Begell House Inc.
Multiphase Science and Technology
MST
0276-1459
19
3
2007
TWO-PHASE PRESSURE DROP AND VOID FRACTION DURING FLOW BOILING OF ISO-OCTANE
211-223
10.1615/MultScienTechn.v19.i3.10
Vishwas V.
Wadekar
Retired Consultant, PS2E Institute
Keith M.
Miller
KBR, Inc.; HTFS, Aspen Technology, Reading, UK
M. E. D.
Urso
Department of Chemical Engineering, Imperial College of Science, Technology and Medicine,
London, United Kingdom; HTFS, Aspen Technology, Reading, UK
The article reports pressure drop data for iso-octane boiling in vertical upflow in a 8-m-long, 25.4-mm i.d. tube, heated by direct electrical heating. The trends of the measured pressure gradient are checked with respect to vapor quality, mass flux, and pressure. After confirming that these trends are systematic, the two-phase pressure drop data are examined in terms of their constituent parts, namely, acceleration, friction, and gravity components. Subsequently, the data dominated by the gravity component are used to back-calculate void fractions, and these are compared with various correlations, including the HTFS void fraction method. Some correlations performed better than others in predicting the void fraction data. It is observed that generally, the measured void fraction is lower than expected in the high vapor quality region, even when the quality approaches near-dryout value. To explain this behavior, a simple model is constructed to calculate void fraction as a function of local vapor quality in the postdryout region.
HEAT TRANSFER AND LIQUID MOTION OF FORCED CONVECTIVE BOILING IN A MINI-TUBE FOR AQUEOUS SOLUTIONS WITH NONLINEAR SURFACE ENERGY
225-240
10.1615/MultScienTechn.v19.i3.20
Naoki
Ono
Department of Mechanical Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan
T.
Yoshida
Department of Mechanical Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan
Masahiro
Shoji
Department of Mechanical Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama, Kanagawa 221-8686; and Energy Technology Research Institute, AIST, 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan
Fumio
Takemura
Energy Technology Research Institute, AIST, 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan
T. H.
Yen
Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST); and Nissan Motors Co., Ltd., 560-2, Okatsukoku, Atsugi, Kanagawa 243-0192, Japan
The value of the surface tension of aqueous solutions of some alcohol, such as butanol, increases from above some temperature when the solution is heated. Evaporation heat transfer of such a nonlinear solution was experimentally investigated. Butanol aqueous solution was adopted as the test fluid. The direction of thermocapillary force in liquid film of a nonlinear surface energy solution on a heated surface acts in the same direction to solute Marangoni force. The surface tension effects are expected to be marked in small-scale systems. The aim of the present study is to investigate the effect of the nonlinear surface tension of butanol aqueous solution on the liquid motion and heat transfer in convective boiling in a single mini channel. The quartz tube whose ID was 1 mm was applied as the test mini tube. The mass flux of the butanol solution was 1.96 kg/m2s. Prior to the experiments, the measurement of the surface tension of the butanol aqueous solution was performed by Wilhelmy's method to compare to the ethanol solution and pure water. From the convective boiling experiments, it was found that the temperature of the outer surface of the tube was much lower in the case of the butanol aqueous solution, at the region where the vapor quality was unity, than in the case of pure water. The liquid droplet motions were also observed by CCD video camera system.
GAMMAS AND X-RAY TOMOGRAPHY OF LIQUID-LIQUID AND GAS-LIQUID-LIQUID FLOWS
241-267
10.1615/MultScienTechn.v19.i3.30
W. L.
Wong
EPTG Pipelines Team, BP Exploration, Sunbury-on-Thames, TW16 7LN, UK
Colin P.
Hale
Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK
B.
Hu
Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK
S. M.
Richardson
Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK
Geoffrey F.
Hewitt
Department of Chemical Engineering & Chemical Technology, Imperial College of Science, Technology & Medicine, Prince Consort Road, London SW7 2B Y, England, UK
This article describes work carried out at Imperial College, London, in which a variety of gamma and X-radiography techniques were applied to the study of flows with two liquid phases (i.e., liquid-liquid two-phase flows and liquid-liquid-gas three-phase flows). Using a series of single-beam, single-energy gamma densitometers, it was possible to obtain data on the evolution of slug velocity and frequency. Using a traversing-beam, dual-energy densitometer, it was possible to obtain tomographic data on average phase distribution and (by conditional sampling) the phase distribution in the slugs. Using a triple-beam, dual-energy gamma densitometer, it was possible to obtain transient phase distribution data in the cross section, though at limited locations. Finally, complete cross-sectional distributions of the phases were obtained using a multibeam X-ray system, again in a form suitable for interpretation using a tomographic algorithm.
A THREE-DIMENSIONAL PIV USING INTENSITY GRADIENTS OF A TWO-COLOR LASER BEAM
269-285
10.1615/MultScienTechn.v19.i3.40
Shigeo
Hosokawa
Faculty of Societal Safety Science, Kansai University, 7-1 Hakubai, Takatsuki,
Osaka 569-1098, Japan
Akio
Tomiyama
Department of Mechanical Engineering, Graduate School Engineering, Kobe
University, 1-1 Rokkodai, Nada, Kobe, Hyogo, 657-8501 Japan
Multiphase flows and turbulent flows are inevitably three-dimensional and, therefore, a three-dimensional three-component PIV (3D3C-PIV), which can measure a three-dimensional distribution of three velocity components in a flow, is required for the understanding of a three-dimensional flow structure. In this study, we developed a 3D3C-PIV by making use of the intensity gradients of a two-color laser beam. The significant features of the present method are (i) a three-dimensional distribution of three velocity components is measurable, (ii) simultaneity in measured vectors is guaranteed perfectly, (iii) the optical system is simple and economical because it does not require scanning optics, high-repetition light sources, and cameras, (iv) the calibration of optical distortion required in a stereoscopic PIV/PTV is not necessary , and (v) the algorithm of image processing is simpler compared with 3D-PTV. Feasibility tests were carried out by applying the developed method to a jet flow and a flow around drops. As a result, the feasibility and potential of the proposed method was confirmed.
APPLICATIONS OF NEUTRON RADIOGRAPHY TO TWO-PHASE FLOW IN INDUSTRIAL MACHINES
287-303
10.1615/MultScienTechn.v19.i3.50
Nobuyuki
Takenaka
Department of Mechanical Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
Hitoshi
Asano
Department of Mechanical Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Two-phase flows are observed in many industrial machines. Visualization and measurement of two-phase flows in real parts of the machines in the real conditions are important to understand the two-phase flow phenomena in the machines from mechanical engineering points of view. Most machines are made of metal, and optical visualization and measurement of two-phase flows in the machines are often difficult. Neutron radiography is suitable for visualization and the void fraction measurement. Neutron radiography was applied to the two-phase flows in the metallic parts of real and simulated machines. Two-phase flow behavior in a simulated tight lattice rod bundle of a nuclear reactor, a plate heat exchanger, a self-vibrating heat pipe, a fuel injection nozzle for a Diesel engine, and a polymer electrolyte fuel cell (PEFC) are presented.