Slug flow regime

Experiments in annular and slug flow were carried out also by Ghajar et al. (2004). The test section was a 25.4 mm stainless steel pipe with a length-to-diameter ratio of 100. The authors showed that heat transfer coefficient increases with increase in liquid superficial velocity not only in annular, but also in slug flow regimes. 

Another instability mode of interest is due to the flow regime itself. For example, it is well known that the slug flow regime is periodic and that its occurrence in an adiabatic riser can drive a dynamic oscillation (Wallis and Hearsley, 1961). In a BWR system, one must guard against this type of instability in components such as steam separation standpipes. The design of the BWR steam separator complex is normally given a full-scale, out-of-core proof test to demonstrate that both static and dynamic performance are stable. 

When bubbles and drops rise or fall in bounded media their shape is affected by the walls of the container. If the bubble or drop is sufficiently large, it fills most of the container cross section and the slug flow regime results. A photograph of a slug flow bubble is shown in Fig. 2.4i. The effect of bounding walls is treated in Chapter 9. 

Slug flow regime, in which slugs of liquid and gas of various sizes occur... 

The above relation covers the parts of both the bubble-flow and pulsed.- (or slug-) flow regimes. Z is defined in Fig. 7-4. 

One unique feature of the monolith reactor is the possibility of having an internal recirculation of the gas flow without the use of a pump [5,8-10]. This self-recirculation is possible due to the very low net pressure drop across the monolith. In a monolith reactor with downflow operation in slug flow regime, the fluids are not driven through the channels by an external pressure, but pulled through by gravity. This corresponds to a total superficial velocity of about 0.45 m sec . When liquid is added to the channel at a lower rate, gas will be entrained to make the total velocity 0.45 m sec. ... 

THIS PROGRAM CALCULATES THE TWO PHASE FLOW MODULUS AND PRESSURE DROPS FOR SLUG FLOW REGIME. 

Chum flow. Here the slug flow regime breaks down to form a region in which liquid is carried upward in large waves, between which a liquid film at the wall may fall downward. Annular flow. Here there is a liquid film carried upward on the walls of the channel, with the vapor flowing in the center of the channel. Usually the vapor contains a dispersion of fine droplets of liquid entrained from the liquid film. 

Although Ae slug flow regime is defined by low gas holdup and is observed in small BCs, small BCs do not necessarily have low gas holdup. The smaller BC diameter may limit the bubble size distribution, which can lead to smaller bubbles, increase stability, and sustain a higher gas holdup. Once the column diameter is... 

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