OP-II-3

PP-I-1influence of the direction of a gas–liquid flow on the velocity of bubbles is explained.The value of a critical capillary number predicted by Taylor for a horizontal capillary(0.707) is theoretically confirmed.A method for calculating the void fraction and relative size of bubbles at theknown flow rates of phases is constructed using the mathematical model (1)-(7). It isshown that the void fraction depends not only on the dynamic gas holdup, but also onthe capillary number and the Weber number, as well as on the direction of the flow.The calculated results are in good agreement with the experimental data of otherresearchers [4, 5].Our experimental set-up consisted of horizontal glass capillary with a length355 mm and inner diameter 0.92 mm; injection needle for gas inlet to capillary. Gasflow rate is regulated by needle valve and measured by Honeywell AWM 43300Vsensor. Liquid is delivered by peristaltic pump Heidolph PD5206. Pressure drop intwo points of capillary – entrance and exit is measured by Elemer AIR-20M5 sensors.Pressure losses were taken into account in further data processing. Liquid sluglength and bubble length were estimated by photography with Nikon D60 body andNikon DX AF-S Nikkor 18-55 mm lens (exposure 1/125 s, photo size 3872x2592 pix,length of single bubble was more than 24 pix).Two infrared sensors are used to define gas bubble velocity. There is 230 mmbetween inlet to capillary and first infrared sensor. Signals from sensors wereconverted from analog to digital for further processing on the computer. Then we cancalculate gas bubble velocity knowing time difference between two signals that areprocessed with correlate function. Experiments were conducted in air-water and airglycerinsystems. Set-up construction and tolerance of our instruments are madepossible to carry out experiments for liquid 0.17 – 0.73 m/s and air 0.09 – 0.56 m/s.Obtained experimental data are in good agreement with our theoretical model.References[1]. Abiev, R.Sh., Simulation of the Slug Flow of a Gas–Liquid System in Capillaries, Theor. Found.Chem. Eng., 2008, vol. 42, no. 2, p. 105.[2]. Abiev, R.Sh., Circulation and By-Pass Modes of the Slug Flow of a Gas–Liquid Mixture inCapillaries, Theor. Found. Chem. Eng., 2009, vol. 43, no. 3, p. 298.[3]. Abiev, R.Sh., Method for Calculating the Void Fraction and Relative Length of Bubbles under SlugFlow Conditions in Capillaries, Theor. Found. Chem. Eng., 2010, vol. 44, no. 1, p. 86.[4]. Kreutzer, M.T., Kapteijn, F., Moulijn, J.A., et al., Inertial and Interfacial Effects on Pressure Drop ofTaylor Flow in Capillaries, AIChE J., 2005, vol. 51, p. 2428.[5]. Liu, H., Vandu, C.O., and Krishna, R., Hydrodynamics of Taylor Flow in Vertical Capillaries: FlowRegimes, Bubble Rise Velocity, Liquid Slug Length, and Pressure Drop, Ind. Eng. Chem. Res.,2005, vol. 44, p. 4884.219