Recent experimental studies of evaporation in microchannels have shown that local flow-boiling coefficients are almost independent of vapor quality, weakly dependent on mass flux, moderately dependent on evaporating pressure, and strongly dependent on heat flux. In a conventional (macrochannel) geometry, such trends suggest nucleate boiling as the dominant heat transfer mechanism. In this paper, we put forward a simple new heat transfer model based on the hypothesis that thin-film evaporation into elongated bubbles is the important heat transfer mechanism in these flows. The new model predicts the above trends and quantitatively predicts flow-boiling coefficients for experimental data with several fluids. The success of this new model supports the idea that thin-film evaporation into elongated bubbles is the important heat transfer mechanism in microchannel evaporation. The model provides a new tool for the study of such flows, assists in understanding the heat transfer behavior, and provides a framework for predicting heat transfer.
Heat Transfer Model for Evaporation of Elongated Bubble Flows in Microchannels
Contributed by the Heat Transfer Division for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received by the Heat Transfer Division July 31, 2001; revision received August 13, 2002. Associate Editor: V. P. Carey.
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Jacobi, A. M., and Thome, J. R. (December 3, 2002). "Heat Transfer Model for Evaporation of Elongated Bubble Flows in Microchannels ." ASME. J. Heat Transfer. December 2002; 124(6): 1131–1136. https://doi.org/10.1115/1.1517274
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