NusseltPipe L4
Created Mittwoch 21 Oktober 2015
Heat transfer model based on Nusselt Number for one-phase pipe flow. Takes Geometry data, flow data and media data into account
1. Purpose of Model
A detailed model that takes all relevant dependencies into account. This model is numerically less robust than other models, e.g. HeatTransport:Generic HT:CharLine L4 since it takes fluid states and flow regimes into account. Phase change is not supported and will lead to unphysical heat transfer coefficients. Two correlations can be chosen. The Gnielinski correlation which takes surfaces roughness into account and the Dittus/Boelter correlation which assumes technical smooth pipes.
2. Level of Detail and Physical Effects Considered
2.1 Level of Detail
Referring to Brunnemann et al. [1], this model refers to the level of detail L4 because the system is modelled with the use of balance equations, which are spatially averaged over the component.
2.2 Physical Effects Considered
- dependencies of the heat transfer coefficient on the Reynolds Number
- dependencies of the heat transfer coefficient on the Prandtl Number
- reverse flow
- flow regime change
3. Limits of Validity
- simplified transition regime
- no two phase flow supported
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
5. Nomenclature
6. Governing Equations
The local heat transfer coefficients according to [2] for the laminar and the turbulent regime are calculated as follows:
with
A smooth transtion between 
of laminar and turbulent heat transfer coefficient is applied. The heat flow rate is calculated as follows:
7. Remarks for Usage
- If the computing efford has to be reduced or the model can be made responsible for numerical unstable behavior, use this model to tune e.g. HeatTransport:Generic HT:CharLine L4 and replace it.
- Check the results for meaningfulness, if the
is equal to 1, as the boundary conditions or valid ranges of the models are violated.
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
[2] Verein Deutscher Ingenieure: "VDI Heat Atlas", chapter Ga: 'Heat transfer in pipes' (in German), 9th edition, Springer 2002
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 - Ala Renz, Friedrich Gottelt, XRG-Simulation
- 2019 - v 1.4.0 - Local htc are calculated instead of mean htc with cell length, added homotopy init - Timm Hoppe, XRG-Simulation
Backlinks: ClaRa:Components:HeatExchangers:FlatTubeFinnedHEXvle2gas L4 ClaRa:Basics:ControlVolumes:FluidVolumes:VolumeVLE L4 Advanced