Advertisement

Interfacial and Plate Temperature Histories During Dropwise Condensation in the Presence of Noncondensibles

  • Frank Ganzevles
  • Cees van der Geld
Part of the Heat and Mass Transfer book series (HMT)

Abstract

Measurements with a thermograph, spectral range 2,0-5,6 (µm, reveal temperature gradients in liquid drops that condense from a gas mixture with noncondensibles present. They indicate the presence of Marangoni convection that may explain the finding that the average thermal resistance of the condensate in plastic compact heat exchangers is lower than the expected value based on pure conduction.

Histories of temperature fields of condenser plates exhibit, amongst other things, the importance of drainage by the large drops and the predicted linear decrease of the averaged interface temperature in the flow direction.

Dedicated experiments with an initially homogeneous binary drop show that Marangoni flow can also be driven by concentration gradients at the interface, sustained by refreshing from the bulk liquid. It is unclear whether this effect manifests itself in heat exchangers.

Keywords

Infrared photography dropwise condensation Marangoni convection 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Boer AWJP den, Geld CWM van der (1996) Thermocapillary convection in a liquid layer heated from above. Proc. of 2nd European Thermal-Science and 14th UIT National Heat Transfer ConferenceGoogle Scholar
  2. Brouwers HJH, Geld CWM van der (1996) Heat transfer, condensation and fog formation in crossflow plastic heat exchangers. Int. J. Heat Mass Transfer 39:391–405CrossRefGoogle Scholar
  3. Ganzevles FLA, Geld CWM van der (1997) The shape of conduction in a multiple channel slab and effect of non-uniform temperatures. Int. J. Heat Mass Transfer 40:2493–2498CrossRefGoogle Scholar
  4. Ganzevles FLA, Geld CWM van der (1998a) Marangoni convection in binary drops in air cooled from below. Int. J. Heat Mass Transfer 41:1293–1301CrossRefGoogle Scholar
  5. Ganzevles FLA, Geld CWM van der (1998b) Heat and mass transfer from internal flows to hemispheres and flat parts in between. Int. J. Heat Mass Transfer 41:3705–3718CrossRefGoogle Scholar
  6. Ganzevles FLA (1999, to appear) Drainage and condensate heat resistance in dropwise condensation of multicomponent mixtures in a plastic plate heat exchanger. Ph.D. Thesis, Eindhoven University of TechnologyGoogle Scholar
  7. Geld CWM, Ganzevles FLA (1993) Over de implementatie van het filmmodel en mistmodel (in Dutch). WOC-CMHT 2101.27. Eindhoven University of TechnologyGoogle Scholar
  8. Geld CWM van der, Brouwers HJH (1995) The mean condensate heat resistance of dropwise condensation with flowing, inert gases. Heat Mass Transfer 30: 435–445CrossRefGoogle Scholar
  9. Molenkamp T (1998) Marangoni convection, mass transfer and microgravity. Dissertation, Groningen UniversityGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Frank Ganzevles
    • 1
  • Cees van der Geld
    • 1
  1. 1.Faculty of Mechanical EngineeringEindhoven University of TechnologyMB EindhovenThe Netherlands

Personalised recommendations