Turbulent flow line sizing

Nozzle Diameter, d Nozzle exit diameter will be equal to or less than the diameter of the line feeding the tank. For a known flow rate of fluid supplied to the jet, the diameter is set by the largest size that will satisfy the requirement that the jet be turbulent or will satisfy the nozzle discharge velocity requirement (if the jet is denser than the tank liquid). For a turbulent flow requirement (both heavy and light jets) ... 

It can be seen from Hgure I4.A.3 that up to step 6, a scale-up exponent of 0.67 can be chosen. This corresponds to a power/unit volume scale-up criteria in line with mass transfer and equal droplet sizes in turbulent flow. Above step 6, then, an exponent of 1.0 can be chosen corresponding to a tip speed criteria for scale-up (similar to that found for motion in yield stress fluids). 

A new on-line approach to SPE is the use of so-called turbulent flow chromatography which combines rapid mobile phase linear velocities with larger particle sizes this approach was discussed in Section 3.5.9 in the context of breakdown of the conventional (van Deemter) rate theory. Whether or not the flow can truly be described as turbulent (Ayrton 1998), there is no question that eddies are formed that enhance the interactions of smaller molecules with the stationary phase. In contrast the large proteins and other biopolymers have rates of mass transfer from the liquid to stationary phase (C term in the van Deemter equation) that are too... 

The heat-transfer phenomena for forced convection over exterior surfaces are closely related to the nature of the flow. The heat transfer in flow over tube bundles depends largely on the flow pattern and the degree of turbulence, which in turn are functions of the velocity of the fluid and the size and arrangement of the tubes. The equations available for the calculation of heat transfer coefficients in flow over tube banks are based entirely on experimental data because the flow Is too complex to be treated analytically. Experiments have shown that, in flow over staggered tube banks, the transition from laminar to turbulent flow Is more gradual than in flow through a pipe, whereas for in-line tube bundles the transition phenomena resemble those observed in pipe flow. In either case the transition from laminar to turbulent flow begins at a Reynolds number based on the velocity in the minimum flow area of about 100, and the flow becomes fully turbulent at a Reynolds number of about 3,000. The equation below can be used to predict heat transfer for flow across ideal tube banks. 

Mold cooling or temperature control is typically done with a thermolator that pumps water, water and ethylene glycol mixtime, or oil through channels in the mold to heat or cool the plastic. Heat transfer (usually cooling) problems develop if corrosion or deposits accumulate in the channels (water lines) in the mold. Other issues are that water lines are not drilled uniformly around the part, coolant lines are not routed correctly, or coolant flow is not tin-bulent. Flow turbulence is defined by a Reynolds number of 3500 or greater and is difficult to achieve in some plants because of inadequate feed and retirni line size or restrictions in the tools cooling... 

In-line mixers are used for continuous mixing in a fluid stream - tending to operate with much smaller continuous inventories than batch or semi-batch stirred tanks. The uniformly distributed turbulent flow in in-line mixing units helps to ensure that the bubbles or drops generated within them tend to have a controllable size distribution within a narrow range. Most mixers are located in pipe work or tubes. 

Thus plotting IIi as a function of 112, the Reynolds number, produces smooth curves with parametric lines described by 113/2, which is shown in Fig. 4.1. Fig. 4.1 shows Hi as a function of Reynolds number for a variety of spherical particles in a number of different diameter pipes. d(s) identifies sphere diameter. The curves are distinguished by the parametric 113/2, which is LchJD. Fig. 4.1 shows that IIi collapses to a common horizontal line in the turbulent flow regime, that is, at high Reynolds numbers. This horizontal line corresponds to the Burke—Plummer result. For low Reynolds numbers, the correlation for each size sphere is negatively sloped, which corresponds to the Blake—Kozeny result. However, unlike the Ergun equation, the different sized spheres each produce a different correlation in the laminar flow... 

In the turbulent flow range of the liquid, the liquid load up and the packing size d have the biggest influence on the liquid hold-up hp. In the laminar range, the hold-up is not only influenced by the variables up and d, but also by the physical properties, viscosity t l and density pp, of the liquid as well as, to some extent, by the surface tension ap [22,44]. In the range below the loading line, the gas has practically no influence on the liquid hold-up hp, see e.g. Fig. 2-3. 

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