Internal hollow spaces

Internal hollow spaces can be produced, and hence, the principle of conformal cooling can be implemented in terms of manufacturing technology. 

The most common tools in plastics processing are molds. A mold is a premade object, which is used to guide the final form or shape of another object. Molds can be open, like a baking pan, allowing for soft or molten material to be poured or draped over the mold surface. After the material cools or solidifies into its final shape, it is then removed from the mold, and the mold is used again. Molds can also be closed, with internal hollow spaces, allowing soft or molten material to fill these spaces. Closed molds are usually made of several parts, and fabricated in such a way that the mold can be opened, allowing for part removal after the plastic material has solidified. 

Figure 14.6 shows the most common ME cells in which polymeric hollow fibers are inserted into capillary tubes. Water samples can be fed into the membrane, in which case the stripping gas will flow through the space between the membrane and the capillary. Otherwise samples can be fed between the membrane and the probe, and the stripping gas passes through the internal membrane space. In any of these configurations aqueous and gas streams flow in countercurrent. 

Internal gas pressure (approx. 200 bar) Impresses cavity precisely upon undefined interior hollow space contour... 

Area 1 is the "hollow space" between area 2 and the spherical container. This area will be decontaminated where necessary to bring the contamination level below 4 Bq/cm2. The few internally contaminated components which are in the area will be sealed with adequate care (e.g. sealing of valve stems etc.). 

A basic stirred tank design is shown in Fig. 23-30. Height to diameter ratio is H/D = 2 to 3. Heat transfer may be provided through a jacket or internal coils. Baffles prevent movement of the mass as a whole. A draft tube enhances vertical circulation. The vapor space is about 20 percent of the total volume. A hollow shaft and impeller increase gas circulation (as in Fig. 23-31). A splasher can be attached to the shaft at the hquid surface to improve entrainment of gas. A variety of impellers is in use. The pitched propeller moves the liquid axially, the flat blade moves it radially, and inclined blades move it both axially and radially. The anchor and some other designs are suited to viscous hquids. 

As a result of their form, hollow stirrers utilize the suction generated behind their edges (Bernoulli effect) to suck in gas from the head space above the liquid. As rotating ejectors , they are stirrers and gas pumps in one and are therefore particularly suitable for laboratory use (especially in high pressure autoclaves) because they achieve intensive gas/liquid contacting via internal gas recycling without a separate gas pump [58/1]. A particularly effective type of this stirrer - the pipe stirrer - is depicted in Fig. 28. 

Meniscus Regression. The meniscus regression method is comparable to the weight loss method in its simplicity and rapidity. The increase in the length of the void space between the open end of the hollow fiber and the meniscus of the column of liquid is measured periodically using a Wilder Varibeam optical comparator which has been described by Weatherston et. al. (3). Since this instrument can also be used to measure tFe internal diameter of the fiber, the volume and therefore the weight of material lost can be calculated as a function of time. 

The tooling is closed, but there is an uncontrolled internal space between the walls. Thus, all ribs and bosses must be hollow. Additional structural support can be attained by designing the walls or bosses from each side to meet. These contact surfaces will weld together and are known as tack-offs. Male and female threads and threaded inserts can be molded in from the outside surfaces. 

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