RealMixed

Created Thursday 07 November 2013

Non-ideal mixing of the inlet mass flows

1. Purpose of Model

Typical applications of this replaceable model are:

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 L3 because it assumes an applying model of L3 featuring a fixed number (two) of distinct zones.

2.2 Physical Effects Considered


3. Limits of Validity

4. Interfaces


5. Nomenclature


6. Governing Equations

In general, it can be assumed that the non-ideal mixing process takes a certain time, depending on the mass and heat exchange between the phases, see figure below. These phenomena are taken into account in two-zonal control volumes with an arbitrary number of inlet and outlet ports. The task of the present model is to correlate the flow conditions at the ports with the two zones present in the model. This is also referred to as zone allocation which means that any incoming or outgoing mass flow has to be allocated to one of the two zones present in the model introducing the mass and enthalpy flows to the relevant energy and mass balances for the zones.
For a mixer the zone allocation of an outgoing mass flow depends on various parameters like component geometry, spray geometry, local velocities and many more. In order to handle this in a system simulation it is assumed that the mixture at the outlet port(s) correlates with the volume ratio in the component. Incoming mass flows are allocated to the zones according to the steam quality at the ports.

The mass flow leaving the component at the end of the mixing volume is allocated according to the volume ratio of the zones while entering mass flows are allocated according to its steam quality, i.e.

For illustration three examples are given below assuming a simple geometric setting.


For the sake of numerical robustness the Basics:Functions:Stepsmoother is applied to implement the above distinction of cases which leads to a principal behaviour as illustrated below.

Based on the zone allocation za the entering and leaving mass flows at the ports are allocated to the two zones by introducing zone related (or phase related) mass flow rates:

These zone-related mass flows are to be used in the applying model.

7. Remarks for Usage

To be combined with two-zonal control volumes with an arbitrary number of inlet and outlet ports. This model's energy and mass balances get access to the mass flow rates .

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


Backlinks: ClaRa:Basics:ControlVolumes:FluidVolumes:VolumeVLEGas L3 ClaRa:Basics:ControlVolumes:FluidVolumes:VolumeVLE L3 TwoZones ClaRa:Basics:ControlVolumes:FluidVolumes:VolumeVLE L3 TwoZonesNPort ClaRa:Components:VolumesValvesFittings:Fittings:JoinVLE L3 Y ClaRa:Components:VolumesValvesFittings:Fittings:SprayInjectorVLE L3 advanced