modelPartialFourPortInterface

Partial model with four ports and declaration of quantities that are used by many models
Diagram of PartialFourPortInterfaceOpen the diagram

Extends from Buildings.Fluid.Interfaces.PartialFourPort (Partial model with four ports).

Information

This component defines the interface for models with four fluid ports and two fluid streams. It is similar to Buildings.Fluid.Interfaces.PartialTwoPortInterface, but it has four ports instead of two.

The model is used by other models in this package that add heat transfer, mass transfer and pressure drop equations.

Parameters

TypeNameDefaultDescription
Assumptions
BooleanallowFlowReversal1 (from PartialFourPort)true= false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1
BooleanallowFlowReversal2 (from PartialFourPort)true= false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2
Nominal condition
Modelica.Units.SI.MassFlowRatem1_flow_nominalNominal mass flow rate
Modelica.Units.SI.MassFlowRatem2_flow_nominalNominal mass flow rate
Advanced
Medium1.MassFlowRatem1_flow_small1E-4*abs(m1_flow_nominal)Small mass flow rate for regularization of zero flow
Medium2.MassFlowRatem2_flow_small1E-4*abs(m2_flow_nominal)Small mass flow rate for regularization of zero flow
Advanced › Diagnostics
Booleanshow_Tfalse= true, if actual temperature at port is computed

Connectors

TypeNameDefaultDescription
Modelica.Fluid.Interfaces.FluidPort_aport_a1 (from PartialFourPort)Fluid connector a1 (positive design flow direction is from port_a1 to port_b1)
Modelica.Fluid.Interfaces.FluidPort_bport_b1 (from PartialFourPort)Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)
Modelica.Fluid.Interfaces.FluidPort_aport_a2 (from PartialFourPort)Fluid connector a2 (positive design flow direction is from port_a2 to port_b2)
Modelica.Fluid.Interfaces.FluidPort_bport_b2 (from PartialFourPort)Fluid connector b2 (positive design flow direction is from port_a2 to port_b2)

Components

TypeNameDefaultDescription
Medium1.MassFlowRatem1_flowport_a1.m_flowMass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction)
Modelica.Units.SI.PressureDifferencedp1port_a1.p - port_b1.pPressure difference between port_a1 and port_b1
Medium2.MassFlowRatem2_flowport_a2.m_flowMass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction)
Modelica.Units.SI.PressureDifferencedp2port_a2.p - port_b2.pPressure difference between port_a2 and port_b2
Medium1.ThermodynamicStatesta_a1if allowFlowReversal1 then Medium1.setState_phX(port_a1.p, noEvent(actualStream(port_a1.h_outflow)), noEvent(actualStream(port_a1.Xi_outflow))) else Medium1.setState_phX(port_a1.p, inStream(port_a1.h_outflow), inStream(port_a1.Xi_outflow))Medium properties in port_a1
Medium1.ThermodynamicStatesta_b1if allowFlowReversal1 then Medium1.setState_phX(port_b1.p, noEvent(actualStream(port_b1.h_outflow)), noEvent(actualStream(port_b1.Xi_outflow))) else Medium1.setState_phX(port_b1.p, port_b1.h_outflow, port_b1.Xi_outflow)Medium properties in port_b1
Medium2.ThermodynamicStatesta_a2if allowFlowReversal2 then Medium2.setState_phX(port_a2.p, noEvent(actualStream(port_a2.h_outflow)), noEvent(actualStream(port_a2.Xi_outflow))) else Medium2.setState_phX(port_a2.p, inStream(port_a2.h_outflow), inStream(port_a2.Xi_outflow))Medium properties in port_a2
Medium2.ThermodynamicStatesta_b2if allowFlowReversal2 then Medium2.setState_phX(port_b2.p, noEvent(actualStream(port_b2.h_outflow)), noEvent(actualStream(port_b2.Xi_outflow))) else Medium2.setState_phX(port_b2.p, port_b2.h_outflow, port_b2.Xi_outflow)Medium properties in port_b2

Revisions

  • September 22, 2023, by Michael Wetter:
    Improved documentation.
    This is for IBPSA, #1796.
  • February 3, 2022, by Michael Wetter:
    If allowFlowReversal==false, removed noEvent() declaration for sta_a and for sta_b because the variable is either already used with inStream() in the computation of state_*_inflow, or the result of a variable of the model that already may generate an event.
    This is for IBPSA, #1578.
  • February 2, 2022, by Hongxiang Fu:
    If allowFlowReversal==false, replaced actualStream() with inStream() for sta_a and removed actualStream() for sta_b.
    This is for IBPSA, #1578.
  • March 30, 2021, by Michael Wetter:
    Added annotation HideResult=true.
    This is for IBPSA, #1459.
  • November 3, 2016, by Michael Wetter:
    Moved computation of pressure drop to variable assignment so that the model won't mix graphical with textual modeling if used as a base class for a graphically implemented model.
  • November 3, 2016, by Michael Wetter:
    Removed start values for mass flow rate and pressure difference to simplify the parameter window.
    This is for #552.
  • January 22, 2016, by Michael Wetter:
    Corrected type declaration of pressure difference. This is for #404.
  • November 13, 2013 by Michael Wetter:
    Removed assignment of min and max attributes of port mass flow rates, as this is already done in the base class.
  • November 12, 2013 by Michael Wetter:
    Removed import Modelica.Constants; statement.
  • November 11, 2013 by Michael Wetter:
    Removed the parameter homotopyInitialization as it is no longer used in this model.
  • November 10, 2013 by Michael Wetter:
    In the computation of sta_a1, sta_a2, sta_b1 and sta_b2, removed the branch that uses the homotopy operator. The rational is that these variables are conditionally enables (because of ... if show_T). Therefore, the Modelica Language Specification does not allow for these variables to be used in any equation. Hence, the use of the homotopy operator is not needed here.
  • October 10, 2013 by Michael Wetter:
    Added noEvent to the computation of the states at the port. This is correct, because the states are only used for reporting, but not to compute any other variable. Use of the states to compute other variables would violate the Modelica language, as conditionally removed variables must not be used in any equation.
  • October 8, 2013 by Michael Wetter:
    Removed the computation of V_flow and removed the parameter show_V_flow. The reason is that the computation of V_flow required the use of sta_a (to compute the density), but sta_a is also a variable that is conditionally enabled. However, this was not correct Modelica syntax as conditional variables can only be used in a connect statement, not in an assignment. Dymola 2014 FD01 beta3 is checking for this incorrect syntax. Hence, V_flow was removed as its conditional implementation would require a rather cumbersome implementation that uses a new connector that carries the state of the medium.
  • April 26, 2013 by Marco Bonvini:
    Moved the definitions of dp1 and dp2 because they cause some problem with PyFMI.
  • March 27, 2012 by Michael Wetter:
    Replaced the erroneous function call Medium.density with Medium1.density and Medium2.density. Changed condition to remove sta_a1 and sta_a2 to also compute the states at the inlet port if show_V_flow=true. The previous implementation resulted in a translation error if show_V_flow=true, but worked correctly otherwise because the erroneous function call is removed if show_V_flow=false.
  • March 27, 2011 by Michael Wetter:
    Added homotopy operator.
  • March 21, 2010 by Michael Wetter:
    Changed pressure start value from system.p_start to Medium.p_default since HVAC models may have water and air, which are typically at different pressures.
  • September 19, 2008 by Michael Wetter:
    Added equations for the mass balance of extra species flow, i.e., C and mC_flow.
  • April 28, 2008, by Michael Wetter:
    First implementation.