Experimental study of post-dryout with R-134a upward flow in smooth tube and rifled tubes.
Author(s) : LEE S. K., CHANG S. H.
Type of article: Article
Summary
A study of post-dryout heat transfer was performed with a directed heated smooth tube and rifled tubes using vertical R-134a up-flow to investigate the heat transfer characteristics in the post-dryout region. Three types of rifled tube having different rib height and width were used to examine the effects of rib geometry and compare with the smooth tube, using a mass flux of 70-800 kg/m2.s and a pressure of 13-24 bars (corresponding to an approximate water pressure of 80-140 bars). Wall temperature distribution in all tubes was strongly dependent on pressure and mass flux. Wall temperatures of the rifled tubes in the post-dryout region were much lower than for the smooth tube at same conditions. This was attributed to swirl flow caused by the rib. Thus, the thermal non-equilibrium, which is usually present in the post-dryout region, was lowered. The empirical correlation of heat transfer in the smooth tube of the post-dryout region was obtained. The heat transfer correlation for rifled tubes was also obtained as a function of rib height and width with the modification of the smooth tube correlation. [Reprinted with permission from Elsevier. Copyright, 2007].
Details
- Original title: Experimental study of post-dryout with R-134a upward flow in smooth tube and rifled tubes.
- Record ID : 2008-2049
- Languages: English
- Source: International Journal of Heat and Mass Transfer - vol. 51 - n. 11-12
- Publication date: 2008/06
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Indexing
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Themes:
HFCs;
Heat transfer - Keywords: R134a; Vertical tube; Ribbed tube; Heat transfer; Bare pipe; Superheat; Expérimentation; Flow; Refrigerant
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