BuildingSystems.Fluid.Interfaces.TwoPortHeatMassExchanger

# .BuildingSystems.Fluid.Interfaces.TwoPortHeatMassExchanger

Partial model transporting one fluid stream with storing mass or energy

## Information

This component transports one fluid stream. It provides the basic model for implementing dynamic and steady-state models that exchange heat and water vapor with the fluid stream. The model also computes the pressure drop due to the flow resistance. By setting the parameter `dp_nominal=0`, the computation of the pressure drop can be avoided. The variable `vol.heatPort.T` always has the value of the temperature of the medium that leaves the component. For the actual temperatures at the port, the variables `sta_a.T` and `sta_b.T` can be used. These two variables are provided by the base class BuildingSystems.Fluid.Interfaces.PartialTwoPortInterface.

For models that extend this model, see for example

- the ideal heater or cooler BuildingSystems.Fluid.HeatExchangers.HeaterCooler_u, and
- the ideal humidifier BuildingSystems.Fluid.Humidifiers.Humidifier_u.

#### Implementation

The variable names follow the conventions used in Modelica.Fluid.Examples.HeatExchanger.BaseClasses.BasicHX .

## Revisions

- March 3, 2022, by Michael Wetter:
  Removed `massDynamics`.
  This is for issue 1542.
- April 14, 2020, by Michael Wetter:
  Changed `homotopyInitialization` to a constant.
  This is for IBPSA, #1341.
- December 1, 2016, by Michael Wetter:
  Updated model as `use_dh` is no longer a parameter in the pressure drop model.
  This is for #480.
- January 26, 2016, by Michael Wetter:
  Added `final quantity=Medium.substanceNames` for `X_start`.
- May 6, 2015, by Michael Wetter:
  Added missing propagation of `allowFlowReversal` to instance `vol`. This is for issue #412.
- May 1, 2015, by Marcus Fuchs:
  Fixed links in documentation.
- October 6, 2014, by Michael Wetter:
  Changed medium declaration in pressure drop element to be final.
- May 28, 2014, by Michael Wetter:
  Removed `annotation(Evaluate=true)` for parameter `tau`. This is needed to allow changing the time constant after translation.
- November 12, 2013, by Michael Wetter:
  Removed `import Modelica.Constants` statement.
- October 8, 2013, by Michael Wetter:
  Removed parameter `show_V_flow`.
- December 14, 2012 by Michael Wetter:
  Renamed protected parameters for consistency with the naming conventions.
- October 17, 2012, by Michael Wetter:
  Fixed broken link in documentation.
- February 3, 2012, by Michael Wetter:
  Removed assignment of `m_flow_small` as it is no longer used in the pressure drop model.
- January 15, 2011, by Michael Wetter:
  Fixed wrong class reference in information section.
- September 13, 2011, by Michael Wetter:
  Changed assignment of `vol(mass/energyDynamics=...)` as the previous assignment caused a non-literal start value that was ignored.
- July 29, 2011, by Michael Wetter:
  Added start value for outflowing enthalpy.
- July 11, 2011, by Michael Wetter:
  Changed parameterization of fluid volume so that steady-state balance is used when `tau = 0`.
- May 25, 2011, by Michael Wetter:
  Removed temperature sensor and changed implementation of fluid volume to allow use of this model for the steady-state and dynamic humidifier BuildingSystems.Fluid.MassExchangers.HumidifierPrescribed.
- March 25, 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.
- April 13, 2009, by Michael Wetter:
  Added model to compute flow friction.
- January 29, 2009 by Michael Wetter:
  First implementation.

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