Base classes used in the Vessels package (only of interest to build new component models)

Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).

Name | Description |
---|---|

PartialLumpedVessel | Lumped volume with a vector of fluid ports and replaceable heat transfer model |

HeatTransfer | HeatTransfer models for vessels |

VesselPortsData | Data to describe inlet/outlet ports at vessels: diameter -- Inner (hydraulic) diameter of inlet/outlet port height -- Height over the bottom of the vessel zeta_out -- Hydraulic resistance out of vessel, default 0.5 for small diameter mounted flush with the wall zeta_in -- Hydraulic resistance into vessel, default 1.04 for small diameter mounted flush with the wall |

VesselFluidPorts_a | Fluid connector with filled, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging) |

VesselFluidPorts_b | Fluid connector with outlined, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging) |

Lumped volume with a vector of fluid ports and replaceable heat transfer model

This base class extends PartialLumpedVolume with a vector of fluid ports and a replaceable wall HeatTransfer model.

The following modeling assumption are made:

- homogeneous medium, i.e., phase separation is not taken into account,
- no kinetic energy in the fluid, i.e., kinetic energy dissipates into the internal energy,
- pressure loss definitions at vessel ports assume incompressible fluid,
- outflow of ambient media is prevented at each port assuming check valve behavior.
If
`fluidlevel < portsData_height[i]`

and`ports[i].p < vessel_ps_static[i]`

mass flow at the port is set to 0.

Each port has a (hydraulic) diameter and a height above the bottom of the vessel, which can be configured using the ** portsData** record.
Alternatively the impact of port geometries can be neglected with

`use_portsData=false`

. This might be useful for early
design studies. Note that this means to assume an infinite port diameter at the bottom of the vessel.
Pressure drops and heights of the ports as well as kinetic and potential energy fluid entering or leaving the vessel are neglected then.
The following variables need to be defined by an extending model:

`input fluidVolume`

, the volume of the fluid in the vessel,`vessel_ps_static[nPorts]`

, the static pressures inside the vessel at the height of the corresponding ports, at zero flow velocity, and`Wb_flow`

, work term of the energy balance, e.g., p*der(V) if the volume is not constant or stirrer power.

An extending model should define:

`parameter vesselArea`

(default: Modelica.Constants.inf m2), the area of the vessel, to be related to cross flow areas of the ports for the consideration of dynamic pressure effects.

Optionally the fluid level may vary in the vessel, which effects the flow through the ports at configurable `portsData_height[nPorts]`

.
This is why an extending model with varying fluid level needs to define:

`input fluidLevel (default: 0m)`

, the level the fluid in the vessel, and`parameter fluidLevel_max (default: 1m)`

, the maximum level that must not be exceeded. Ports at or above fluidLevel_max can only receive inflow.

An extending model should not access the `portsData`

record defined in the configuration dialog,
as an access to `portsData`

may fail for `use_portsData=false`

or `nPorts=0`

.

Instead the predefined variables

`portsData_diameter[nPorts]`

,`portsData_height[nPorts]`

,`portsData_zeta_in[nPorts]`

, and`portsData_zeta_out[nPorts]`

should be used if these values are needed.

Extends from Modelica.Fluid.Interfaces.PartialLumpedVolume (Lumped volume with mass and energy balance).

Name | Description |
---|---|

replaceable package Medium | Medium in the component |

Ports | |

use_portsData | = false to neglect pressure loss and kinetic energy |

portsData[if use_portsData then nPorts else 0] | Data of inlet/outlet ports |

Assumptions | |

Dynamics | |

energyDynamics | Formulation of energy balance |

massDynamics | Formulation of mass balance |

Heat transfer | |

use_HeatTransfer | = true to use the HeatTransfer model |

replaceable model HeatTransfer | Wall heat transfer |

Initialization | |

p_start | Start value of pressure [Pa] |

use_T_start | = true, use T_start, otherwise h_start |

T_start | Start value of temperature [K] |

h_start | Start value of specific enthalpy [J/kg] |

X_start[Medium.nX] | Start value of mass fractions m_i/m [kg/kg] |

C_start[Medium.nC] | Start value of trace substances |

Advanced | |

Port properties | |

m_flow_nominal | Nominal value for mass flow rates in ports [kg/s] |

m_flow_small | Regularization range at zero mass flow rate [kg/s] |

use_Re | = true, if turbulent region is defined by Re, otherwise by m_flow_small |

Name | Description |
---|---|

ports[nPorts] | Fluid inlets and outlets |

heatPort | |

Assumptions | |

Heat transfer | |

replaceable model HeatTransfer | Wall heat transfer |

Data to describe inlet/outlet ports at vessels: diameter -- Inner (hydraulic) diameter of inlet/outlet port height -- Height over the bottom of the vessel zeta_out -- Hydraulic resistance out of vessel, default 0.5 for small diameter mounted flush with the wall zeta_in -- Hydraulic resistance into vessel, default 1.04 for small diameter mounted flush with the wall

This record describes the **ports** of a **vessel**. The variables in it are mostly self-explanatory (see list below); only the ζ
loss factors are discussed further. All data is quoted from Idelchik (1994).

If a **straight pipe with constant cross section is mounted flush with the wall**, its outlet pressure loss coefficient will be `ζ = 0.5`

(Idelchik, p. 160, Diagram 3-1, paragraph 2).

If a **straight pipe with constant cross section is mounted into a vessel such that the entrance into it is at a distance** `b`

from the wall (inside) the following table can be used. Herein, δ is the tube wall thickness (Idelchik, p. 160, Diagram 3-1, paragraph 1).

b / D_hyd | ||||||
---|---|---|---|---|---|---|

0.000 | 0.005 | 0.020 | 0.100 | 0.500-∞ | ||

δ / D_hyd | 0.000 | 0.50 | 0.63 | 0.73 | 0.86 | 1.00 |

0.008 | 0.50 | 0.55 | 0.62 | 0.74 | 0.88 | |

0.016 | 0.50 | 0.51 | 0.55 | 0.64 | 0.77 | |

0.024 | 0.50 | 0.50 | 0.52 | 0.58 | 0.68 | |

0.040 | 0.50 | 0.50 | 0.51 | 0.51 | 0.54 |

If a **straight pipe with a circular bellmouth inlet (collector) without baffle is mounted flush with the wall** then its pressure loss coefficient can be established from the following table. Herein, r is the radius of the bellmouth inlet surface (Idelchik, p. 164 f., Diagram 3-4, paragraph b)

r / D_hyd | ||||||
---|---|---|---|---|---|---|

0.01 | 0.03 | 0.05 | 0.08 | 0.16 | ≥0.20 | |

ζ | 0.44 | 0.31 | 0.22 | 0.15 | 0.06 | 0.03 |

If a **straight pipe with a circular bellmouth inlet (collector) without baffle is mounted at a distance from a wall** then its pressure loss coefficient can be established from the following table. Herein, r is the radius of the bellmouth inlet surface (Idelchik, p. 164 f., Diagram 3-4, paragraph a)

r / D_hyd | ||||||
---|---|---|---|---|---|---|

0.01 | 0.03 | 0.05 | 0.08 | 0.16 | ≥0.20 | |

ζ | 0.87 | 0.61 | 0.40 | 0.20 | 0.06 | 0.03 |

If a **straight pipe with constant circular cross section is mounted flush with the wall**, its vessel inlet pressure loss coefficient will be according to the following table (Idelchik, p. 209 f., Diagram 4-2 with `A_port/A_vessel = 0`

and Idelchik, p. 640, Diagram 11-1, graph a). According to the text, `m = 9`

is appropriate for fully developed turbulent flow.

m | ||||||
---|---|---|---|---|---|---|

1.0 | 2.0 | 3.0 | 4.0 | 7.0 | 9.0 | |

ζ | 2.70 | 1.50 | 1.25 | 1.15 | 1.06 | 1.04 |

For larger port diameters, relative to the area of the vessel, the inlet pressure loss coefficient will be according to the following table (Idelchik, p. 209 f., Diagram 4-2 with `m = 7`

).

A_port / A_vessel | ||||||
---|---|---|---|---|---|---|

0.0 | 0.1 | 0.2 | 0.4 | 0.6 | 0.8 | |

ζ | 1.04 | 0.84 | 0.67 | 0.39 | 0.18 | 0.06 |

- Idelchik I.E. (1994):
**Handbook of Hydraulic Resistance**. 3rd edition, Begell House, ISBN 0-8493-9908-4

Extends from Modelica.Icons.Record (Icon for records).

Name | Description |
---|---|

diameter | Inner (hydraulic) diameter of inlet/outlet port [m] |

height | Height over the bottom of the vessel [m] |

zeta_out | Hydraulic resistance out of vessel, default 0.5 for small diameter mounted flush with the wall |

zeta_in | Hydraulic resistance into vessel, default 1.04 for small diameter mounted flush with the wall |

Fluid connector with filled, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging)

Extends from Interfaces.FluidPort (Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)).

Name | Description |
---|---|

replaceable package Medium | Medium model |

Name | Description |
---|---|

m_flow | Mass flow rate from the connection point into the component [kg/s] |

p | Thermodynamic pressure in the connection point [Pa] |

h_outflow | Specific thermodynamic enthalpy close to the connection point if m_flow < 0 [J/kg] |

Xi_outflow[Medium.nXi] | Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0 [kg/kg] |

C_outflow[Medium.nC] | Properties c_i/m close to the connection point if m_flow < 0 |

Fluid connector with outlined, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging)

Extends from Interfaces.FluidPort (Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)).

Name | Description |
---|---|

replaceable package Medium | Medium model |

Name | Description |
---|---|

m_flow | Mass flow rate from the connection point into the component [kg/s] |

p | Thermodynamic pressure in the connection point [Pa] |

h_outflow | Specific thermodynamic enthalpy close to the connection point if m_flow < 0 [J/kg] |

Xi_outflow[Medium.nXi] | Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0 [kg/kg] |

C_outflow[Medium.nC] | Properties c_i/m close to the connection point if m_flow < 0 |