Modelica.Fluid.Vessels

Information

Package Content

Name	Description
ClosedVolume	Volume of fixed size, closed to the ambient, with inlet/outlet ports
OpenTank	Simple tank with inlet/outlet ports
BaseClasses	Base classes used in the Vessels package (only of interest to build new component models)

Modelica.Fluid.Vessels.ClosedVolume

Information

Ideally mixed volume of constant size with two fluid ports and one medium model. The flow properties are computed from the upstream quantities, pressures are equal in both nodes and the medium model if use_portsData=false. Heat transfer through a thermal port is possible, it equals zero if the port remains unconnected. A spherical shape is assumed for the heat transfer area, with V=4/3*pi*r^3, A=4*pi*r^2. Ideal heat transfer is assumed per default; the thermal port temperature is equal to the medium temperature.

If use_portsData=true, the port pressures represent the pressures just after the outlet (or just before the inlet) in the attached pipe. The hydraulic resistances portsData.zeta_in and portsData.zeta_out determine the dissipative pressure drop between volume and port depending on the direction of mass flow. See VesselPortsData and [Idelchik, Handbook of Hydraulic Resistance, 2004].

Parameters

Name	Description
replaceable package Medium	Medium in the component
fluidVolume	Volume [m3]
V	Volume [m3]
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

Connectors

Name	Description
ports[nPorts]	Fluid inlets and outlets
heatPort

Modelica.Fluid.Vessels.OpenTank

Information

Model of a tank that is open to the ambient at the fixed pressure p_ambient.

The vector of connectors ports represents fluid ports at configurable heights, relative to the bottom of tank. Fluid can flow either out of or in to each port.

• The tank is filled with a single or multiple-substance medium having a density higher than the density of the ambient medium.
• The fluid has uniform density, temperature and mass fractions
• No liquid is leaving the tank through the open top; the simulation breaks with an assertion if the liquid level growths over the height.

The port pressures represent the pressures just after the outlet (or just before the inlet) in the attached pipe. The hydraulic resistances portsData.zeta_in and portsData.zeta_out determine the dissipative pressure drop between tank and port depending on the direction of mass flow. See VesselPortsData and [Idelchik, Handbook of Hydraulic Resistance, 2004].

With the setting use_portsData=false, the port pressure represents the static head at the height of the respective port. The relationship between pressure drop and mass flow rate at the port must then be provided by connected components; Heights of ports as well as kinetic and potential energy of fluid entering or leaving are not taken into account anymore.

Parameters

Name	Description
height	Height of tank [m]
crossArea	Area of tank [m2]
replaceable package Medium	Medium in the component
fluidVolume	Volume [m3]
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
Ambient
p_ambient	Tank surface pressure [Pa]
T_ambient	Tank surface Temperature [K]
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
level_start	Start value of tank level [m]
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

Connectors

Name	Description
ports[nPorts]	Fluid inlets and outlets
heatPort