Growth function reactor

We require two differential equations to define the time course of changes in the nutrient concentration Cg(r) and the number of organisms N(t) in the reactor. The exponential growth function is modified by its dependence on the nutrient concentration and the removal of organisms... 

Chemical vapor deposition (CVD) of carbon from propane is the main reaction in the fabrication of the C/C composites [1,2] and the C-SiC functionally graded material [3,4,5]. The carbon deposition rate from propane is high compared with those from other aliphatic hydrocarbons [4]. Propane is rapidly decomposed in the gas phase and various hydrocarbons are formed independently of the film growth in the CVD reactor. The propane concentration distribution is determined by the gas-phase kinetics. The gas-phase reaction model, in addition to the film growth reaction model, is required for the numerical simulation of the CVD reactor for designing and controlling purposes. Therefore, a compact gas-phase reaction model is preferred. The authors proposed the procedure to reduce an elementary reaction model consisting of hundreds of reactions to a compact model objectively [6]. In this study, the procedure is applied to propane pyrolysis for carbon CVD and a compact gas-phase reaction model is built by the proposed procedure and the kinetic parameters are determined from the experimental results. 

Molecular weight distribution function for the case where the length of the growth stage is short compared to the residence time in reactor. (Reprinted with permission from Chemical Reactor Theory, by K. G. Denbigh and J. C. R. Turner. Copyright 1971 by Cambridge University Press.)... 

The stability of C60 and C70 solutions in vegetable oils has been examined also towards the action of UV light. A C60 solution in linseed oil has been irradiated in a quartz reactor with UV light from a 12 W low-pressure Hg lamp having its main emission at 254 nm under N2. In less than 1 hour irradiation, all the visible part of the electronic spectrum of C60 with bands at about 530 and 600 nm have been bleached. Simultaneously, a growth in absorption intensity as function of the irradiation time has been observed at about 410nm. 

Fig. 2 Reported growth rate of tin oxide, prepared from (Ctf3)4Sn + O2, as a function of temperature. Borman et al. [39] used a hot wall reactor with various diameters shown in the legend, [TMT] = 99-390 ppm. Ghostagore [32,33] used a horizontal cold wall reactor with [TMT] = 117-310 ppm. Chow et al. [54] used a stagnation-point flow reactor, and Vetrone et al. [55] a horizontal hot-wall reactor with a tilted substrate...

An interesting class of exact self-similar solutions (H2) can be deduced for the case where the newly formed phase density is a function of temperature only. The method involves a transformation to Lagrangian coordinates, based upon the principle of conservation of mass within the new phase. A similarity variable akin to that employed by Zener (Z2) is then introduced which immobilizes the moving boundary in the transformed space. A particular case which has been studied in detail is that of a column of liquid, initially at the saturation temperature T , in contact with a flat, horizontal plate whose temperature is suddenly increased to a large value, Tw T . Suppose that the density of nucleation sites is so great that individual bubbles coalesce immediately upon formation into a continuous vapor film of uniform thickness, which increases with time. Eventually the liquid-vapor interface becomes severely distorted, in part due to Taylor instability but the vapor film growth, before such effects become important, can be treated as a one-dimensional problem. This problem is closely related to reactor safety problems associated with fast power transients. The assumptions made are ... 

As most organometallic precursors, V(NEt2)4 pyrolysis involves a complicated mechanism highly dependent on the experimental conditions. For this reason, the CVD experiments were conducted at reduced pressure (Table 15.4) in order to improve the diffusivity of the species, reduce their interactions in the gas phase and disfavor subsequent reactions. Two CVD units (hot-wall and cold-wall) of the same geometry were used in this study. Since the reactions in the gas phase are likely to be different in these two types of reactors, we could use them to study the influence of the gas phase chemistry on the growth rate. The composition of the deposits was studied as a function of the substrate temperature under He gas and as a function of the nature of the carrier gas when H2 and NH3 were added in various amounts. 

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