Heat transfer model for evaporation in microchannels. Part I: presentation of the model

• Published in: International journal of heat and mass transfer Vol. 47; no. 14; pp. 3375 - 3385
• Main Authors: Thome, J.R., Dupont, V., Jacobi, A.M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2004; Elsevier
• Subjects: Applied sciences; Devices using thermal energy; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Heat exchangers (included heat transformers, condensers, cooling towers); Dry out; Liquid film; Heat exchanger; Compact heat exchanger; Evaporation; Microchannel plates; Heat transfer coefficient; Layer thickness; Modeling; Heat transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2004.01.006

A three-zone flow boiling model is proposed to describe evaporation of elongated bubbles in microchannels. The heat transfer model describes the transient variation in local heat transfer coefficient during the sequential and cyclic passage of (i) a liquid slug, (ii) an evaporating elongated bubble and (iii) a vapor slug. A time-averaged local heat transfer coefficient is thus obtained. The new model illustrates the importance of the strong cyclic variation in the heat transfer coefficient and the strong dependency of heat transfer on the bubble frequency, the minimum liquid film thickness at dryout and the liquid film formation thickness.