Buildings.Fluid.DXSystems.Heating.AirSource
Air source DX coils
Information
This package contains water source DX coil models.
Package Content
| Name | Description |
|---|---|
 SingleSpeed
|
Single speed DX heating coil |
 Data
|
Package with performance data for DX heating coils |
 Examples
|
Collection of models that illustrate model use and test models |
| Validation
|
Collection of validation models |
Buildings.Fluid.DXSystems.Heating.AirSource.SingleSpeed
Single speed DX heating coil
Information
This model can be used to simulate an air-source DX heating coil with single speed compressor.
See Buildings.Fluid.DXSystems.Heating.UsersGuide for an explanation of the model.
Extends from Buildings.Fluid.DXSystems.Heating.BaseClasses.PartialDXHeatingCoil (Partial model for DX heating coil).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialCondensingGases | Medium in the component | |
| DXCoil | datCoi | Performance data | |
| 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] |
| TemperatureDifference | dTHys | 0.5 | Temperature comparison for hysteresis [K] |
| 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 |
| 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 | phi | Outdoor air relative humidity at evaporator inlet (0...1) [1] |
| output RealOutput | P | Electrical power consumed [W] |
| output RealOutput | QSen_flow | Sensible 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 heating coil"
extends Buildings.Fluid.DXSystems.Heating.BaseClasses.PartialDXHeatingCoil;
Modelica.Blocks.Interfaces.BooleanInput on
"Set to true to enable compressor, or false to disable compressor";
protected
Modelica.Blocks.Sources.Constant speRat(
final k=1)
"Speed ratio 1 constant source";
Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToReaOn
"Convert Boolean enable signal to Real value 1, disable to Real value 0";
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(on, onSwi.u);
connect(onSwi.y,dxCoi.stage);
connect(on, booToReaOn.u);
connect(booToReaOn.y, defCap.uSpe);
end SingleSpeed;