Modelica.Fluid.Interfaces

Information

Package Content

Name	Description
FluidPort	Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)
FluidPort_a	Generic fluid connector at design inlet
FluidPort_b	Generic fluid connector at design outlet
FluidPorts_a	Fluid connector with filled, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)
FluidPorts_b	Fluid connector with outlined, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)
PartialTwoPort	Partial component with two ports
PartialTwoPortTransport	Partial element transporting fluid between two ports without storage of mass or energy
HeatPorts_a	HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)
HeatPorts_b	HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)
PartialHeatTransfer	Common interface for heat transfer models
PartialLumpedVolume	Lumped volume with mass and energy balance
PartialLumpedFlow	Base class for a lumped momentum balance
PartialDistributedVolume	Base class for distributed volume models
PartialDistributedFlow	Base class for a distributed momentum balance
PartialPressureLoss	Base flow model for pressure loss functions with the same area at port_a and at port_b

Modelica.Fluid.Interfaces.FluidPort

Parameters

Name	Description
replaceable package Medium	Medium model

Contents

Name	Description
replaceable package Medium	Medium model
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

Modelica.Fluid.Interfaces.FluidPort_a

Information

Parameters

Name	Description
replaceable package Medium	Medium model

Contents

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

Modelica.Fluid.Interfaces.FluidPort_b

Information

Parameters

Name	Description
replaceable package Medium	Medium model

Contents

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

Modelica.Fluid.Interfaces.FluidPorts_a

Information

Parameters

Name	Description
replaceable package Medium	Medium model

Contents

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

Modelica.Fluid.Interfaces.FluidPorts_b

Information

Parameters

Name	Description
replaceable package Medium	Medium model

Contents

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

Modelica.Fluid.Interfaces.PartialTwoPort

Information

This partial model defines an interface for components with two ports. The treatment of the design flow direction and of flow reversal are predefined based on the parameter allowFlowReversal. The component may transport fluid and may have internal storage for a given fluid Medium.

An extending model providing direct access to internal storage of mass or energy through port_a or port_b should redefine the protected parameters port_a_exposesState and port_b_exposesState appropriately. This will be visualized at the port icons, in order to improve the understanding of fluid model diagrams.

Parameters

Name	Description
replaceable package Medium	Medium in the component
Assumptions
allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Name	Description
replaceable package Medium	Medium in the component
port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
port_b	Fluid connector b (positive design flow direction is from port_a to port_b)

Modelica.Fluid.Interfaces.PartialTwoPortTransport

Information

This component transports fluid between its two ports, without storing mass or energy. Energy may be exchanged with the environment though, e.g., in the form of work. PartialTwoPortTransport is intended as base class for devices like orifices, valves and simple fluid machines.

Three equations need to be added by an extending class using this component:

• the momentum balance specifying the relationship between the pressure drop dp and the mass flow rate m_flow,
• port_b.h_outflow for flow in design direction, and
• port_a.h_outflow for flow in reverse direction.

Moreover appropriate values shall be assigned to the following parameters:

• dp_start for a guess of the pressure drop
• m_flow_small for regularization of zero flow.

Parameters

Name	Description
replaceable package Medium	Medium in the component
Assumptions
allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
dp_start	Guess value of dp = port_a.p - port_b.p [Pa]
m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
m_flow_small	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
show_T	= true, if temperatures at port_a and port_b are computed
show_V_flow	= true, if volume flow rate at inflowing port is computed

Connectors

Name	Description
port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
port_b	Fluid connector b (positive design flow direction is from port_a to port_b)

Modelica.Fluid.Interfaces.HeatPorts_a

Information

Contents

Name	Description
T	Port temperature [K]
Q_flow	Heat flow rate (positive if flowing from outside into the component) [W]

Modelica.Fluid.Interfaces.HeatPorts_b

Information

Contents

Name	Description
T	Port temperature [K]
Q_flow	Heat flow rate (positive if flowing from outside into the component) [W]

Modelica.Fluid.Interfaces.PartialHeatTransfer

Information

This component is a common interface for heat transfer models. The heat flow rates Q_flows[n] through the boundaries of n flow segments are obtained as function of the thermodynamic states of the flow segments for a given fluid Medium, the surfaceAreas[n] and the boundary temperatures heatPorts[n].T.

The heat loss coefficient k can be used to model a thermal isolation between heatPorts.T and T_ambient.

An extending model implementing this interface needs to define one equation: the relation between the predefined fluid temperatures Ts[n], the boundary temperatures heatPorts[n].T, and the heat flow rates Q_flows[n].

Parameters

Name	Description
Ambient
k	Heat transfer coefficient to ambient [W/(m2.K)]
T_ambient	Ambient temperature [K]
Internal Interface
replaceable package Medium	Medium in the component
n	Number of heat transfer segments
use_k	= true to use k value for thermal isolation

Connectors

Name	Description
heatPorts[n]	Heat port to component boundary
Internal Interface
replaceable package Medium	Medium in the component

Modelica.Fluid.Interfaces.PartialLumpedVolume

Information

Interface and base class for an ideally mixed fluid volume with the ability to store mass and energy. The following boundary flow and source terms are part of the energy balance and must be specified in an extending class:

• Qb_flow, e.g., convective or latent heat flow rate across segment boundary, and
• Wb_flow, work term, e.g., p*der(fluidVolume) if the volume is not constant.

The component volume fluidVolume is an input that needs to be set in the extending class to complete the model.

Further source terms must be defined by an extending class for fluid flow across the segment boundary:

• Hb_flow, enthalpy flow,
• mb_flow, mass flow,
• mbXi_flow, substance mass flow, and
• mbC_flow, trace substance mass flow.

Parameters

Name	Description
replaceable package Medium	Medium in the component
Assumptions
Dynamics
energyDynamics	Formulation of energy balance
massDynamics	Formulation of mass balance
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

Connectors

Name	Description
replaceable package Medium	Medium in the component

Modelica.Fluid.Interfaces.PartialLumpedFlow

Information

Interface and base class for a momentum balance, defining the mass flow rate m_flow of a given Medium in a flow model.

The following boundary flow and force terms are part of the momentum balance and must be specified in an extending model (to zero if not considered):

• Ib_flow, the flow of momentum across model boundaries,
• F_p[m], pressure force, and
• F_fg[m], friction and gravity forces.

The length of the flow path pathLength is an input that needs to be set in an extending class to complete the model.

Parameters

Name	Description
replaceable package Medium	Medium in the component
Assumptions
allowFlowReversal	= true to allow flow reversal, false restricts to design direction (m_flow >= 0)
Dynamics
momentumDynamics	Formulation of momentum balance
Initialization
m_flow_start	Start value of mass flow rates [kg/s]

Connectors

Name	Description
replaceable package Medium	Medium in the component

Modelica.Fluid.Interfaces.PartialDistributedVolume

Information

Interface and base class for n ideally mixed fluid volumes with the ability to store mass and energy. It is intended to model a one-dimensional spatial discretization of fluid flow according to the finite volume method. The following boundary flow and source terms are part of the energy balance and must be specified in an extending class:

• Qb_flows[n], heat flow term, e.g., conductive heat flows across segment boundaries, and
• Wb_flows[n], work term.

The component volumes fluidVolumes[n] are an input that needs to be set in an extending class to complete the model.

Further source terms must be defined by an extending class for fluid flow across the segment boundary:

• Hb_flows[n], enthalpy flow,
• mb_flows[n], mass flow,
• mbXi_flows[n], substance mass flow, and
• mbC_flows[n], trace substance mass flow.

Parameters

Name	Description
replaceable package Medium	Medium in the component
n	Number of discrete volumes
Assumptions
Dynamics
energyDynamics	Formulation of energy balances
massDynamics	Formulation of mass balances
Initialization
p_a_start	Start value of pressure at port a [Pa]
p_b_start	Start value of pressure at port b [Pa]
use_T_start	Use T_start if true, 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

Connectors

Name	Description
replaceable package Medium	Medium in the component

Modelica.Fluid.Interfaces.PartialDistributedFlow

Information

Interface and base class for m momentum balances, defining the mass flow rates m_flows[m] of a given Medium in m flow segments.

The following boundary flow and force terms are part of the momentum balances and must be specified in an extending model (to zero if not considered):

• Ib_flows[m], the flows of momentum across segment boundaries,
• Fs_p[m], pressure forces, and
• Fs_fg[m], friction and gravity forces.

The lengths along the flow path pathLengths[m] are an input that needs to be set in an extending class to complete the model.

Parameters

Name	Description
replaceable package Medium	Medium in the component
m	Number of flow segments
Assumptions
allowFlowReversal	= true to allow flow reversal, false restricts to design direction (m_flows >= zeros(m))
Dynamics
momentumDynamics	Formulation of momentum balance
Initialization
m_flow_start	Start value of mass flow rates [kg/s]

Connectors

Name	Description
replaceable package Medium	Medium in the component

Modelica.Fluid.Interfaces.PartialPressureLoss

Information

Parameters

Name	Description
replaceable package Medium	Medium in the component
Assumptions
allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
dp_start	Guess value of dp = port_a.p - port_b.p [Pa]
m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
m_flow_small	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
show_T	= true, if temperatures at port_a and port_b are computed
show_V_flow	= true, if volume flow rate at inflowing port is computed

Connectors

Name	Description
port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
port_b	Fluid connector b (positive design flow direction is from port_a to port_b)