Buildings.Fluid.DXSystems.Cooling.AirSource
Air source DX coils
Information
This package contains air source DX coil models, including single-speed, multi-stage, and variable-speed DX coil models.
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 coils |
 Examples
|
Package with example of DX cooling coil models |
| Validation
|
Collection of validation models |
Buildings.Fluid.DXSystems.Cooling.AirSource.MultiStage
Multi-stage DX cooling coil
Information
This model can be used to simulate an air source 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.DXSystems.Cooling.UsersGuide for an explanation of the model.
Extends from Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialDXCoolingCoil (Partial model for DX cooling coil).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| DXCoil | datCoi | redeclare Buildings.Fluid.DX... | Performance data |
| 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 |
| 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 | TOut | 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.DXSystems.Cooling.BaseClasses.PartialDXCoolingCoil(
dxCoi(
final variableSpeedCoil=false,
wetCoi(redeclare Buildings.Fluid.DXSystems.BaseClasses.CapacityAirSource
coiCap),
dryCoi(redeclare Buildings.Fluid.DXSystems.BaseClasses.CapacityAirSource
coiCap)),
use_mCon_flow=false);
Modelica.Blocks.Interfaces.IntegerInput stage
"Stage of cooling coil (0: off, 1: first stage, 2: second stage...)";
Buildings.Fluid.DXSystems.Cooling.BaseClasses.SpeedSelect speSel(
final nSta=datCoi.nSta, speSet=datCoi.sta.spe)
"Normalize the speed signal based on the compressor stage input";
Modelica.Blocks.Math.IntegerToBoolean onSwi(
final threshold=1)
"On/off switch";
equation
connect(onSwi.y, watVapEva.on);
connect(onSwi.u, stage);
connect(stage, speSel.stage);
connect(speSel.speRat,dxCoi.speRat);
connect(stage,dxCoi.stage);
end MultiStage;
Buildings.Fluid.DXSystems.Cooling.AirSource.SingleSpeed
Single speed DX cooling coil
Information
This model can be used to simulate an air source DX cooling coil with single speed compressor.
See Buildings.Fluid.DXSystems.Cooling.UsersGuide for an explanation of the model.
Extends from Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialDXCoolingCoil (Partial model for DX cooling coil).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| DXCoil | datCoi | redeclare Buildings.Fluid.DX... | Performance data |
| 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 |
| 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 | TOut | 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.DXSystems.Cooling.BaseClasses.PartialDXCoolingCoil(
dxCoi(
final variableSpeedCoil=false,
wetCoi(redeclare Buildings.Fluid.DXSystems.BaseClasses.CapacityAirSource
coiCap),
dryCoi(redeclare Buildings.Fluid.DXSystems.BaseClasses.CapacityAirSource
coiCap)),
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,dxCoi.speRat);
connect(watVapEva.on, on);
connect(on, onSwi.u);
connect(onSwi.y,dxCoi.stage);
end SingleSpeed;
Buildings.Fluid.DXSystems.Cooling.AirSource.VariableSpeed
Variable speed DX cooling coil
Information
This model can be used to simulate an air source 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.DXSystems.Cooling.UsersGuide for an explanation of the model.
Extends from Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialDXCoolingCoil (Partial model for DX cooling coil).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| DXCoil | datCoi | redeclare Buildings.Fluid.DX... | Performance data |
| 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 |
| 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 | TOut | 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 [1] |
Modelica definition
model VariableSpeed "Variable speed DX cooling coil"
extends Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialDXCoolingCoil(
dxCoi(
final variableSpeedCoil=true,
wetCoi(redeclare Buildings.Fluid.DXSystems.BaseClasses.CapacityAirSource
coiCap),
dryCoi(redeclare Buildings.Fluid.DXSystems.BaseClasses.CapacityAirSource
coiCap)),
use_mCon_flow=false);
parameter Real minSpeRat(
final min=0,
final max=1)
"Minimum speed ratio";
parameter Real speRatDeaBan= 0.05
"Deadband for minimum speed ratio";
Modelica.Blocks.Interfaces.RealInput speRat(
final unit="1",
displayUnit="1")
"Speed ratio";
protected
Modelica.Blocks.Logical.Hysteresis deaBan(
final uLow=minSpeRat - speRatDeaBan/2,
final uHigh=minSpeRat + speRatDeaBan/2)
"Speed ratio deadband";
Modelica.Blocks.Math.BooleanToInteger onSwi(
final integerTrue=1,
final integerFalse=0)
"On/off switch";
equation
connect(speRat,dxCoi.speRat);
connect(speRat, deaBan.u);
connect(deaBan.y, watVapEva.on);
connect(onSwi.y,dxCoi.stage);
connect(deaBan.y, onSwi.u);
end VariableSpeed;