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Flow pattern transition instability during flow boiling in a single microchannel.

Author(s) : HUH C., KIM J., KIM M. H.

Type of article: Article

Summary

The authors studied the unique characteristics of flow boiling in a single microchannel, including the periodic pressure drop, mass flow rate, and temperature fluctuations, in terms of a long time period. Experiments were conducted using a single horizontal microchannel and deionized water to study boiling instabilities at very small mass and heat flow rate conditions. A polydimethylsiloxane (PDMS) rectangular single microchannel had a hydraulic diameter of 103.5 micro-m and a length of 40 mm. A series of piecewise serpentine platinum microheaters were fabricated on the inner bottom wall of the rectangular microchannel to supply thermal energy to the test fluid. Real-time flow visualizations of the flow pattern inside the microchannel were performed simultaneously with measurements of the experimental parameters. Tests were performed for mass fluxes of 170 and 360 kg/m2.s and heat fluxes of 200-530 kW/m2. The test results showed that the heated wall temperature, pressure drop, and mass flux all fluctuated with a long period and large amplitude. These periodic fluctuations exactly matched the transition of two alternating flow patterns inside the microchannel: a bubbly/slug flow and an elongated slug/semi-annular flow. Therefore, the flow pattern transition instability in the single microchannel caused a cyclic behavior of the wall temperature, pressure drop, and mass flux, and this behavior had a very long period (100-200 s) and large amplitude. [Reprinted with permission from Elsevier. Copyright, 2006].

Details

  • Original title: Flow pattern transition instability during flow boiling in a single microchannel.
  • Record ID : 2007-1466
  • Languages: English
  • Source: International Journal of Heat and Mass Transfer - vol. 50 - n. 5-6
  • Publication date: 2007/03

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