Effect of Gas Flow on Discharge

With more specific reference to agitated systems, information is lacking on the effects of gas bubbles on basic properties like mean flow pattern, impeller discharge rate, or turbulence characteristics. The observations presented in Section II, based mainly on one-liquid-phase data, must therefore be considered as the best available approximations for the flow regimes in gas-liquid agitated systems. There have been a few papers of somewhat basic nature with direct application to these systems and these will be discussed in the remainder of this section. 

Figure 9.5 Effect of gas flow rate on weight loss of nylon 6 treated by air plasma for 5 min. key Q, plasma discharge at 100W , TOW A, SOW A, SOW.

The graph of Figure 6.8 illustrates the effect of increasing voltage on the electric current between two electrodes immersed in a gas. The circuit is completed by an external resistance, used to limit the current flow. As shown in Figure 6.8, the discharge can be considered in regions, which are described below. 

Numerous studies of NO removal in DBD have been carried out [20-36], The effect of electrode shape, discharge gap length, discharge polarity, gas composition and flow rate, and operation temperature on NO conversion will be considered. 

Corona discharges have been investigated extensively for NO removal [38-54], The effect of electrodes configuration, electrical circuit, gas composition and flow rate were studied. When the discharge was operated in pulsed mode, the influence of pulse rise time, duration, and repetition frequency, as well as the effect of the voltage polarity on NO conversion, were considered by numerous authors. 

Fig. 9.4.10 Apparatus for the gas flow-arc plasma method. The apparatus is composed of two components. The upper part is a glass Dewar, which accumulates small particles in a cryogenic matrix on the trim cooled with liquid nitrogen (LN). Sorv, inlet of organic vapor Syr, syringe for transferring produced colloids under anaerobic conditions RP, rotary pump S, target sample. Lower part is for plasma discharge. A BN furnace has gas inlets (G) and is specially designed for Ar gas to flow in screwed stream hence the plasma is emitted in a jet flame due to a plasma pinch effect. The black parts are copper electrodes cooled by water. In order to maintain a constant spacing between the surface of sample and tbe upper electrode, the sample position can move vertically so that the current through the sample to the upper electrode is precisely controlled and constant. This is very important to produce powders with a narrow size distribution.

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