Gas–liquid two-phase flow division at a micro-T-junction A. Azzi 1 , A. Al-Attiyah, Liu Qi, W. Cheema, B.J. Azzopardi à Process and Environmental Engineering Research Division, Faculty of Engineering, University of Nottingham University Park, Nottingham, NG7 2RD England, UK article info Article history: Received 21 November 2009 Received in revised form 27 January 2010 Accepted 24 March 2010 Available online 27 March 2010 Keywords: Gas–liquid Micro-T-junction Phase split Horizontal abstract The phase distribution of a gas–liquid flow through a 1 mm T junction has been studied. Gas superficial velocities of 2.5 and 4.9 m/s and liquid superficial velocities 0.09–0.42 m/s were investigated. Increasing the liquid superficial velocity was shown to decrease the liquid taken off at the side arm. Increasing the gas superficial velocity was found to affect the phase split by increasing the fractional liquid taken off. It was noticed that pressure has no influence in the phase split when it was increased from 0.13 to 0.18 MPa. From examination of data from different pipe sizes, it was seen that the 1 mm T-junction shared similar split characteristics as those observed for larger diameter junctions. Finally, the gas–liquid flow pattern through the junction was observed to be slug for a range of gas and liquid superficial velocities. & 2010 Elsevier Ltd. All rights reserved. 1. Introduction The simultaneous flow of gas and liquid occurs over in a wide range of industrial equipment from large diameter pipes found in the oil and gas production industry to the micro-channels which might be employed to cool electronic components. In many arrangements it is necessary to divide the flow into two or more channel motivated by area restrictions or process requirements. There are no major problems in designing a junction to separate a single-phase flow as empirical equations are available as indi- cated by Azzopardi (1999) in his extensive review of the field. It has been reported that when multiphase streams divide junctions, there is an almost inevitable maldistribution of the phases which could cause downstream equipment to malfunction if the same phase ratio was expected from each outlet. A junction can be defined as three connected pipes. If one is an inlet and the other two are outlets, it is termed a dividing junction. The system with two inlets and one outlet is termed a combining junction. Though, for dividing junctions, the outlet pipes can be at any angle to the inlet, two geometries are commonly found. In that termed side arm junction one outlet is in-line with the inlet; the other outlet is perpendicular to these. In impacting junctions both outlets are perpendicular to the inlet. In the present work side arm dividing junctions are considered. The orientation of the pipes is also important. Junctions can be classified as horizontal or vertical depending on the orientation of the inlet pipe. The most important dimensions of a junction are the diameters of the pipes, D 1 , D 2 , D 3 , where 1 refers to the inlet pipe, 2 to the straight through continuation and 3 to the side arm. Azzopardi (1999) has noted that side arm junctions usually have D 1 ¼D 2 . The division of gas/liquid flows at a dividing junction depends on the resistance (pressure drops) in the two outlet pipes as well as the physical phenomena which affect the phase split. In practical applications, these resistances are caused by equipment downstream of the junction. In experimental studies, it is usual to place valves in the downstream lines. Altering the valve position changes the downstream resistance. In this way it is possible to go from zero take off through the side arm (infinite resistance in the side arm to 100% take off (infinite resistance in the straight-through pie downstream of the junction). Examples of problems resulting from maldistribution are recorded by Azzopardi (1999). These came from natural gas distribution, chemical, and oil/gas production and processing industries. For instance, a problem associated with the gas distribution industry first reported by Oranje (1973) occurs during winter when heavier hydrocarbons condense out of natural gas flow causing a small amount of condensate which is normally negligible. The particular system had a single source and multiple delivery stations. Large amounts of liquid were reported to appear at one of the delivery stations. It was established that this was caused by the maldistribution at a junction used to divide the flow between delivery stations. Another example has been reported in the chemical industry details of which are given in Azzopardi (1999). Mal-operation was noted in a bank of air-cooled heat exchangers operating in parallel that were being used as condensers. Junctions were used to divide the flow into each condenser. However, the last condenser was found to underperform. After investigations, maldistribution caused by the junctions was found to be the reason of the problem. The ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ces Chemical Engineering Science 0009-2509/$ - see front matter & 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.ces.2010.03.037 à Corresponding author. Tel.: + 44 115 951 4160; fax: + 44 115 951 4115. E-mail address: barry.azzopardi@nottingham.ac.uk (B.J. Azzopardi). 1 Visiting from U.S.T.H.B./F.G.M.G.P., B.P. 32, El Alia, Bab Ezzouar, Alger 16111, Algeria. Chemical Engineering Science 65 (2010) 3986–3993