{"title":"Vapor Bubble Dynamics in Upward Subcooled Flow Boiling During Void Evolution","authors":"Rouhollah Ahmadi, Tatsuya Ueno, Tomio Okawa","volume":69,"journal":"International Journal of Mechanical and Mechatronics Engineering","pagesStart":1999,"pagesEnd":2007,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/12496","abstract":"Bubble generation was observed using a high-speed\ncamera in subcooled flow boiling at low void fraction. Constant heat\nflux was applied on one side of an upward rectangular channel to\nmake heated test channel. Water as a working fluid from high\nsubcooling to near saturation temperature was injected step by step to\ninvestigate bubble behavior during void development. Experiments\nwere performed in two different pressures condition close to 2bar and\n4bar. It was observed that in high subcooling when boiling was\ncommenced, bubble after nucleation departed its origin and slid\nbeside heated surface. In an observation window mean release\nfrequency of bubble fb,mean, nucleation site Ns and mean bubble\nvolume Vb,mean in each step of experiments were measured to\ninvestigate wall vaporization rate. It was found that in proximity of\nPNVG vaporization rate was increased significantly in compare with\ncondensation rate which remained in low value.","references":"[1] S. C. Lee and S. G. Bankoff, Prediction of the onset of flow instability\nin transient subcooled flow boiling, Nuclear Engineering and Design,\nVol. 139, 1993, pp. 149-159\n[2] P. G. Kroeger, N. Zuber, An analysis of the effects of various parameters\non the average void fractions in subcooled boiling, International Journal\nof Heat and Mass Transfer, Vol. 11, 1968, pp. 211-233.\n[3] S. C. Lee and S. G. Bankoff, A Comparison of Predictive Models for the\nOnset of Significant Void at Low Pressures in Forced-Convection\nSubcooled Boiling, KSME International Journal, Vol. 12, No. 3, 1998,\npp. 504-513\n[4] S. Levy, Forced convection subcooled boiling prediction of vapor\nvolumetric fraction, International Journal of Heat and Mass Transfer 10,\n1967, pp. 951-965.\n[5] P. Saha, N. Zuber, Point of net vapor generation and vapor void fraction\nin subcooled boiling, Proceedings of the 5th Heat Transfer Conference,\nTokyo, Japan, 1974, pp. 175-179.\n[6] Bowring, R. W., 1962, Physical Model Based on Bubble Detachment\nand Calculation of Steam Voidage in the Subcooled Region of a Heated\nChannel, HPR-10, Institutt for Atomenergi, Halden, Norway.\n[7] J.T. Rogers, M. Salcudean, Z. Abdullah, D. McLeod, D. Poirier, The\nonset of significant void in up-flow boiling of water at low pressure and\nvelocities, International Journal of Heat and Mass Transfer 30, 1987, pp.\n2247-2260.\n[8] J.G. Collier, J.R. Thome, Convective Boiling and Condensation, third\ned., Oxford University Press, Oxford, 1994. pp. 325-374.\n[9] G. R. Warrier & V. K. Dhir , Heat Transfer and Wall Heat Flux\nPartitioning During Subcooled Flow Nucleate Boiling\u00d4\u00c7\u00f6A Review,\nJournal of Heat Transfer 128, 2006, pp. 1243-1256.\n[10] R. Ahmadi, T. Ueno, T. Okawa, Bubble dynamics at boiling incipience\nin subcooled upward flow boiling, International Journal of Heat and\nMass Transfer 55 (1-3), 2012, pp. 488-497.\n[11] Dix, G. E., Vapor Void Fraction For Forced Convection with Subcooled\nBoiling at Low Flow Rates, 1971, Ph.D. thesis, University of California,\nBerkeley.\n[12] E.L. Bibeau, M. Salcudean, A study of bubble ebullition in forcedconvective\nsubcooled nucleate boiling at low pressures, International\nJournal of Heat and Mass Transfer 37, 1994, pp. 2245-2259.\n[13] T. Okawa, T. Ishida, I. Kataoka, M. Mori, Bubble rise characteristics\nafter the departure from a nucleation site in vertical upflow boiling of\nsubcooled water, Nuclear Engineering and Design 235, 2005, pp. 1149-\n1161.\n[14] O. Zeitoun, M. Shoukri, Bubble behavior and mean diameter in\nsubcooled flow boiling, Transactions of ASME, Journal of Heat\nTransfer 118, 1996, pp. 110-116","publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 69, 2012"}