000153618 001__ 153618
000153618 005__ 20190327210659.0
000153618 0247_ $$2doi$$a10.1016/j.expthermflusci.2010.08.004
000153618 022__ $$a0894-1777
000153618 02470 $$2ISI$$a000284968900005
000153618 037__ $$aARTICLE
000153618 245__ $$aMacro-to-microchannel transition in two-phase flow: Part 1 – Two-phase flow patterns and film thickness measurements
000153618 260__ $$c2011$$bElsevier
000153618 269__ $$a2011
000153618 336__ $$aJournal Articles
000153618 520__ $$aThe classification of macroscale, mesoscale and microscale channels with respect to two-phase processes is still an open question. The main objective of this study focuses on investigating the macro-to-microscale transition during flow boiling in small scale channels of three different sizes with three different refrigerants over a range of saturation conditions to investigate the effects of channel confinement on two-phase flow patterns and liquid film stratification in a single circular horizontal channel (Part 2 covers the flow boiling heat transfer and critical heat flux). This paper presents the experimental two-phase flow pattern transition data together with a top/bottom liquid film thickness comparison for refrigerants R134a, R236fa and R245fa during flow boiling in small channels of 1.03, 2.20 and 3.04 mm diameter. Based on this work, an improved flow pattern map has been proposed by determining the flow patterns transitions existing under different conditions including the transition to macroscale slug/plug flow at a confinement number of Co approximate to 0.3-0.4. From the top/bottom liquid film thickness comparison results, it was observed that the gravity forces are fully suppressed and overcome by the surface tension and shear forces when the confinement number approaches 1, Co approximate to 1. Thus, as a new approximate rule, the lower threshold of macroscale flow is Co = 0.3-0.4 while the upper threshold of symmetric microscale flow is Co approximate to 1 with a transition (or mesoscale) region in-between. (C) 2010 Elsevier Inc. All rights reserved.
000153618 6531_ $$aMinichannels
000153618 6531_ $$aMicrochannels
000153618 6531_ $$aTwo-phase flow patterns
000153618 6531_ $$aTransition
000153618 6531_ $$aBoiling Heat-Transfer
000153618 6531_ $$aGas-Liquid Flow
000153618 6531_ $$aVoid Fraction
000153618 6531_ $$aHorizontal Tubes
000153618 6531_ $$aPressure-Drop
000153618 6531_ $$aDiameter
000153618 6531_ $$aRegimes
000153618 6531_ $$aMicrogravity
000153618 6531_ $$aChannel
000153618 6531_ $$aR134A
000153618 700__ $$aOng, C. L.
000153618 700__ $$g108776$$aThome, J. R.$$0240577
000153618 773__ $$tExperimental Thermal and Fluid Science$$j35$$k1$$q37-47
000153618 909C0 $$xU10312$$0252128$$pLTCM
000153618 909CO $$pSTI$$particle$$ooai:infoscience.tind.io:153618
000153618 917Z8 $$x169307
000153618 937__ $$aEPFL-ARTICLE-153618
000153618 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000153618 980__ $$aARTICLE