Monday August 26, 2019 from 13:40 to 15:00
Modified flow pattern maps for flow boiling in horizontal micro-finned tubes considering the effect of helix angle
Cheng-Min Yang1, Pega Hrnjak1,2.
1University of Illinois at Urbana-Champaign/ ACRC, Urbana, United States; 2Creative Thermal Solutions, Urbana, United States
The existed flow pattern map of flow boiling are mainly developed for horizontal smooth tubes, which are not suitable for predicting the flow patterns in micro-finned tubes.
This paper presents an improved flow pattern map for flow boiling in horizontal micro-finned tubes considering the effect of helix angle.
Visualization of R410A flow boiling was carried out through the transparent smooth and micro-finned tubes with 0°, 10° and 18° helix angle.
The result shows that the flow pattern map for micro-finned tube with 0° helix angle is generally similar to that in the smooth tube. For the tube with 10° and 18° helix angle, the annular flow occurs at lower vapor quality and lower mass flux. A modified model accounting for the early transition to annular flow in the micro-finned tubes is built.