Liquid lump flow

Further increase in the gas flow rate in liquid ring flow leads to a liquid lump flow, of which the high-speed core gas entrains the liquid phase and liquid lumps slide... 

Feng, 2001 7l=0.003-17.52 m/s, 7g=0.0012- 295.3 m/s. Steam water, ranges not given diameters of 50 pm for air-water, and 25 pm for steam-water two-phase flow, steam- water details not given patterns identified over the ranges of flow rates studied patterns identified liquid ring flow and liquid lump flow. 

This assumption is more restrictive than the assumption of constant relative volatilities, or relative X-values, that is used in the Fenske and Underwood methods. The payback for this assumption is the ability to generalize the model to different degrees of column complexity. The success of the method is dependent on proper evaluation of effective /C-values or other model parameters that would represent actual behavior of the column section. The equilibrium coefficient is commonly lumped with the vapor and liquid molar flows in the column to define the stripping factor. 

There is, however, a vast body of materials whose behavior as liquids undergoing flow do not satisfy the assumptions for a Newtonian fluid. This includes many polymeric liquids, suspensions, multifluid blends, liquids containing surfactants that tend to form particle-like micelles when they are present at high concentrations, and many others. As we shall subsequently discuss from a qualitative point of view, these fluids exhibit more complicated macroscopic properties and have historically been lumped together under the general designation of non-Newtonian fluids. In the more recent literature, they have also been called complex liquids.20... 

As the dimensions of the channel reduce, Taylor and annular flows dominate, while patterns specific to small channels appear (such as ring, liquid lump, Yakitori and rivulet flows). These can be considered to be variations of the Taylor and annular regimes. For a review of gas-liquid flow patterns in microchannels see Ghiaasiaan and Abdel-Khalik [2]. 

The flow in the glass tube was relatively undisturbed [78]. Partly, bubble formation due to HCl gas evolution and passing of EtjNHCl lumps was observed. These phases were moving with the liquid mixture and were always rinsed out of the tube, and hence were not obstacles causing a breakdown of the flow. 

In the molten state polymers are viscoelastic that is they exhibit properties that are a combination of viscous and elastic components. The viscoelastic properties of molten polymers are non-Newtonian, i.e., their measured properties change as a function of the rate at which they are probed. (We discussed the non-Newtonian behavior of molten polymers in Chapter 6.) Thus, if we wait long enough, a lump of molten polyethylene will spread out under its own weight, i.e., it behaves as a viscous liquid under conditions of slow flow. However, if we take the same lump of molten polymer and throw it against a solid surface it will bounce, i.e., it behaves as an elastic solid under conditions of high speed deformation. As a molten polymer cools, the thermal agitation of its molecules decreases, which reduces its free volume. The net result is an increase in its viscosity, while the elastic component of its behavior becomes more prominent. At some temperature it ceases to behave primarily as a viscous liquid and takes on the properties of a rubbery amorphous solid. There is no well defined demarcation between a polymer in its molten and rubbery amorphous states. 

Dietary preparation involving liquid materials frequently results in either wet feed in which the test article does not disperse or formation of gumballs feed and test material that form discernible lumps and chemical hotspots. Drying and grinding of the premix to a free-flowing form prior to mixing the final diets may be required however, these actions can affect the chemical nature of the test article. 

When liquid is slowly added to a porous solid powder, the liquid is first absorbed in the pores and the powder will flow as if it is dry. When the pores have been filled the outside of the grains rather suddenly become wet, the grains will tend to stick together and the powder will form lumps instead of flowing freely. The situation when the pores have been filled but the outside of the grains is dry is callled incipient wetness and can easily be detected by shaking or stirring the powder. 

Gaseous ammonia is conveniently obtained from a cylinder of the liquefied gas the cylinder must be equipped with a reducing valve. The rate of flow of the gas may be determined by passage through a bubble counter containing a small quantity of concentrated potassium hydroxide solution (12 g of KOH in 12 ml of water). A safety bottle should be inserted between the cylinder and the bubble counter and the reaction vessel the gas may be dried by passage through a column loosely packed with soda lime or calcium oxide lumps (cf. Fig. 4.2). For reactions which require the use of liquid ammonia see Section 2.17.7, p. 116. 

Assuming that the bubble in Prob. 9-27 moves through the liquid at a velocity of 4.5 m/s, estimate the time required to cool the bubble 0.3°C by calculating the heat-transfer coefficient for flow over a sphere and using this in a lumped-capacity analysis as described in Chap. 4. 

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