Flow boiling visualization in a vertical circular minichannel at high vapor quality
2006 (English)In: Experimental Thermal and Fluid Science, ISSN 0894-1777, Vol. 30, no 8, 755-763 p.Article in journal (Refereed) Published
This paper reports on an experimental study of saturated flow boiling of R134a inside a circular vertical quartz tube coated with a transparent heater. The inner diameter of the tube was 1.33 mm and the heated length 235.5 mm. The flow pattern at high vapor qualities and the dryout of the liquid film were studied using a high speed CCD camera at the mass fluxes 47.4 and 124.4 kg/m(2) s in up flow at 6.425 bar. The heat fluxes ranged from 5 to 13.6 kW/m(2) for the lower mass flux and from 20 to 32.4 kW/m(2) for the higher mass flux.
The behavior of the flow close to dryout was found to be different at low and high mass flux. At low mass flux the location of the liquid front fluctuated with waves passing high up in the tube. In between the waves, a thin film was formed, slowly evaporating without breaking up.
At high mass flux the location of the liquid front was more stable. In this case the liquid film was seen to break up into liquid streams and dry zones on the tube wall.
Place, publisher, year, edition, pages
2006. Vol. 30, no 8, 755-763 p.
Dryout; Flow boiling; Minichannel; Visualization; Charge coupled devices; Evaporation; Flow visualization; Thin films; Vapors; Dryout; Flow boiling; Mass flux; Minichannels; Pipe flow; Charge coupled devices; Evaporation; Flow visualization; Pipe flow; Thin films; Vapors
IdentifiersURN: urn:nbn:se:kth:diva-6867DOI: 10.1016/j.expthermflusci.2006.03.005ISI: 000241181700006ScopusID: 2-s2.0-33746459316OAI: oai:DiVA.org:kth-6867DiVA: diva2:11697
QC 20100812. Konferens: International Conference on Heat Transfer and Fluid Flow in Microscale, Barga, Italy, Sep 25-30, 2005. ENEA, Inst Thermal Fluid Dynam.2007-03-092007-03-092011-09-27Bibliographically approved