A comprehensive flow regime map for microchannel flow boiling with quantitative transition criteria

• Published in: International journal of heat and mass transfer Vol. 53; no. 13; pp. 2694 - 2702
• Main Authors: Harirchian, Tannaz, Garimella, Suresh V.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2010; Elsevier
• Subjects: Applied sciences; Boiling; Channels; Confinement; Confinement effects; Criteria; Cross sections; Cross-sectional area; Devices using thermal energy; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Flow regime map; Fluid dynamics; Fundamental areas of phenomenology (including applications); Heat exchangers (included heat transformers, condensers, cooling towers); Mass transfer; Microchannel flow boiling; Microchannel size; Microchannels; Multiphase and particle-laden flows; Nonhomogeneous flows; Physics; Transition criteria; Microchannel flow boiling; Microchannel size; Confinement effects; Cross-sectional area; Flow regime map; Transition criteria; Two phase flow; Flow regime; Pipe flow; Test facility; Microchannel; Experimental study; Microstructure; Heat sink; Heat transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2010.02.039

Due to the critical role of vapor confinement in establishing distinct flow and heat transfer characteristics in microchannels (as distinct from those in larger channels), the conditions under which such confinement occurs in microchannels are of great interest. It is shown in the present work that channel dimensions and flow properties alone, as proposed in past studies, are insufficient for determining confinement effects in microchannel boiling. Hence, a new criterion for physical confinement in microchannel flow boiling, termed the convective confinement number, that incorporates the effects of mass flux, as well as channel cross-sectional area and fluid properties, is proposed. This criterion helps determine the conditions under which a channel qualifies as a microchannel for two-phase flow, needing special treatment, and when a macroscale treatment is adequate. In addition, based on previous work by the authors, a new comprehensive flow regime map is developed for a wide range of experimental parameters and channel dimensions, along with quantitative transition criteria based on nondimensional boiling parameters.