Confocal Microscopy for Capillary Film Measurements in a Flat Plate Heat Pipe
This paper aims to show how confocal microscopy can be useful for characterizing menisci in a flat plate heat pipe made of silicon. The capillary structure is made of radial microgrooves whose width d...
This paper aims to show how confocal microscopy can be useful for characterizing menisci in a flat plate heat pipe made of silicon. The capillary structure is made of radial microgrooves whose width d...
Convection Calibration of Schmidt–Boelter Heat Flux Gauges in Stagnation and Shear Air Flow
Experiments were performed to characterize the performance of Schmidt–Boelter heat flux gauges in stagnation and shear convective air flows. The gauges were of a standard design (25.4 mm and 38 ...
Experiments were performed to characterize the performance of Schmidt–Boelter heat flux gauges in stagnation and shear convective air flows. The gauges were of a standard design (25.4 mm and 38 ...
Flow Boiling Visualization of R-134a in a Vertical Channel of Small Diameter
J. Heat Transfer -- March 2010 -- Volume 132, Issue 3, 031503 (8 pages)
doi:10.1115/1.4000012
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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.
©2010 American Society of Mechanical Engineers
| History: | Received 13 February 2008; revised 1 September 2008; published 7 January 2010 | |
| doi: | http://dx.doi.org/10.1115/1.4000012 | |
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