Spiral flow

Lake Texcoco. Lake Texcoco, a few miles northeast of Mexico City, is in the lowest part of the Valley of Mexico. The lake is mostly dry and alkaH is recovered from brine weUs that have been drilled into the underlying stmcture. The brine is concentrated first in a spiral flow solar evaporation pond and further in conventional evaporators. This strong brine is carbonated and then cooled to crystallize sodium bicarbonate which is subsequently filtered and calcined to soda ash. Purity of this product is similar to Magadi material (9,29). 

Type T is the spiraf-spiral flow pattern. It is used for all heating and cooling seiwices and can accommodate temperature crosses such as lean/rich seiwices in one unit. The removable covers on each end allow access to one side at a time to perform maintenance on that fluid side. Never remove a cover with one side under pressure as the unit will telescope out hke a collapsible cup. 

Type 77 units are the condenser and reboiler designs. One side is spiral flow and the other side is in cross flow. These SHEs provide veiy stable designs for vacuum condensing and reboiling seiwices. A SHE can be fitted with special mounting connec tions for refliix-type vent-condenser apphcations. The vertically mounted SHE directly attaches on the column or tank. 

Type 111 units are a combination of the Type I and Type II where part is in spiral flow and part is in cross flow. This SHE can condense and subcool in a single unit. 

There are a variety of new developments in magnetic separation which are of possible interest, but their commercial apphcability is still not yet assured. These include quadripole separators and a spiral-flow device. 

The spiral assembly can be fitted with covers to provide three flow patterns (1) both fluids in spiral flow, (2) one fluid in spiral flow and the other in axial flow across the spiral, and (3) one fluid in spiral flow and the other in a combination of axial and spiral flow. 

Figure 10-9A. Spiral flow heat exchanger, cross-flow arrangement for liquids, gases, or liquid/gaseous (condensable) fluids. (Used by permission Alfa Laval Thermal Inc., Bui. 1205 1993.)...

SF Spiral Flow index, the length of specimen molded into spiral mold Injection molding machine. Allrounder 221-75-350 Arburg... 

However this solution is not always convenient and may prevent high productivity and/or the production of intricate forms which require high temperature processing. Fortunately, some fire retardants dramatically increase the flowability of fire retardant plastics melts. For example ABS, flame retarded with F-2016 or F-2016M (brominated epoxy) has much higher flowability, melt flow index (MFI), and spiral flow index, than virgin ABS (Fig. 1). 

Fig. 1. Flow near a rotating hemisphere electrode. (a) Dye movement at Re = 1300. (b, c) Spiral flow patterns etched on a copper hemisphere.

Centrifugal force can also be used to separate solid particles from fluids by inducing the fluid to undergo a rotating or spiraling flow pattern in a stationary vessel (e.g., a cyclone) that has no moving parts. Cyclones are widely used to remove small particles from gas streams ( aerocyclones ) and suspended solids from liquid streams ( hydrocyclones ). 

The brominated phosphate is an efficient flame retardant for polycarbonate resin. UL-94 ratings of V-0 with oxygen index values of greater than 40 are obtained. Polycarbonate resin containing brominated phosphate processes with greater ease than resin containing brominated polycarbonate as measured by injection molding spiral flow measurements. The heat distortion temperature is reduced... 

The three flame retardants are compared in Table VI. Brominated phosphate disperses readily in the resin presumably due to its high solubility in aromatics. Resin containing brominated polycarbonate is relatively difficult to process as measured by injection molding spiral flow measurements. 

Additionally, macroscopic flow structure of 3-D bubble columns were studied [10]. The results reported can be resumed as follows (a) In disperse regime, the bubbles rise linearly and the liquid flow falls downward between the bubble stream, (b) If gas velocity increases, the gas-liquid flow presents a vortical-spiral flow regime. Then, cluster of bubbles (coalesced bubbles) forms the central bubble stream moving in a spiral manner and 4-flow region can be identified (descending, vortical-spiral, fast bubble and central flow region). Figure 10 shows an illustrative schemes of the results found in [10]. 

ASTMD3123, Thermosetting Molding Compounds, Spiral Flow, Low Pressure, Vol. 8.02, ASTM, Philadelphia, Pa., 1994. 

Quantitative Analysis of Spiral Flow (Combined Shear) and... 

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