modelExpander
Generic expander model
Information
The Expander model represents the expansion of a fluid in a volumetric machine. It is a lumped model based on performance curves. It is characterized by two flow connector for the fluid inlet and outlet and by a mechanical connector for the connection with the generator.
The assumptions for this model are:
- No dynamics ( it is considered negligible when compared to the one characterizing the heat exchanger).
- No thermal energy losses to the environment
- Isentropic efficiency based on empirical performance curve
- Filling factor based on empirical performance curve
Modelling options
In this model, the user has the choice of providing constant isentropic and volumetric efficiencies, or providing performance curves in the form of a Modelica function. The performance curves can be selected from the General tab with the ExpType enumeration variable.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| ExpTypes | ExpType | ExpTypes.UD | |
| Real | epsilon_s | 0.7 | Isentropic Efficiency |
| Real | FF_exp | 1 | Filling factor |
| Modelica.SIunits.Volume | V_s | Swept volume | |
| Initialization | |||
| Real | epsilon_start | 0.5782 | Isentropic Efficiency |
| Real | FF_start | 0.00003915 | Filling factor |
| Modelica.SIunits.Pressure | p_su_start | 23.39e5 | Inlet pressure start value |
| Modelica.SIunits.Pressure | p_ex_start | 1.77175e5 | Outlet pressure start value |
| Modelica.SIunits.Temperature | T_su_start | 423.15 | Inlet temperature start value |
| Medium.SpecificEnthalpy | h_su_start | Medium.specificEnthalpy_pT(p_su_start, T_su_start) | Inlet enthalpy start value |
| Medium.SpecificEnthalpy | h_ex_start | Medium.specificEnthalpy_pT(p_ex_start, T_su_start) | Outlet enthalpy start value |
| Initialization › Intialization options | |||
| Boolean | constPinit | false | if true, sets the evaporating pressure to a constant value at the beginning of the simulation in order to avoid oscillations |
| Boolean | constinit | false | if true, sets the efficiencies to a constant value at the beginning of the simulation |
| Modelica.SIunits.Time | t_init | 10 | if constinit is true, time during which the efficiencies are set to their start values |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Mechanics.Rotational.Interfaces.Flange_b | flange_elc | Flange of shaft | |
| Interfaces.Fluid.FlangeA | InFlow | ||
| Interfaces.Fluid.FlangeB | OutFlow |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.ThermodynamicState | steamIn | Thermodynamic state of the fluid at the inlet | |
| Medium.ThermodynamicState | steamOut | Thermodynamic state of the fluid at the outlet - isentropic | |
| Real | epsilon | ||
| Real | FF | ||
| Real | rpm | ||
| Modelica.SIunits.Frequency | N_rot | ||
| Modelica.SIunits.Power | W_dot | ||
| Modelica.SIunits.VolumeFlowRate | V_dot_su | ||
| Modelica.SIunits.MassFlowRate | M_dot | ||
| Medium.Density | rho_su | ||
| Medium.SpecificEntropy | s_su | ||
| Medium.SpecificEnthalpy | h_su | ||
| Medium.SpecificEnthalpy | h_ex | ||
| Medium.AbsolutePressure | p_su | ||
| Medium.AbsolutePressure | p_ex | ||
| Medium.SpecificEnthalpy | h_ex_s |
Contents
| Name | Description |
|---|---|
| Medium |