CharLine L2

Created Wednesday 05 June 2013

A heat transfer model based on the mean heat transfer coefficient (htc) which is a piece-wise linear function of mass flow rate and a nominal value

1. Purpose of Model

This model allows a flexible definition of the heat transfer coefficient depending on the mass flow rate. The model is appropriate when dependencies of the fluid properties on the heat transfer are negligible. The part load behavior of the htc is defined via a characteristic table. Since the evaluation of this table is piece-wise linear, the model is fairly robust but the function's derivative is not continuous which introduces events.

2. Physical Insight

This replaceable model is compatible to models of level of detail L2 according to Brunnemann et al. [1] since no spacial resolution of the heat transfer is assumed.

3. Limits of Validity

no dependencies of fluid properties, e.g. from density or Prandtl - number
accuracy may vary significantly depending on the chosen value for the parameter temperatureDifference

4. Interfaces

The model communicates via outer models and records. Thus its expects to have:

an outer model named geo as defined Fundamentals:Geometry:GenericGeometry
an outer record named iCom as defined in Basics:Records:IComBase L2

It has further a Basics:Interfaces:HeatPort a heat that shall be connected with the applying component model.

5. Nomenclature

6. Governing Equations

The mean temperature difference is defined as follows, based on the user's choice in the boolean parameter temperature difference:

Please note that for the choice temperatureDifference="Logarithmic mean" a number of means is applied to make the equation regular also for zero heat flow and reversing heat flows. If an unsupported string for temperatureDifference is provided an assert would raise.

The heat transfer coefficient α will be calculated as follows:

In the above equation we have

7. Remarks for Usage

Avoid very large values for as it will cause numerical problems without gaining extra precision. Use IdealHeatTransfer L2 instead.

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 Simulationof 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

2012 - v 0.1 - initial implementation - Friedrich Gottelt, XRG Simulation