The present work reports on flow boiling visualization of refrigerant R-134a in a vertical circular channel with an internal diameter of 1.33 mm and 235 mm in heated length. A quartz tube with a homogeneous Indium Tin Oxide coating is used to allow heating and simultaneous visualization. Flow patterns have been observed along the heated length with the aid of high-speed complementary metal oxide semiconductor (CMOS) digital camera. From the flow boiling visualization, seven distinct two-phase flow patterns have been observed: isolated bubbly flow, confined bubbly flow, slug flow, churn flow, slug-annular flow, annular flow, and mist flow. Two-phase flow pattern observations are presented in the form of flow pattern maps. The effects of the saturation temperature and the inlet subcooling degree on the two-phase flow pattern transitions are elucidated. Finally, the experimental flow pattern map is compared with models developed for conventional sizes as well as to a microscale map for air-water mixtures available in literature, showing a large discrepancy.
Flow Boiling Visualization of R-134a in a Vertical Channel of Small Diameter
- Views Icon Views
- Share Icon Share
- Search Site
Martín-Callizo, C., Palm, B., Owhaib, W., and Ali, R. (January 7, 2010). "Flow Boiling Visualization of R-134a in a Vertical Channel of Small Diameter." ASME. J. Heat Transfer. March 2010; 132(3): 031503. https://doi.org/10.1115/1.4000012
Download citation file: