Energy balance secondary reactions

The model is based on the schematic representation of the commercial reactor shown in Figure le. The wafers are supported concentrically and perpendicular to the flow direction within the tube. The heats of reaction associated with the deposition reactions are small because of the low growth rates obtained with LPCVD ( 2 A/s). Furthermore, at high temperatures (1000 K) and low pressures (100 Pa), radiation is the dominant heat-transfer mechanism. Therefore, temperature differences between wafers and the furnace wall will be small. This small temperature difference eliminates the need for an energy balance. Moreover, buoyancy-driven secondary flows are unlikely. In fact, because of the rapid diffusion, the details of the flow field... 

Pumping requirements are roughly proportional to the number of modules, i.e., they are a function of electrode area. As we have shown in connection with the transformer/rectifier, Wisa, function of S, i, E a, Ec, Vjy, and R. The relative rates at which the primary and secondary reactions proceed varies with 1 The process variables which affect W, E and r will, by virtue of the energy balance, also affect Q, which leads us to Eq. (6.65). Since the capital cost of the coolers Q and the annual cost of cooling water are directly related to Q, they will also be functionally dependent upon these variables. 

Fermentation, the process that generates hydrogen, is a balanced oxidation-reduction reaction, in which different portions of a single substrate are oxidized and reduced, yielding energy. F ermentation yields substantially less energy per unit of substrate compared to oxidation reactions which utilize an external electron acceptor thus, fermentation generally occurs when these external electron acceptors are not available. Bacterial fermentation which can be important in anaerobic aquifers includes primary and secondary fermentation. 

The metathesis reactions of acyclic olefins, such as propene, reaction (3), but-2-ene, reaction (2), and alk-2-enes generally, tend to be fairly evenly balanced at equilibrium. However, where reactants or products have cis and trans isomers, the lawer-energy trans isomer tends to predominate at equilibrium. But with some catalysts, cis reactants initially yield mainly cis products and the equilibration between cis and trans isomers occurs by a relatively slow secondary metathesis reaction [52]. For a proper understanding of the mechanism of these reactions it is essential to follow the cis/trans ratio of both reactants and products with time. A well studied case is the metathesis of 4-methyl-cw-pent-2-ene and its trans isomer catalyzed by WClg/Bu4Sn/Et20 [53, 54]. 

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