage, and variable-speed DX coil models.Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
| Name | Description |
|---|---|
 MultiStage
|
Multi-stage DX cooling coil |
 SingleSpeed
|
Single speed DX cooling coil |
 VariableSpeed
|
Variable speed DX cooling coil |
 Data
|
Package with performance data for DX cooling coil |
 Examples
|
Package with example of DX cooling coil models |
| Validation
|
Collection of validation models |
Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.MultiStage
Multi-stage DX cooling coil
Information
This model can be used to simulate an air-cooled DX cooling coil with multiple operating stages. Depending on the used performance curves, each stage could be a different compressor speed, or a different mode of operation, such as with or without hot gas reheat.
See Buildings.Fluid.HeatExchangers.DXCoils.UsersGuide for an explanation of the model.
Extends from Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialDXCoil (Partial model for DX coil).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialCondensingGases | Medium in the component | |
| Boolean | use_mCon_flow | false | Set to true to enable connector for the condenser mass flow rate |
| String | substanceName | "water" | Name of species substance |
| Nominal condition | |||
| PressureDifference | dp_nominal | Pressure difference [Pa] | |
| 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] |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Boolean | from_dp | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics | |||
| Nominal condition | |||
| Time | tau | 30 | Time constant at nominal flow (if energyDynamics <> SteadyState) [s] |
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Moisture balance | |||
| Boolean | computeReevaporation | true | Set to true to compute reevaporation of water that accumulated on coil |
| 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 |
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 | TConIn | Outside air dry bulb temperature for an air cooled condenser or wetbulb temperature for an evaporative cooled condenser [K] |
| input RealInput | mCon_flow | Water mass flow rate for condenser [kg/s] |
| output RealOutput | P | Electrical power consumed by the unit [W] |
| output RealOutput | QSen_flow | Sensible heat flow rate [W] |
| output RealOutput | QLat_flow | Latent heat flow rate [W] |
| input IntegerInput | stage | Stage of cooling coil (0: off, 1: first stage, 2: second stage...) |
Modelica definition
model MultiStage "Multi-stage DX cooling coil"
extends Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialDXCoil(
dxCoo(final variableSpeedCoil=false,
wetCoi(redeclare Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.CoolingCapacityAirCooled
cooCap),
dryCoi(redeclare Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.CoolingCapacityAirCooled
cooCap)),
redeclare Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.Data.Generic.DXCoil
datCoi,
use_mCon_flow=false);
Modelica.Blocks.Interfaces.IntegerInput stage
"Stage of cooling coil (0: off, 1: first stage, 2: second stage...)";
BaseClasses.SpeedSelect speSel(nSta=datCoi.nSta, speSet=datCoi.sta.spe);
Modelica.Blocks.Math.IntegerToBoolean onSwi(final threshold=1)
"On/off switch";
equation
connect(onSwi.y, eva.on);
connect(onSwi.u, stage);
connect(stage, speSel.stage);
connect(speSel.speRat, dxCoo.speRat);
connect(stage, dxCoo.stage);
end MultiStage;
Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.SingleSpeed
Single speed DX cooling coil
Information
This model can be used to simulate an air-cooled DX cooling coil with single speed compressor.
See Buildings.Fluid.HeatExchangers.DXCoils.UsersGuide for an explanation of the model.
Extends from Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialDXCoil (Partial model for DX coil).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialCondensingGases | Medium in the component | |
| Boolean | use_mCon_flow | false | Set to true to enable connector for the condenser mass flow rate |
| String | substanceName | "water" | Name of species substance |
| Nominal condition | |||
| PressureDifference | dp_nominal | Pressure difference [Pa] | |
| 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] |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Boolean | from_dp | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics | |||
| Nominal condition | |||
| Time | tau | 30 | Time constant at nominal flow (if energyDynamics <> SteadyState) [s] |
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Moisture balance | |||
| Boolean | computeReevaporation | true | Set to true to compute reevaporation of water that accumulated on coil |
| 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 |
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 | TConIn | Outside air dry bulb temperature for an air cooled condenser or wetbulb temperature for an evaporative cooled condenser [K] |
| input RealInput | mCon_flow | Water mass flow rate for condenser [kg/s] |
| output RealOutput | P | Electrical power consumed by the unit [W] |
| output RealOutput | QSen_flow | Sensible heat flow rate [W] |
| output RealOutput | QLat_flow | Latent heat flow rate [W] |
| input BooleanInput | on | Set to true to enable compressor, or false to disable compressor |
Modelica definition
model SingleSpeed "Single speed DX cooling coil"
extends Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialDXCoil(
dxCoo(final variableSpeedCoil=false,
wetCoi(redeclare Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.CoolingCapacityAirCooled
cooCap),
dryCoi(redeclare Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.CoolingCapacityAirCooled
cooCap)),
redeclare Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.Data.Generic.DXCoil
datCoi,
use_mCon_flow=false);
Modelica.Blocks.Sources.Constant speRat(final k=1) "Speed ratio";
Modelica.Blocks.Interfaces.BooleanInput on
"Set to true to enable compressor, or false to disable compressor";
protected
Modelica.Blocks.Math.BooleanToInteger onSwi(
final integerTrue=1,
final integerFalse=0) "On/off switch";
initial equation
assert(datCoi.nSta == 1, "Must have one stage only for single speed performance data");
equation
connect(speRat.y, dxCoo.speRat);
connect(eva.on, on);
connect(on, onSwi.u);
connect(onSwi.y, dxCoo.stage);
end SingleSpeed;
Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.VariableSpeed
Variable speed DX cooling coil
Information
This model can be used to simulate an air-cooled DX cooling coil with continuously variable speed compressors. The control input is the speed ratio. The coil will switch off if the speed ratio is below a minimum value.
See Buildings.Fluid.HeatExchangers.DXCoils.UsersGuide for an explanation of the model.
Extends from Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialDXCoil (Partial model for DX coil).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialCondensingGases | Medium in the component | |
| Boolean | use_mCon_flow | false | Set to true to enable connector for the condenser mass flow rate |
| String | substanceName | "water" | Name of species substance |
| Real | minSpeRat | Minimum speed ratio | |
| Real | speRatDeaBan | 0.05 | Deadband for minimum speed ratio |
| Nominal condition | |||
| PressureDifference | dp_nominal | Pressure difference [Pa] | |
| 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] |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Boolean | from_dp | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics | |||
| Nominal condition | |||
| Time | tau | 30 | Time constant at nominal flow (if energyDynamics <> SteadyState) [s] |
| Conservation equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Moisture balance | |||
| Boolean | computeReevaporation | true | Set to true to compute reevaporation of water that accumulated on coil |
| 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 |
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 | TConIn | Outside air dry bulb temperature for an air cooled condenser or wetbulb temperature for an evaporative cooled condenser [K] |
| input RealInput | mCon_flow | Water mass flow rate for condenser [kg/s] |
| output RealOutput | P | Electrical power consumed by the unit [W] |
| output RealOutput | QSen_flow | Sensible heat flow rate [W] |
| output RealOutput | QLat_flow | Latent heat flow rate [W] |
| input RealInput | speRat | Speed ratio |
Modelica definition
model VariableSpeed "Variable speed DX cooling coil"
extends Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialDXCoil(
dxCoo(final variableSpeedCoil=true,
wetCoi(redeclare Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.CoolingCapacityAirCooled
cooCap),
dryCoi(redeclare Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.CoolingCapacityAirCooled
cooCap)),
redeclare Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.Data.Generic.DXCoil
datCoi,
use_mCon_flow=false);
parameter Real minSpeRat(min=0,max=1) "Minimum speed ratio";
parameter Real speRatDeaBan= 0.05 "Deadband for minimum speed ratio";
Modelica.Blocks.Interfaces.RealInput speRat "Speed ratio";
protected
Modelica.Blocks.Logical.Hysteresis deaBan(
uLow=minSpeRat - speRatDeaBan/2,
uHigh=minSpeRat + speRatDeaBan/2) "Speed ratio deadband";
Modelica.Blocks.Math.BooleanToInteger onSwi(
final integerTrue=1,
final integerFalse=0) "On/off switch";
equation
connect(speRat, dxCoo.speRat);
connect(speRat, deaBan.u);
connect(deaBan.y, eva.on);
connect(onSwi.y, dxCoo.stage);
connect(deaBan.y, onSwi.u);
end VariableSpeed;