Begell House Inc.
Multiphase Science and Technology
MST
0276-1459
14
1
2002
LIQUID FILM THICKNESS MEASUREMENT
74
10.1615/MultScienTechn.v14.i1.10
W. W.
Clark
School of Chemical, Environmental and Mining Engineering, University of Nottingham, United Kingdom
The extensive information available in the literature for liquid film thickness measurement in multiphase systems has been critically reviewed. The review is structured by classification of the identified measurement techniques into groups of comparable measurement resolution. Each technique is reviewed in terms of development history, methodology and technical requirements. Information on the measurement accuracy of each technique and the results of comparative tests between techniques is supplied, where available. The review concludes with the author’s thoughts on recommendation of specific techniques dependent on measurement environment and required resolution.
HEAT TRANSFER TO A SLIDING VAPOUR BUBBLE
20
10.1615/MultScienTechn.v14.i1.20
D. B. R.
Kenning
School of Engineering and Design, Brunel University, Uxbridge, West London, United Kingdom ; Department of Engineering Science Oxford University, Oxford, OX1 3PJ, UK
O. E.
Bustnes
Oxford University, Department of Engineering Science, Parks Road, Oxford OX1 3PJ, UK
Y.
Yan
City University, Department of Aeronautical and Mechanical Engineering, London ECIV OHB
Sliding bubbles play an important part in flow boiling inside and outside tubes but there have been few detailed studies of the mechanisms by which they grow and enhance heat transfer. In this paper the flows of heat into one particular steam bubble sliding underneath a sloping plate in saturated water are studied experimentally and analytically. It is shown that, for this bubble, the local variations in wall temperature are consistent with evaporation from a microlayer 50 - 70 μm thick, but this accounts for only 25 to 35% of the total heat flow into the bubble deduced from its rate of growth.
PRESSURE GRADIENT PREDICTION IN VERTICAL COUNTER-CURRENT FLOWS
13
10.1615/MultScienTechn.v14.i1.30
L.
Lau
Department of Chemical Engineering and Chemical Technology Imperial College of Science, Technology and Medicine London SW7 2BY
M. A. Mendes
Tatsis
Department of Chemical Engineering and Chemical Technology Imperial College of Science, Technology and Medicine London SW7 2BY
Geoffrey F.
Hewitt
Department of Chemical Engineering & Chemical Technology, Imperial College of Science, Technology & Medicine, Prince Consort Road, London SW7 2B Y, England, UK
A prediction methodology for pressure gradient in vertical counter-current air-water flow is presented based on empirical data for downward falling film flow at 3.78 ґ 10-3, 10.08 ґ 10-3, 2.52 ґ 10-3 and 37.80 ґ 10-3 kg/s in the presence of an upward air stream flowing rates ranging from ~ 2.5 ґ 10-4 to 142.0 ґ 10-4 kg/s. The method devised is an extension of the previous study by Hewitt et al. (1965) and has been developed to have as input the length of tube and air and liquid falling film flow rates.