HEXvle2vle L3 1ph kA

Created Friday 01 November 2013

A general geometry desuperheater model with NTU-based heat transfer model applying a characteristic line for the product of k*A.

1. Purpose of Model


This model is well suited to model slow transients of commonly designed heat exchangers. If large-scale short-term transients occur, e.g. as can be found during start-up the model might give imprecise results since the basic assumptions of the NTU approach (applied for calculation of heat resistance) can be violated. Instead of calculating the heat exchanger performance from the heat transfer coefficients the performance is defined by a characteristic line for kA.
The geometry of the heat exchanger is mainly defined by the parameter heatExchangerType. With that parameter the principal flow situation is defined.

2. Level of Detail, Physical Effects Considered and Physical Insight


2.1 Level of Detail

Referring to Brunnemann et al. [1], this model refers to the level of detail L3 because the system is modelled with the use of balance equations applied to two different zones of the component: liquid condensate at tube side, vapour volume at shell side.

2.2 Physical Effects Considered

2.3 Level of Insight


Heat Transfer


shell side

Basics:ControlVolumes:Fundamentals:HeatTransport:Generic HT:Heat Transfer L2 : ideal heat transfer, i.e. kc is infinite (see also the remarks for usage)

tube side:

Basics:ControlVolumes:Fundamentals:HeatTransport:Generic HT:Heat Transfer L2 :ideal heat transfer, i.e. kc is infinite (see also the remarks for usage)

Pressure Loss


shell side


tubes side



Phase Separation


shell side

Basics:ControlVolumes:Fundamentals:SpatialDistributionAspects:IdeallyStirred : ideally mixed phases, no phase separation

tube side:

Basics:ControlVolumes:Fundamentals:SpatialDistributionAspects:IdeallyStirred : ideally mixed phases

Heat Exchanger Type


3. Limits of Validity

4. Interfaces


5. Nomenclature

- no model specific nomenclature -

6. Governing Equations


6.1 System Description and General model approach

This model is composed by instantiation of the following classes:

6.2 General Model Equations


Summary

A record summarising the most important variables is provided. Please be aware of the Boolean showExpertSummary in the parameter dialog tab "Summary and Visualisation". Setting this parameter to true will give you more detailed information on the components behaviour. The summary consists of the outline:

and the summaries of the class instances named in section 6.1

7. Remarks for Usage

The heat transfer is defined by a nominal kA and a mass flow dependent characteristic line instead of setting solid material and heat exchange models on shell and tube side.

7.1 Naming

The naming of heat exchangers in this package follows some specific form that is defined as follows:


7.2 Phase Change

Since the model has only one state on the tube side and the shell side respectively phase change is in principally possible but will result in low accuracy during the phase change transients. Furthermore, phase separation is not supported. To model phase change and separation on the shell side consider one of the two phase heat exchangers.


8. Validation


9. References

[1] Johannes Brunnemann and Friedrich Gottelt, Kai Wellner, Ala Renz, André Thüring, Volker Röder, Christoph Hasenbein, Christian Schulze, Gerhard Schmitz, Jörg Eiden: "Status of ClaRaCCS: Modelling and Simulation of Coal-Fired Power Plants with CO2 capture", 9th Modelica Conference, Munich, Germany, 2012

10. Authorship and Copyright Statement for original (initial) Contribution

Author:
DYNCAP/DYNSTART development team, Copyright 2011 - 2022.
Remarks:
This component was developed during DYNCAP/DYNSTART projects.
Acknowledgements:
ClaRa originated from the collaborative research projects DYNCAP and DYNSTART. Both research projects were supported by the German Federal Ministry for Economic Affairs and Energy (FKZ 03ET2009 and FKZ 03ET7060).
CLA:
The author(s) have agreed to ClaRa CLA, version 1.0. See https://claralib.com/pdf/CLA.pdf
By agreeing to ClaRa CLA, version 1.0 the author has granted the ClaRa development team a permanent right to use and modify his initial contribution as well as to publish it or its modified versions under the 3-clause BSD License.

11. Version History

- introduced option to define limiting HEX side (tube side is default) and tidied up parameter dialog - T.Hoppe, F.Gottelt, XRG Simulation