Liquid velocity effect

The value of zero for m would indicate there is no liquid velocity effect. Increasing values of m would indicate greater velocity effects on the conversion with a value of m=1 describing a situation in which the catalyst efficiency is proportional to the liquid velocity. 

Mixed phase pr ure drop parameter = [(AP/AL), /6 ], dimensionless Modified weiz and Prater Modulus used to test for liquid velocity effects in trickle beds, dimensionless... 

If a gas flows over the surface of a liquid, certain effects ensue. Only the relative velocity of the liquid surface and gas is important in giving rise to nebulization. Thus, some pneumatic nebulizers... 

Wells, S. A. and Dick, R. I. (1993) "Permeability, Solid and Liquid Velocity, and Effective Stress Variations in Compressible Cake Filtration," Proceedings, American Filtration Society Conference on System Approach to Separation and Filtration Process Equipment, Chicago, Illinois, May 3-6, pp. 9-12... 

Column diameter for a particular service is a function of the physical properties of the vapor and liquid at the tray conditions, efficiency and capacity characteristics of the contacting mechanism (bubble trays, sieve trays, etc.) as represented by velocity effects including entrainment, and the pressure of the operation. Unfortunately the interrelationship of these is not clearly understood. Therefore, diameters are determined by relations correlated by empirical factors. The factors influencing bubble cap and similar devices, sieve tray and perforated plate columns are somewhat different. 

Estimate the flood point from Figure 8-137, which accounts for liquid flow effects and is a ratio of liq-uid/vapor kinetic effects [79]. Flooding velocity is obtained from... 

Velocity effects can be achieved either by having the test-piece move through a presumably stationary liquid or by having a moving liquid come into contact with a stationary test-piece. Occasionally tests may involve both types of exposure. Details of test procedures are given in NACE TM 0270-70 Method of Conducting Controlled Velocity Laboratory Corrosion Tests. 

Ross (R2) reported measurements of desulfurization efficiency of fixed-bed pilot and commercial units operated under trickle-flow conditions. The percentage of retained sulfur is given as a function of reciprocal space velocity, and the curve for a 2-in. diameter pilot reactor was found to lie below the curves for commercial units it is argued that this is proof of bad liquid distribution in the commercial units. The efficiency of the commercial units increased with increasing nominal liquid velocity. This may be an effect either of mass-transfer resistance or liquid distribution. 

Nusselt and Reynolds numbers are based on the diameter of the heating element, the conductivity and viscosity of the liquid, and the nominal gas velocities. The heat-transfer coefficient is constant for nominal liquid velocities above 10 cm/sec. The results were obtained for Prandtl numbers from 5 to 1200, but no effect of this variation was observed. 

Chapter 10 deals with laminar flow in heated capillaries where the meniscus position and the liquid velocity at the inlet are unknown in advance. The approach to calculate the general parameters of such flow is considered in detail. A brief discussion of the effect of operating parameters on the rate of vaporization, the position of the meniscus, and the regimes of flow, is also presented. 

Most of heat transfer correlations are based on data obtained in flow boiling from relatively large diameter conduits and the predictions from these correlations show considerable variability. Effects of superficial liquid and gas velocity on heat transfer in gas-liquid flow and its connection to flow characteristics were studied by Hetsroni et al. (1998a,b, 2003b), Zimmerman et al. (2006), Kim et al. (1999), and Ghajaret al. (2004). However these investigation were carried out for tubes of D = 25—42 mm. These data, as well as results presented by Bao et al. (2000) in tubes of L> = 1.95 mm and results obtained by Hetsroni et al. (2001), Mosyak and Hetsroni (1999) are discussed in the next sections to clarify how gas and liquid velocities affect heat transfer. Effects of the channel size and inclination are considered. 

As shown in Fig. 5.42 an increase in superficial liquid velocity involves an increase in heat transfer (Nul). This effect falls off with increasing superficial gas velocity in the range Reos = 4.7-270. 

Fig. 5.42 Effect of superficial liquid velocity on heat transfer in parallel triangular micro-channels of Jh = 130 pm...

The solution of Eq. (10.50) determines the steady states of the liquid velocity, as well as the position of the meniscus in a heated micro-channel. Equation (10.50) can have one, two or three steady solutions. This depends on the value of the parameter (in the generic case parameter B), which takes into account the effect of the capillary forces. 

The effect of the acceleration due to gravity on the steady-state liquid velocity and the meniscus position is shown in Fig. 10.12. An increase in g is accompanied by the displacement of the meniscus toward the inlet and a decrease in the liquid velocity. 

Effect of draft-tube horn-mouth diameter on liquid velocity and gas hold-up... 

Fig.6 and Fig.7 illustrate the effect of draft-tube diameter on liquid superficial velocity, liquid circulating flowrate and gas hold-up. Results show that the liquid superficial velocity in the riser increases with increasing the draft-tube diameter while the liquid velocity in the... 

Fig.6 Effect of downcomer diameter on liquid velocity and flowrate...

The recovery of copper powder from wastewater of electronic industries was investigated in three-phase inverse fluidized-bed electrode reactors(0.102m ID x 1.0m). Effects of gas and liquid velocities, current density, distance between the two electrodes and amount of fluidized particles on the recovery of copper powder were examined. The addition of a small amount of gas or fluidized particles into the reactor resulted in the decrease in the powder size of copper recovered as well as increase in the copper recovery. The value of copper recovery exhibited a maximum with increasing gas or liquid velocity, amount of fluidized particles or distance between the two electrodes but increased with increasing current density. 

The linear velocity of the liquid developing under the effect of this force is zero directly at the solid surface, and increases to some maximum value v at the distance X = 8o from the surface. Solution regions farther out lack the excess charges that could come under the effect of the external electric field hence, there is no further increase in liquid velocity (Fig. 31.4). When the layer (Sg) is much thinner than the capillary radius, 5g r, the assumption can be made that the bulk of the solution moves with a uniform velocity v. 

Let us consider a case of steady evaporation. We will assume a one-dimensional transport of heat in the liquid whose bulk temperature is maintained at the atmospheric temperature, 7 X. This would apply to a deep pool of liquid with no edge or container effects. The process is shown in Figure 6.9. We select a differential control volume between x and x + dx, moving with a surface velocity (—(dxo/df) i). Our coordinate system is selected with respect to the moving, regressing, evaporating liquid surface. Although the control volume moves, the liquid velocity is zero, with respect to a stationary observer, since no circulation is considered in the contained liquid. 

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