Affiliation:
1. Applied Thermodynamics and Refrigeration, Royal Institute of Technology, KTH, SE100-44 Stockholm, Sweden
Abstract
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.
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science
Reference34 articles.
1. Evaporative Heat Transfer in Vertical Circular Microchannels;Owhaib;Appl. Therm. Eng.
2. Simultaneous Flow of Oil and Gas;Baker;Oil & Gas J.
3. A Flow Pattern Map for Glass-Liquid Flow in Horizontal Pipes;Mandhane;Int. J. Multiphase Flow
4. Hewitt, G. F., and Roberts, D. N., 1969, “Studies of Two-Phase Flow Patterns by Simultaneous X-Ray and Flash Photography,” Paper No. AERE-M 2159.
5. A Model for Predicting Flow Regime Transitions in Horizontal and Near Horizontal Gas-Liquid Flow;Taitel;AIChE J.
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