Volume rate of flow

There is a minimum air (or gas) volume rate of flow that must be maintained in order to adequately clean the bottom of the hole of cuttings and carry these... 

Positive displacement vacuum pumps. Measurement of performance characteristics. Part 1 - Measurement of volume rate of flow (pumping speed) 12/93... 

The speed at which the metal moves through the rollers must change in order to keep the volume rate of flow constant through the roll gap. Hence, as the thickness decreases, the velocity increases. However, the surface speed of the roller is constant, so there is relative sliding between the roller and the metal. The direction of the relative velocity changes at a point along the contact area called the neutral or no-slip point (point N in Figure 7.10). At the neutral point, the roller and metal have the same... 

Gas flow through the sampling orifice is of interest since its volume rate of flow determines the size of vacuum pumps necessary for the mass spectrometer. In addition, orifice flow behaves as a first-order removal process that can lead to erroneous kinetics if it is too large. The perturbation of flow in the reactor has been discussed in Section IV.B. 

The situation is more complicated if expansion or contraction of a volume element does occur and the volumetric flowrate is not constant throughout the reactor. The ratio VJv, where v is the volume flow into the reactor, no longer gives the true residence time or contact time. However, the ratio VJv may still be quoted but is called the space time and its reciprocal v/V, the space velocity. The space velocity is not in fact a velocity at all it has dimensions of (time) 1 and is therefore really a reactor volume displacement frequency. When a space velocity is quoted in the literature, its definition needs to be examined carefully sometimes a ratio Vi/ V, is used, where V/ is a liquid volume rate of flow of a reactant which is metered as a liquid but subsequently vaporised before feeding to the reactor. 

Stirred tanks are usually employed for reactions in liquids and, in most cases, the mass density of the reaction mixture may be assumed constant. Material balances may then be taken on the basis of the volume rate of flow v which is constant throughout the system of tanks. The material balance on A over tank r may thus be written, in the steady state ... 

Total Surface Area of Droplets iVolume Rate of Flow of Gas /... 

Figure lb. Insert is a plot of the change in SO2 concentration as a function of exposed droplet surface area normalized by the volume rate of flow of gas, for different droplet sizes and droplet velocities. (Reproduced with permission from reference 7. Copyright 1987 American Geophysical Union.)... 

The equation of state for a perfect gas is presented and expressions arising from this for pure gases and gas mixtures are given. The kinetic theory of gases, which is a useful model of perfect gases, is introduced and two particularly useful results are emphasised. These are the mean free path (/) and the mean or thermal velocity (c). Of particular importance is Z74, which is numerically equal to the volume rate of flow per unit area and which can be used to determine quantities such as area-related pumping speeds, conductances, etc. 

The volume rate of flow (A v) = volume/time can be obtained ... 

Pumping speed (typical units Ls1 m3h ) generally refers to the volume rate of flow of gas entering the vacuum pump. Manufacturers state the pumping speed of a pump at the inlet of the pump (SQ, in this... 

Figure 3.1 Pumping speed (volume rate of flow) as a function ofpressure (S0 = 65 m2 hr1)...

Sb = volume rate of flow of gas transported by adsorption (on forevacuum side) - desorption (at inlet side) by the impellers... 

This equation predicts that the distribution of velocities in the tube can be represented by a parabola, as in Fig. 2b. The volume rate of flow past a given point (volume per unit time) is... 

J. R. Katzer We were concerned with the question of equal volume rates of flow during counterdiffusion but did not attempt to measure the two flow rates this would be extremely difficult in a freely and quite rapidly counterdiffusing system as was the case here. Note, however, that the total volume flow in each direction should have been essentially the same unless there were some strange phenomena which occurred at intermediate composition because it was found that the volume of pure compound sorbed at saturation based on the liquid density at sorption temperature was essentially the same for all components studied here. 

The pumping rate was adjusted according to the desired residence time, R, which is defined as the working capacity of the reactor divided by the total volume rate of flow through the reactor. For instance, if the reactor has a capacity of 3 liters, a rate of 1.5 liters per hour for each of the two solutions corresponds to a residence time of 1 hour. 

The validity of this equation is observed by noting that v BL represents the hypothetical volume rate of flow of gas passing the collection area, while q is the volumetric flowrate of gas entering the unit to be treated. An alternate but equivalent form of the above equation is... 

Assume the suspended solids (SS) are related to the volume rate of flow of water (q) through the relationship ... 

Paradoxically, the range of flow rates (or Reynolds numbers) for which the assumption of laminar flow can be used in practice is bounded below (rather than above). Indeed, there is [500] a threshold value Qmin of the volume rate of flow per unit film width such that for Q < Qmin the flow in separate jets is energetically favorable. It was theoretically established in [191] that... 

The volume rate of flow per unit width is given by the formula... 

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