Package Modelica.​Fluid.​Vessels.​BaseClasses
Base classes used in the Vessels package (only of interest to build new component models)

Information

This icon shall be used for a package/library that contains base models and classes, respectively.

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

Package Contents

NameDescription
HeatTransferHeatTransfer models for vessels
PartialLumpedVesselLumped volume with a vector of fluid ports and replaceable heat transfer model
VesselFluidPorts_aFluid connector with filled, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging)
VesselFluidPorts_bFluid connector with outlined, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging)
VesselPortsDataData 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

Partial Model Modelica.​Fluid.​Vessels.​BaseClasses.​PartialLumpedVessel
Lumped volume with a vector of fluid ports and replaceable heat transfer model

Information

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

The following modeling assumption are made:

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:

An extending model should define:

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:

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

should be used if these values are needed.

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

Parameters

TypeNameDefaultDescription
DynamicsenergyDynamicssystem.​energyDynamicsFormulation of energy balance
DynamicsmassDynamicssystem.​massDynamicsFormulation of mass balance
final DynamicssubstanceDynamicsmassDynamicsFormulation of substance balance
final DynamicstraceDynamicsmassDynamicsFormulation of trace substance balance
AbsolutePressurep_startsystem.​p_startStart value of pressure
Booleanuse_T_starttrue= true, use T_start, otherwise h_start
TemperatureT_startif use_T_start then system.T_start else Medium.temperature_phX(p_start, h_start, X_start)Start value of temperature
SpecificEnthalpyh_startif use_T_start then Medium.specificEnthalpy_pTX(p_start, T_start, X_start) else Medium.h_defaultStart value of specific enthalpy
MassFractionX_start[Medium.nX]Medium.​X_defaultStart value of mass fractions m_i/m
ExtraPropertyC_start[Medium.nC]Medium.​C_defaultStart value of trace substances
IntegernPorts0Number of ports
Booleanuse_portsDatatrue= false to neglect pressure loss and kinetic energy
VesselPortsDataportsData[if use_portsData then nPorts else 0] Data of inlet/outlet ports
MassFlowRatem_flow_nominalif system.use_eps_Re then system.m_flow_nominal else 100 * system.m_flow_smallNominal value for mass flow rates in ports
MassFlowRatem_flow_smallif system.use_eps_Re then system.eps_m_flow * m_flow_nominal else system.m_flow_smallRegularization range at zero mass flow rate
Booleanuse_Resystem.​use_eps_Re= true, if turbulent region is defined by Re, otherwise by m_flow_small
Booleanuse_HeatTransferfalse= true to use the HeatTransfer model

Connectors

TypeNameDescription
VesselFluidPorts_bports[nPorts]Fluid inlets and outlets
HeatPort_aheatPort 

Record Modelica.​Fluid.​Vessels.​BaseClasses.​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

Information

Vessel Port Data

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).

Outlet Coefficients

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).

Pressure loss coefficients for outlets, entrance at a distance from wall
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)

Pressure loss coefficients for outlets, bellmouth flush with wall
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)

Pressure loss coefficients for outlets, bellmouth at a distance of wall
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

Inlet Coefficients

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.

Pressure loss coefficients for inlets, circular tube flush with wall
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).

Pressure loss coefficients for inlets, circular tube flush with wall
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

References

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).

Fields

TypeNameDescription
parameter DiameterdiameterInner (hydraulic) diameter of inlet/outlet port
parameter HeightheightHeight over the bottom of the vessel
parameter Realzeta_outHydraulic resistance out of vessel, default 0.5 for small diameter mounted flush with the wall
parameter Realzeta_inHydraulic resistance into vessel, default 1.04 for small diameter mounted flush with the wall

Connector Modelica.​Fluid.​Vessels.​BaseClasses.​VesselFluidPorts_a
Fluid connector with filled, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging)

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

Fields

TypeNameDescription
flow MassFlowRatem_flowMass flow rate from the connection point into the component
AbsolutePressurepThermodynamic pressure in the connection point
stream SpecificEnthalpyh_outflowSpecific thermodynamic enthalpy close to the connection point if m_flow < 0
stream MassFractionXi_outflow[Medium.nXi]Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0
stream ExtraPropertyC_outflow[Medium.nC]Properties c_i/m close to the connection point if m_flow < 0

Connector Modelica.​Fluid.​Vessels.​BaseClasses.​VesselFluidPorts_b
Fluid connector with outlined, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging)

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

Fields

TypeNameDescription
flow MassFlowRatem_flowMass flow rate from the connection point into the component
AbsolutePressurepThermodynamic pressure in the connection point
stream SpecificEnthalpyh_outflowSpecific thermodynamic enthalpy close to the connection point if m_flow < 0
stream MassFractionXi_outflow[Medium.nXi]Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0
stream ExtraPropertyC_outflow[Medium.nC]Properties c_i/m close to the connection point if m_flow < 0

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