CharLine L4
Created Donnerstag 15 Oktober 2015
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 L4 according to Brunnemann et al. [1] because the system is modelled with the use of balance equations, which are spatially averaged over the component..
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 L3
5. Nomenclature
6. Governing Equations
The mean temperature difference is defined as follows, based on the user's choice in the boolean parameter temperatureDifference:
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
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
- 2012 - v 0.1 - initial implementation - Friedrich Gottelt, XRG Simulation
- 2016 - v 1.1 - introduced logarithmic temperature difference option - Timm Hoppe, XRG Simulation
Backlinks: ClaRa:Components:HeatExchangers:FlatTubeFinnedHEXvle2gas L4 ClaRa:Basics:ControlVolumes:FluidVolumes:VolumeVLE L4 Advanced ClaRa:Basics:ControlVolumes:Fundamentals:HeatTransport:VLE HT:NusseltPipe L4