NusseltShell2ph L2
Created Thursday 13 June 2013
Heat transfer model based on Nusselt Number for single-phase and two-phase (condensation) shell flow around a tube bundle. Takes Geometry data, flow data and media data into account
1. Purpose of Model
A detailed model for shell geometries with a tube bundle, e.g. heat exchangers, that takes all relevant dependencies, including condensation, into account. This model is numerically less robust than other models, e.g HeatTransport:Generic HT:CharLine L2 since it takes fluid states and flow regimes into account.
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 L2 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 to the Reynolds Number
- dependencies of the heat transfer coefficient to the Prandtl Number
- reverse flow
- film condensation
3. Limits of Validity
- see FluidDissipation documentation for limits of the used equations
- no boiling, only film condensation
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
6.1 Calculation of one phase heat transfer coefficient
with the characteristic length calculated as follows:
The average Nusselt number for the whole tube bundle (for the 1 phase area) is calculated according to:
The one phase Nusselt number is calculated as follows:
with
and
and
and
6.2 Calculation of two phase heat transfer coefficient
with
The phase change number is calculated as follows:
The two phase Reynolds number is calculated as follows:
6.3 Calculation of heat flow rate
The heat transfer area can be changed with the integer parameter 
. The geometry record provides two areas, the lateral and the inner heat surface. 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.
7. Remarks for Usage
Check the results for meaningfulness, if the 
or 
are equal to 1, as the boundary conditions or valid ranges of the FluidDissipation models are violated.
8. Validation
see FluidDissipation documentation
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 - Ala Renz, Friedrich Gottelt, XRG-Simulation
- 2019 - v 1.4.0 - improved calculation of nominal values - Annika Kuhlmann, XRG-Simulation
Backlinks: ClaRa:Components:HeatExchangers:IdealShell L2 ClaRa:Basics:ControlVolumes:FluidVolumes:VolumeVLE L2