modelExample4

Example 4 model of simple condensing heat exchanger

Extends from Modelica.Icons.Example (Icon for runnable examples).

Information

This example generates a non-linear algebraic loop that consists of 12 equations before manipulation. This loop can be decoupled and removed by changing the equation

port_a.m_flow + port_b.m_flow = -mWat_flow;

in Annex60.Fluid.Interfaces.StaticTwoPortConservationEquation to

port_a.m_flow + port_b.m_flow = 0;

See Jorissen et al. (2015) for a discussion.

References

Filip Jorissen, Michael Wetter and Lieve Helsen.
Simulation speed analysis and improvements of Modelica models for building energy simulation.
Submitted: 11th Modelica Conference. Paris, France. Sep. 2015.

Parameters

Type	Name	Default	Description
Boolean	allowFlowReversal	false	= false to simplify equations, assuming, but not enforcing, no flow reversal

Components

Type	Name	Default	Description
Modelica.SIunits.MassFlowRate	m_condens	min(0, -vol.ports[1].m_flow*(bou.X[1] - xSat.X[1]))	Water vapor mass flow rate
Fluid.MixingVolumes.MixingVolumeMoistAir	vol		Mixing volume for extracting moisture
Fluid.HeatExchangers.ConstantEffectiveness	hex		Heat exchanger
Fluid.Sources.Boundary_pT	bou		Sink and source
Fluid.Sources.MassFlowSource_T	sou		Air source
Fluid.Sources.Boundary_pT	sin		Air sink
Modelica.Blocks.Sources.RealExpression	mCond
Annex60.Utilities.Psychrometrics.X_pTphi	xSat		Block for converting relative humidity into absolute humidity
Modelica.Blocks.Sources.Constant	phiSat		Humidity of 100%
Modelica.Blocks.Sources.Ramp	Tin		Inlet temperature ramp
FixedResistances.PressureDrop	res		Pressure drop component
Fluid.Sensors.TemperatureTwoPort	senTem		Temperature sensor

Name	Description
Medium

Revisions

July 28, 2015, by Michael Wetter:
Moved assignment of m_condens from equation section to declaration to avoid graphical and textual equations.
July 14, 2015, by Michael Wetter:
Revised documentation.
April 17, 2015, by Filip Jorissen:
First implementation.