Falling film number

For falling films applied to the outside of horizontal tubes, the Reynolds number rarely exceeds 2100. Equations may be used for falling films on the outside of the tubes by substituting 7TD/2 for L. 

The Reynolds number of the condensate film (falling film) is 4r/ I, where F is the weight rate of flow (loading rate) of condensate per unit perimeter kg/(s m) [lb/(h ft)]. The thickness of the condensate film for Reynolds number less than 2100 is (SflF/p g). ... 

The gaseous S03 stream (previously diluted with dry air to a concentration ranging from 7% to 2.5% volume) is then fed to the sulfonation/sulfation section which is based on a multitube falling film reactor having a number of tubes proportional to the plant production capacity (Figs. 8 and 9). The S03 gas is fed to the upper part of the reactor and distributed equally to each reaction tube. 

Other in vitro methods include the determination of the weight needed to break the adhesion [41], the fluorescent probe [35], the flow channel [42], mechanical spectroscopy [43], the falling film [44], colloidal gold staining [45], viscometiy [46], the thumb test [47], the adhesion number [47], and electrical conductance [47]. 

As reported in Section III, C, there are numerous theoretical treatments of the problem of the onset of rippling in a falling film. By way of comparing these predictions, the theoretical lines giving the Reynolds number at the onset of rippling, as a function of the channel slope... 

Figure 4.29 Numbered-up, cylindrical , (left) and scaled-up, large , (right, laboratory version in front) falling-film microreactors (by courtesy of IMM).

The hydrodynamics of the falling film governs, as to be expected, the reaction behavior [322,323]. When increasing the flow rate, the reaction time was reduced and the film thickness was increased. For both reasons, the conversion decreased and exhibited in a linear dependence on log Re, Re being the Reynolds number. The hydrogenation conversion had only a weak dependence on hydrogen pressure. 

Pressure, mmHgabe Liquid falling film Dumber, Ct Galileo number. Eg. (8.9)... 

Fig.3 Density of the coexisting liquid phase Fig.4 Weber number of a falling film for the of the system oleic acid/carbon dioxide, oleic system oleic acid/ethane as a function of acid/ethane and pure oleic acid as fuction of ethane activity [4]. pressure [3].

The hydrodynamic behavior of liquid films can be characterized by the dimensionless Weber number We = (82 p g sina)/c. In Figure 4 the Weber number of a falling film (since = 1) is plotted against the activity of ethane for the system oleic acid/ethane. At low temperatures the temperature dependence of the Weber number is small. The Weber number changes little at low activities. For activities greater than 0.8 the Weber number increases sharply. The transition region from the first appearance of instability to disintegration into droplets or trickles corresponds with the sharp increase of the Weber number. 

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