Atmospheric Pressure Hot-Wall Reactor

Three different reactors were used to deposit CuInS2 films via AACVD. Reactor A, shown schematically in Fig. 6.11a, was primarily used in the parametric studies described below. This is a horizontal, atmospheric pressure, hot-wall reactor with a plate-type 2.5-MHz ultrasonic nebulizer from Sonaer Ultrasonics. The precursor (1.5-3.5g) was dissolved into distilled toluene (50-400 ml) and fed into the nebulizer using a syringe pump. The nebulizer... 

ATMOSPHERIC PRESSURE HOT-WALL REACTOR PARAMETRIC STUDY... 

The reactor used for this study was the horizontal atmospheric-pressure hot-wall reactor (reactor A in Fig. 6.11). The susceptor accommodated three substrates side by side at an angle of 15.5 ° above horizontal. The leading edge of the film experiences a more reactant-rich gas stream and is closer to the... 

Atmospheric Pressure Hot-Wall Reactor Parametric Study 181... 

Typical Reactor Design. Table 5.1 lists typical CVD production reactors which include cold-wall and hot-wall reactors operating at low or atmospheric pressures. The decision to use a given system should be made after giving due consideration to all the factors of cost, efficiency, production rate, ease of operation, and quality. 

Closely related to the superheating effect under atmospheric pressure are wall effects, more specifically the elimination of wall effects caused by inverted temperature gradients (Fig. 2.6). With microwave heating, the surface of the wall is generally not heated since the energy is dissipated inside the bulk liquid. Therefore, the temperature at the inner surface of the reactor wall is lower than that of the bulk liquid. It can be assumed that while in a conventional oil-bath experiment (hot vessel surface, Fig. 2.6) temperature-sensitive species, for example catalysts, may decompose at the hot reactor surface (wall effects), the elimination of such a hot surface will increase the lifetime of the catalyst and therefore will lead to better conversions in a microwave-heated as compared to a conventionally heated process. 

Figure 6.11. Schematic of two of the reactors used (a) atmospheric pressure horizontal hot-wall reactor (Reactor A) and (b) vertical cold-wall reactor (Reactor B).

Another example of a cold-wall reactor is shown in Fig. 5.9. It uses a hot plate and a conveyor belt for continuous operation at atmospheric pressure. Preheating and cooling zones reduce the possibility of thermal shock. The system is used extensively for high-volume production of silicon-dioxide coatings for semiconductor passivation and interlayer dielectrics. 

Dimensionless Quantities and Reactor Types. Transport phenomena in CVD reactors can be described in terms of two broad groups (1) hot-wall, low-pressure reactors and (2) cold-wall, reduced- and atmospheric-pressure reactors. 

Numerous modeling studies of CVD reactors have been made and are summarized in recent review papers (I, 212). Table 3 in reference 212 lists major examples of CVD models up to mid-1986. Therefore, rather than giving an exhaustive list of previous work, Table V presents a summary of the major modeling approaches and forms the basis for the ensuing discussion, which is most appropriately handled in terms of two groups (1) hot-wall LPCVD systems and (2) cold-wall, near-atmospheric-pressure reactors. In LPCVD reactors, diffusion and surface reaction effects dominate, whereas in cold-wall reactors operated at near-atmospheric pressures, fluid flow and gas-phase reactions are important in predicting performance, as discussed earlier in relation to transport phenomena. 

The hot leg pipe outflow stops when the water level in the vessel has dropped below the hot leg nozzle, and pressure equilibrium between the containment and the reactor vessel is established. The sdphon breaker arrangement provides "containment" pressure also on the inside of the cold leg nozzle, and the large outflow from the reactor system stops - all by itself The core is cooled by reactor pool water in natural circulation, and the decay heat is absorbed in the pool. The pressure in the containment attains a peak of about 270 kPa after about 1 minute, and then decreases due to steam condensation on containment walls and structures. In about 2 hours, it is down to slightly above atmospheric pressure again. 

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