October 7, 2024 Dataset Restricted Access

Singh, Digvijay; Boden, Stephan; Schlegel, Fabian

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{
  "language": "eng", 
  "id": "4025", 
  "version": "5.0.0", 
  "title": "FVV1455: CFD Simulation of Droplet Separators", 
  "author": [
    {
      "family": "Singh, Digvijay"
    }, 
    {
      "family": "Boden, Stephan"
    }, 
    {
      "family": "Schlegel, Fabian"
    }
  ], 
  "issued": {
    "date-parts": [
      [
        2024, 
        10, 
        7
      ]
    ]
  }, 
  "publisher": "Rodare", 
  "DOI": "10.14278/rodare.4025", 
  "note": "The research project was self-financed (FVV funding no. 1455) by the FVV e.V.", 
  "type": "dataset", 
  "abstract": "<p>For industrial applications, the two-fluid model is preferred due to its&nbsp;<br>\nefficient modelling of small-scale interfaces. Whereas, a thin film model,&nbsp;<br>\nbased on a long wave approximation, is used for the unresolved interfaces to&nbsp;<br>\nobtain the film features by solving the 2D Navier-Stokes equations for wall&nbsp;<br>\nfilms. Within the project, the target is to develop an experimentally validated&nbsp;<br>\n3D-CFD model to investigate the separation efficiency of droplet separators for&nbsp;<br>\nfuel cell systems. A hybrid model is developed, which couples the two-fluid&nbsp;<br>\nmodel with a thin film model via mass transfer terms for droplet deposition,&nbsp;<br>\ndroplet entrainment and film separation. A two-way coupling between droplets&nbsp;<br>\nand the thin film is established using mass and momentum source terms, derived&nbsp;<br>\nanalytical and from available experiments. The droplet separator is an essential&nbsp;<br>\ncomponent of an automotive fuel cell system that segregates a significant amount&nbsp;<br>\nof liquid fractions from the air-water mixture. The flow dynamics inside a&nbsp;<br>\ndroplet separator consist of a dispersed gas and liquid with a wall adhered&nbsp;<br>\nthin liquid film. The modelling is divided into the following stages due to the&nbsp;<br>\ncomplex fluidic phenomenon inside a generic droplet separator:</p>\n\n<ul>\n\t<li>Droplet deposition model,</li>\n\t<li>Film separation model,</li>\n\t<li>Film transition model, and</li>\n\t<li>Population balance model.</li>\n</ul>\n\n<p>In order to systematically validate numerical models and methods that predict&nbsp;<br>\nthe characteristics of films and the separation efficiencies of droplet&nbsp;<br>\nseparators, high-quality experimental data must be carefully acquired. For the&nbsp;<br>\nexperimental investigations an air-water two-phase flow loop was set up. The&nbsp;<br>\nflow loop is extensively instrumented in order to provide precise data on the&nbsp;<br>\nrespective operating conditions such as mass low and pressure drop. The&nbsp;<br>\nfollowing advanced measurement techniques have been applied:</p>\n\n<ul>\n\t<li>HZDR&#39;s flow microscope to investigate droplet flow,</li>\n\t<li>HZDR&#39;s advanced microfocus X-ray tomograph to visualize the liquid films, and</li>\n\t<li>radioscopic imaging to investigate dynamic flow processes.</li>\n</ul>\n\n<p>The generic droplet separator was extensively tested under varying operating&nbsp;<br>\nconditions at a total of 27 measurement points covering a wide range of mostly&nbsp;<br>\nwavy and annular inlet flow conditions. The resulting comprehensive set of&nbsp;<br>\nexperimental data provides an excellent basis for the development and validation<br>\nof numerical design tools required by the industry.</p>"
}