Two-phase flow regimes

Lockhart and Martinelli used pipes of one inch or less in diameter in their test work, achieving an accuracy of about -l-/-50%. Predictions are on the high side for certain two-phase flow regimes and low for others. The same -l-/-50% accuracy will hold up to about four inches in diameter. Other investigators have studied pipes to ten inches in diameter and specific systems however, no better, generalized correlation has been found.The way... 

Haberstroh, R. E. and P. Griffith, The Slug-Annular Two-Phase Flow Regime Transition, Am. Soc. Mech. Engr., Paper 65-HT-52,... 

There has been relatively little work done on the development of two-phase flow regime maps for micro-channels. The general trends of how the transition lines are shifted as the diameter is decreased are unclear. Figure 5.19 shows a flow pattern map obtained for air-water two-phase flow in a 20 pm i.d. silica tube by Serizawa et al. (2002) at nearly atmospheric pressure. 

Fig. 5.20 Two-phase flow regime map for a 100 pm micro-channel. Reprinted from Kawahara et al. (2002) with permission...

Fig. 5.21a-d Comparison of two-phase flow regime maps presented by Kawahara et al. (2003) with (a) Damianides and Westwater (1988), (b) Fukano and Kariyasaki (1993), (c) Triplett et al. (1999a) and (d) Zhao and Bi (2001a). Reprinted from Kawahara et al. (2002) with permission... 

Akbar MK, Plummer DA, Ghiaasiaan SM (2003) On gas-liquid two-phase flow regimes in microchannels. Int J Multiphase Flow 29 855-865... 

Bell, K. J., Taborek, J. and Fenoglio, F. (1970) Chem. Eng. Prog. Symp. Ser. No. 102, 66,154. Interpretation of horizontal in-tube condensation heat transfer correlations with a two-phase flow regime map. 

Figure 3.13 Liquid metal -gas two-phase flow regime map. [From Michiyoshi et al 1986. Copyright 1986 by Hemisphere Publishing Corp., New York. Reprinted with permission.)...

Monsanto Enviro-Chem under the Dyna-Wave trademark case histories can be downloaded from a web site (http //www.enviro-chem. com/airpol/common/rjstop.html). Nonatomizing froth scrubbing is described in those patents as occuring within defining boundaries on a new dimensionless velocity versus dimensionless liquid/gas ratio two-phase flow regime map, shown here as Fig. 17-51. 

For a non-foamy system, the extent of the level swell and the fraction of gas/ vapour entering the pressure relief system, at a given gas/ vapour evolution rate, depends on the two-phase flow regime within the vessel. For non-viscous systems the two main flow regimes are bubbly-flow and churn-turbulent flow (see Figure 4.2 (b) and... 

Wilmarth, T., and Ishii, M. (1994) Two-Phase Flow Regimes in Narrow Rectangular Vertical and Horizontal Channels, International Journal of Heat andMass Transfer, Vol. 37(12), pp. 1749-1758. 

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. 

However, no general correlation is yet available for ki,a and kca in vertical tubular reactors when the two-phase flow regime is different from bubble flow. So for design, scale-up should be based on laboratory data for mass-transfer coefficients and on the ratio of eneigy dissipation terms as in the method defined by Jepsen (J3). For any tubular reactor, great care must be taken with the distributor design and with the size of the inlet section so as to minimize the entrance effects. 

Figure 3-5. Baker parameters for two-phase flow regimes with modified boundaries. Source Baker [15],...

Characteristic Linear Velocities of Two-Phase Flow Regimes... 

Pribyl, D.J., Bar-Cohen, A. and Bergles, A.E., An Investigation of Critical Heat Flux and Two-Phase Flow Regimes for Upward Steam and Water Flow, Proc. of the International Conference in Boiling Heat Transfer, May 4-8, 2003, Jamaica. 

When the liquid arrives at the reboiler base, it is usually subcooled because of the effect of static pressure and heat losses from the line. When the liquid enters the tubes, heat is applied to the liquid. Initially, the subcooled liquid is heated to its boiling point by sensible heat transfer only. After the boiling point is reached, vaporization begins and two-phase flow regimes are established. 

Pressure oscillations as high-density liquid impinges upon hot channel walls were also recognized as a potential problem, not only in the two-phase flow regime, but also at pressures and temperatures higher than critical, since there is no assurance that phase equilibrium w ill always prevail throughout the flow channels. 

Hassan, 1., Vaillancourt, M., and Pehlivan, K. (2005) Two-phase flow regime transitions in microchannels a comparative experimental study. Microscale Thermophys. Eng., 9 (2), 165-182. 

The most widely quoted flow pattern maps for predicting the transition between two-phase flow regimes for adiabatic flow in horizontal tubes are those of Baker (1954) and Taitel and Dukler (1976). The Baker (1954) map for horizontal two-phase flow in tubes is presented with coordinates ritg/X and In order to use the map first the mass velocities of the liquid (m ) and vapor (wig) must be determined. Then the parameters lambda X and j/ are calculated using the following equations ... 

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