Liquid viscosity effect

Figure 5.2-20. Liquid viscosity effect on the two-phase pressure drop (after Wild et al. [28]).

Equations (24) through (26) do not include any effects due to liquid viscosity or liquid flow rate. Consequently, the equations are most useful when experimental data for the packing are available at known L/G ratios and liquid viscosities. For design purposes, liquid-viscosity effects can be assumed negligible if the viscosity is under 2 centipoises. Because of errors that may be introduced by neglecting the influence of the liquid rate, use of Eq. (25) or (26)... 

Neglects liquid viscosity effects Liquids used must be water or oil... 

Temperature Temperature affects liquid viscosity, effectiveness of flocculants, dewaterability and may influence materials of construction. 

Fontaine, O., J. Ghilane, P. Martin, J.-C. Lacroix, and H. Randriamahazaka. Ionic liquid viscosity effects on the functionalization of electrode material through the electroreduction of diazonium salts. Langmuir 26, 2010 18542-18549. 

The drop in pressure when a stream of gas or liquid flows over a surface can be estimated from the given approximate formula if viscosity effects are ignored. The example calculation reveals that, with the sorts of gas flows common in a concentric-tube nebulizer, the liquid (the sample solution) at the end of the innermost tube is subjected to a partial vacuum of about 0.3 atm. This vacuum causes the liquid to lift out of the capillary, where it meets the flowing gas stream and is broken into an aerosol. For cross-flow nebulizers, the vacuum created depends critically on the alignment of the gas and liquid flows but, as a maximum, it can be estimated from the given formula. 

Liquid viscosity generally produces adverse effects on drop size. It increases the initial film thickness and hinders the growth of unstable waves. 

Experimental measurements of viscosity almost always are recommended when dealing with slurries and extrapolations should be made with caution. Most theoretically based expressions for liquid viscosity are not appropriate for practical calculations or require actual measurements to evaluate constants. For nonclustering particles, a reasonable correlation may be based on the ratio of the effective bulk viscosity, /ig, to the viscosity of the liquid. This ratio is expressed as a function of the volume fraction of liquid x in the slurry for a reasonable range of compositions ... 

A complicating factor in this process is the formation of finely divided carbon, which causes an increase of liquid viscosity and promotes bubble coalescence whereby the gas-liquid interfacial area is reduced. Also observed was a effect of reactor height, which may be attributed to bubble coalescence. 

Increasing liquid viscosity lowers rate of absorption and equilibrium mass absorbed. During liquid immersion, soluble non-bound ingredients in an elastomer can be removed by leaching—usually (but not always) a small effect. 

The superficial gas velocity Og is G/A, where A is the horizontal cross-sectional area of the empty vertical foam column. Also, g is the acceleration of gravity, p is the liquid density, p is the ordinary liquid viscosity and p, is the effective surface viscosity. 

Table 8-13 Effect of Liquid Viscosity on Packing Efficiency30 ...

A viscosity reducing method based on the selective cleavage of carbon sulfur bonds of aromatic heterocyclic molecules containing a sulfur heteroatom. The physicochemical properties of these heterocycles contribute to the liquid viscosity. The method comprises contacting the liquid with an effective amount of a biocatalytic agent. 

To account for the effect of liquid viscosity on liquid jet breakup, Weber extended Rayleigh s theory to a more general theory for low-velocity j et breakup. In Weber s theory it is assumed that... 

The correlation derived by Dombrowski and Johns covers a large range of liquid viscosity and agrees favorably with experimental results. Crapper et al.[236] further applied second order and large amplitude theories to achieve better predictions. In addition, the effects of surface tension, and viscosity of a liquid sheet as well as the radial spreading and the resultant changes in the sheet thickness on the stability have been examined by Weihs.[257]... 

For liquids of higher viscosities, the influence of liquid viscosity on droplet breakup needs to be considered. According to Hinze,[270] the critical Weber number may be modified to the following expression to account for the effect of liquid viscosity ... 

The liquid properties of primary importance are density, viscosity and surface tension. Unfortunately, there is no incontrovertible evidence for the effects of liquid viscosity and surface tension on droplet sizes, and in some cases the effects are conflicting. Gas density is generally considered to be the only thermophysical property of importance for the atomization of liquids in a gaseous medium. Gas density shows different influences in different atomization processes. For example, in a fan spray, or a swirl jet atomization process, an increase in the gas density can generally improve... 

SMD = A.T y. Q-6 AL a l(smGpLVl))n Derived from fan spray data of water and oil based on a simplified sheet breakup theory Effect of liquid viscosity not included Dombrowski Munday [94]... 

In fan spray atomization, the effects of process parameters on the mean droplet size are similar to those in pressure-swirl atomization. In general, the mean droplet size increases with an increase in liquid viscosity, surface tension, and/or liquid sheet thickness and length. It decreases with increasing liquid velocity, liquid density, gas density, spray angle, and/or relative velocity between liquid and surrounding air. 

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