modelOpenTank
Lumped open tank model with an imposed constant pressure
Information
The model OpenTank describes the storage of fluid in liquid phase in an open tank.
Pressure and enthalpy are selected as state variables.
The assumptions for this model are:
- The model is based on dynamic mass and energy balance
- Constant external pressure
- The static pressure head due to the liquid level is taken into account
- Thermal energy transfer through the lateral surface is ensured by the TankWall connector. The actual heat flow is computed by the thermal energy model.
- Minimum liquid level with respect to tank height= 0
- Maximum liquid level with respect to tank height= 1
The model comprises two flow connectors and one lumped thermal port connector. During normal operation the fluid enters the model from the InFlow connector and exits from the OutFlow connector. In case of flow reversal the fluid direction is inversed
Modelling options
In the General tab the following options are available:
- Medium: the user has the possibility to easily switch Medium.
- HeatTransfer: selection between the different heat transfer models available in ThermoCycle
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | g | Modelica.Constants.g_n | |
| Real | pi | Modelica.Constants.pi | pi-greco |
| Real | H_D | 2.5 | Height to diameter ratio |
| Modelica.SIunits.Volume | V_tank | 4 | Volume of the Tank |
| Modelica.SIunits.Length | r_int | ((V_tank/(H_D)*4/pi)^(1/3))/2 | Internal tank radius |
| Modelica.SIunits.Length | D_int | r_int*2 | Internal tank Diameter |
| Modelica.SIunits.Length | H | V_tank/(A_cross) | Tank Height |
| Modelica.SIunits.Area | A_lateral | pi*H*D_int | Lateral External Area |
| Modelica.SIunits.Area | A_cross | pi*r_int^2 | Cross section of the tank External Area |
| Modelica.SIunits.Area | Atot_tank | A_lateral + 2*A_cross | Total External Area (lateral + bottom + top) |
| Modelica.SIunits.Pressure | p_ext | 3e5 | External pressure imposed to the system |
| Modelica.SIunits.CoefficientOfHeatTransfer | Unom | 1 | Nominal Heat transfer coefficient for the fluid |
| Initialization | |||
| Modelica.SIunits.Temperature | Tstart | 100 + 273.15 | Initial temperature |
| Modelica.SIunits.Pressure | pstart | 2e5 | Initial temperature |
| Modelica.SIunits.SpecificEnthalpy | hstart | Medium.specificEnthalpy_pTX(pstart, Tstart, fill(0, 0)) | Start value of enthalpy vector (initialized by default) |
| Real | L_lstart | 0.3 | Start value for the liquid level with respect to the height of the tank,Min=0,Max=1 |
| Modelica.SIunits.MassFlowRate | Mdotnom | 2 | Nominal fluid flow rate |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| ThermoCycle.Interfaces.Fluid.FlangeA | InFlow | ||
| Interfaces.Fluid.FlangeB | OutFlow | ||
| Modelica.Blocks.Interfaces.RealOutput | Level | ||
| Interfaces.HeatTransfer.ThermalPortL | TankWall |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| HeatTransfer | heatTransfer | ||
| Medium.ThermodynamicState | fluidState | ||
| Medium.AbsolutePressure | p | ||
| Modelica.SIunits.Volume | V_l | Volume of the liquid | |
| Modelica.SIunits.Area | A_l | Lateral area of the tank occupied by the fluid | |
| Real | L_l | Height of the liquid with respect to tank height | |
| Modelica.SIunits.Mass | M_l | Liquid Mass | |
| Medium.SpecificEnthalpy | h | Fluid specific enthalpy | |
| Modelica.SIunits.SpecificEnthalpy | h_su | Enthalpy state variable at inlet node | |
| Modelica.SIunits.SpecificEnthalpy | h_ex | Enthalpy state variable at outlet node | |
| Medium.Density | rho | Fluid density | |
| Medium.Temperature | T | Fluid temperature | |
| Modelica.SIunits.MassFlowRate | M_dot_su | ||
| Modelica.SIunits.MassFlowRate | M_dot_ex | ||
| Modelica.SIunits.DerDensityByEnthalpy | drdh | Derivative of average density by enthalpy | |
| Modelica.SIunits.HeatFlux | qdot | heat flux with the external ambient | |
| Real | dMdt |
Contents
| Name | Description |
|---|---|
| Medium | |
 HeatTransfer |