Modelica.Fluid.Vessels.BaseClasses

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

Information

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

Package Content

Name Description
Modelica.Fluid.Vessels.BaseClasses.PartialLumpedVessel PartialLumpedVessel Lumped volume with a vector of fluid ports and replaceable heat transfer model
Modelica.Fluid.Vessels.BaseClasses.HeatTransfer HeatTransfer HeatTransfer models for vessels
Modelica.Fluid.Vessels.BaseClasses.VesselPortsData 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
Modelica.Fluid.Vessels.BaseClasses.VesselFluidPorts_a VesselFluidPorts_a Fluid connector with filled, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging)
Modelica.Fluid.Vessels.BaseClasses.VesselFluidPorts_b VesselFluidPorts_b Fluid connector with outlined, large icon to be used for horizontally aligned vectors of FluidPorts (vector dimensions must be added after dragging)

Modelica.Fluid.Vessels.BaseClasses.PartialLumpedVessel 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

NameDescription
replaceable package MediumMedium 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
energyDynamicsFormulation of energy balance
massDynamicsFormulation of mass balance
Heat transfer
use_HeatTransfer= true to use the HeatTransfer model
replaceable model HeatTransferWall heat transfer
Initialization
p_startStart value of pressure [Pa]
use_T_start= true, use T_start, otherwise h_start
T_startStart value of temperature [K]
h_startStart 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_nominalNominal value for mass flow rates in ports [kg/s]
m_flow_smallRegularization range at zero mass flow rate [kg/s]
use_Re= true, if turbulent region is defined by Re, otherwise by m_flow_small

Connectors

NameDescription
ports[nPorts]Fluid inlets and outlets
heatPort 
Assumptions
Heat transfer
replaceable model HeatTransferWall heat transfer

Modelica.Fluid.Vessels.BaseClasses.VesselPortsData 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).

Parameters

NameDescription
diameterInner (hydraulic) diameter of inlet/outlet port [m]
heightHeight over the bottom of the vessel [m]
zeta_outHydraulic resistance out of vessel, default 0.5 for small diameter mounted flush with the wall
zeta_inHydraulic resistance into vessel, default 1.04 for small diameter mounted flush with the wall

Modelica.Fluid.Vessels.BaseClasses.VesselFluidPorts_a 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)

Information

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)).

Parameters

NameDescription
replaceable package MediumMedium model

Contents

NameDescription
m_flowMass flow rate from the connection point into the component [kg/s]
pThermodynamic pressure in the connection point [Pa]
h_outflowSpecific 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

Modelica.Fluid.Vessels.BaseClasses.VesselFluidPorts_b 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)

Information

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)).

Parameters

NameDescription
replaceable package MediumMedium model

Contents

NameDescription
m_flowMass flow rate from the connection point into the component [kg/s]
pThermodynamic pressure in the connection point [Pa]
h_outflowSpecific 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
Automatically generated Tue Apr 05 09:36:46 2016.