Two-phase flow hydraulics

The first version of OLGA was developed through a joint research program between the Institute for Energy Technology and SINTEF, supported by Conoco Norway, Esso Norge, Mobil Exploration Norway, Norsk Hydro A/S, Petro Canada, Saga Petroleum, Statoil, and Texaco Exploration Norway. 

OLGA 2000 (two phase) from Scandpower is a revision of the OLGA model. OLGA 2000 includes improved correlations for wall shear stress, gas entrairanent in the liquid layer, and droplet deposition on the pipe wall in stratified flow. 

Beggs and Brill correlations showed a consistent tendency seriously to overpredict liquid holdup on all data sets except the low-pressure pipeline. 

Process engineering and design using Visual Basic 

Gas Flow MMcum/d Beggs and Brill (Original) Beggs and Brill (Revised) Mukherjee and Brill No-Slip 

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Atomization = Eotvos numher, Eo Two-phase flows, free surface flows Compressible flow, hydraulic transients Cavitation... 

Sizing, safety relief, 436, 437-441 API liquid valve, 444 Balanced valves, 441 Conventional valves, 438 Critical back pressure, 440 Effects of two-phase flow, 437 Hydraulic expansion, 441 Rupture disks, 434 Sub-critical flow, 449 Slurry flow, process pipe, 142-147 Regimes, 143... 

The problems of micro-hydrodynamics were considered in different contexts (1) drag in micro-channels with a hydraulic diameter from 10 m to 10 m at laminar, transient and turbulent single-phase flows, (2) heat transfer in liquid and gas flows in small channels, and (3) two-phase flow in adiabatic and heated microchannels. The smdies performed in these directions encompass a vast class of problems related to flow of incompressible and compressible fluids in regular and irregular micro-channels under adiabatic conditions, heat transfer, as well as phase change. 

For adiabatic, steady-state, and developed gas-liquid two-phase flow in a smooth pipe, assuming immiscible and incompressible phases, the essential variables are pu, pG, Pl, Pg, cr, dh, g, 9, Uls, and Uas, where subscripts L and G represent liquid and gas (or vapor), respectively, p is the density, p is the viscosity, cr is the surface tension, dh is the channel hydraulic diameter, 9 is the channel angle of inclination with respect to the gravity force, or the contact angle, g is the acceleration due to gravity, and Uls and Ugs are the liquid and gas superficial velocities, respectively. The independent dimensionless parameters can be chosen as Ap/pu (where Ap = Pl-Pg), and... 

The experiments of co-current upward air-water two-phase flow patterns in vertical triangular micro-channels were carried out by Zhao and Bi (2001a). Three equilateral triangular channels 270 mm in length, having side lengths of 5.0, 2.5, and 1.5 mm, corresponding to hydraulic diameters of 2.886,1.443, and 0.866 mm, were tested. 

Me et al. (2006) addressed the differences in gas-liquid two-phase flow characteristics that occur in conventional size channels and micro-channels by examining the two-phase flow pattern, interfacial wave, void fraction and friction pressure drop data obtained in circular and rectangular channels with a hydraulic diameter ranging from 50 pm to 6.0 mm. 

The bubble dynamics under conditions corresponding to flow in two parallel trapezoidal micro-channels with hydraulic diameter 47.7 pm was studied by Li et al. (2004). The bubbles in two parallel micro-channels generally grow similarly to that in a single micro-channel. The authors reported on the presence of two-phase flow... 

The development of the two-phase flow in a heated capillary at different Peclet number is illustrated in Fig. 9.13. It shows that different mechanisms of two-phase flow formation may occur depending on the value of Peu. At small Pcl the fine bubble formation (on the micro-channel wall) plays a dominant role. Growth of these bubbles leads to a blockage of the micro-channel, to a sharp change of the hydraulic... 

Void distribution measurement. The local void fraction is an important parameter in the reduction and analysis of hydraulic test data in two-phase flow. In addition to photographic visualization and fiber optic video probes for observation (Donaldson and Pulfrey, 1979), the following other methods are currently available, each with its own unique set of attributes and drawbacks (Delhaye et al., 1973 Delhaye, 1986 Andreychek et al., 1989). 

Jones, O. C., Jr., and S. G. Bankoff, 1977, Two-Phase Flow in Light Water Reactors, Proc. Symp. on Thermal and Hydraulic Aspects of Nuclear Reactors, ASME, Atlanta GA. (3)... 

Malnes, D., and H. Boen, 1970, Dynamic Behavior of Hydraulic Channels, Meeting of European Two-Phase Flow Group, Milan, Italy. (3)... 

Todreas, N. E., and M. S. Kazimi, 1990, Two-Phase Flow Dynamics, in Nuclear Systems I Thermal Hydraulic Fundamentals, pp. 476-479, Hemisphere, Washington, DC. (3)... 

The zero-point analysis characterizes the rotor hydraulics in two ways. First, the zero-point value gives the liquid flow rate over the more-dense-phase weir just as the liquid in the separating zone rises to the edge of the less-dense-phase weir. Second, the slope of the curve above the zero point measures the liquid rise over the more-dense-phase weir relative to the liquid rise over the less-dense-phase weir. Thus, if all rotors in a set have about the same zero point and the same slope above the zero point, then they can all be expected to operate about the same in two-phase flow. 

During vaporization or condensation, thermal and hydraulic performances depend essentially on the two-phase flow structure. Furthermore, as very often in industrial processes, the heat exchanger operates in thermosyphon or under natural circulation knowledge of the pressure drop and liquid holdup is of major importance. But there is very little information on two-phase flow characteristics in compact geometries. 

These definitions rely upon the molecular mean free path in a single-phase flow, surface tension effects and flow patterns in two-phase flow applications. In recent studies in minichannels the hydraulic diameter ranges from 100 /jm to 2-3 mm. The channel cross sections were either circular or rectangular and much of the research concerned boihng. Commonly, classical correlations have been used with or without modifications to predict flow boihng results in minichannels. However agreement was poor and the need for new correlations was evident. 

Coleman, J. W., and Garimella, S. (2000) Two-Phase Flow Regime Transitions in MicroChannel Tubes The Effect of Hydraulic Diameter, American Society of Mechanical Engineers, Heat Transfer Division, Orlando, EL, Vol. HTD-366, American Society of Mechanical Engineers, pp. 71-83. 

Anglart H, Andersson S, Podowski MZ, Kurul N (1993) An Analysis of Multidimensional Void Distribution in Two-Phase Flows. Proc 6th Int Topical Meeting on Nuclear Reactor Thermal Hydraulics NURETH-6, Grenoble, October 5-8, 1 139-153... 

In this section, we consider gas moving equipment for pressure service and then for vacuum liquid moving equipment. Then, two-phase flow is considered in Section 16.11.2.4. Hydraulic conveying of solids is discussed in Section 16.11.2.5. Conveying solids is considered in Section 16.11.2.6, while Sections 16.11.2.7 and 16.11.2.8 address piping and steam. 

R. K. Shah and M. S. Bhatti, Assessment of Correlations for Single-Phase Heat Exchangers, in Two-Phase Flow Heat Exchangers Thermal Hydraulic Fundamentals and Design, S. Kaka(, A. E. Bergles, and E. O. Fernandes (eds.), pp. 81-122, Kluwer Academic Publishers, Dordrecht, Netherlands, 1988. 

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