QuadraticNominalPoint L2

Created Friday 04 April 2014

A quadratic pressure drop model - depending of nominal values of pressure difference and mass flow rate and the square root of the actual pressure difference

1. Purpose of Model

This model is appropriate if a pressure drop due to friction, depending on the load is needed (either due to numerical or technical reasons). The model is parameterised by choosing a nominal load point and the corresponding pressure loss. The quadratic correlation is valid for turbulent flow in rough conduits. Thus, huge changes from nominal point can be calculated properly (as long as no change in flow regime occurs).

2. Physical Insight

This replaceable model is compatible to models of level of detail L2 according to Brunnemann et al. [1] since the friction losses are lumped over the component. The model is regularised around zero, to avoid numerical instability in that point.

3. Limits of Validity

no supercritical flow conditions are supported
no significant changes of inlet density over time
no changes in flow regime (to laminar or transitional flow regime)

4. Interfaces

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

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

5. Nomenclature

6. Governing Equations

is regularised for values below via Basics:Functions:ThermoRoot function

Eq. (1) and (2) can be reformulated to

The density is assumed to be the nominal density.

7. Remarks for Usage

The model should be used if huge changes in the load can be expected. The model bases on the quadratic correlation of mass flow rate to pressure loss. Thus, the accuracy in load points which differ significantly from the nominal point is better than in the LinearPressureLoss L2 model.
If changes in the density are expected the density dependent pressure loss model VLE PL:QuadraticNominalPoint L2 should be used.

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