Spherical reaction vessels

Lewis and von Elbe have ignited CO/O2 mixtures in the centre of spherical reaction vessels, and have obtained data on the rate of propagation of the flame and the rate of pressure change in the vessel. From such results the burning velocity S, can be calculated [4], according to the thin flame approximation, from eqn. (120),... 

Thus, the heat release rate is proportional to the measured temperature excess. The heat release rate and its dependence on conditions may be the fundamental information required for the interpretation of many combustion phenomena, but once again the heat transfer coefficient must be evaluated. Heat transfer coefficients for low-pressure gases in closed, stirred, spherical reaction vessels were measured by Gray and co-workers [40-42]. A simple quantitative relationship of the rate of reactant consumption to the temperature excess requires that the overall exothermicity does not vary with reaction conditions. As is implicit in Chapter 1 from the variations in reaction stoichiometry, and discussed further in Section 6.5, this is certainly not the case during alkane oxidation over the temperature range 500-900 K. 

The reaction vessel is situated inside a metal of high themial conductivity having a cylindrical, spherical, or other shape which serves as the calorimetric medium. Silver is the most suitable material because of its high themial conductivity, but copper is most frequently used. 

Irradiation Procedure. Reaction mixtures were prepared at room temperature by transferring desired quantities of reactants from their storage bulbs to the reaction vessel, a 500-cc. spherical borosilicate glass flask attached to the vacuum line by a section of glass capillary tubing and a 4-mm. bore threaded glass valve with a Teflon plug (Fischer and Porter 795-609). Prior to each experiment this vessel was baked under vacuum at 500°C. for 12 or more hours. 

Traditional Apparatus. The above reference need only be expanded to Include the common use of cylindrical culture vessels (1), in place of the spherical reaction flasks, for shear sensitive materials and simple boiling water type baths (2) as their heating medium. 

With due regard to the lateral variations in composition which can arise as a consequence of source geometry and positioning (discussed in Section II), it is vise to analyze the alloy film at a number of representative points. For example, if a catalytic reaction was carried out over an alloy film deposited inside a spherical vessel maintained at a constant temperature over its entire area, then the mean alloy composition (and the uniformity of composition) is required. A convenient procedure is to cut glass reaction vessels carefully into pieces at the end of the experiment and to determine the composition by X-ray fluorescence analysis of a number of representative pieces. Compositions of Pd-Ag alloy films (40) determined at 12 representative parts of a spherical vessel from the intensities of the AgK 12 and PdKau fluorescent X-ray emissions are shown in Table V mean compositions are listed in the first column. (The Pd and Ag sources were separate short concentric spirals.) In other applications of evaporated alloy films to adsorption and catalytic studies, as good or better uniformity of composition was achieved. Analyses of five sections of a cylindrical... 

An alternative to the use of small spherical phials, which often has advantages in terms of the flexibility of the apparatus, is the use of calibrated vessels or ampoules with break-seals. They consist usually of a tube 3-6 mm i.d. and 20-70 mm long with a calibration mark and carrying a fragile glass membrane which can be broken when desired, so as to admit the contents of the ampoule to a mixing vessel or reaction vessel. The construction of different types of magnetic break-seals has been described in Section 2.2.4.4. 

Reaction vessel Unspecified 500 ml. spherical borosilicate glass ... 

At temperatures above 30°C, the rate increased slightly with temperature in a cylindrical reaction vessel but decreased slightly in a spherical vessel. A sharp increase in rate was noted as the temperature was decreased from 30°C. In the absence of water vapor or nitrogen dioxide a distinct induction period was observed, during which products were formed very slowly. The apparent rate increased slowly, and reached a maximum one-fourth to one-third of the way to reaction completion. The results quoted below were obtained near the start of the reaction but after the apparent induction period. The autocatalytic effect of nitrogen dioxide had been observed earlier in aqueous solutions. The reaction was found to obey the following rate law reasonably well. 

Emulsion polymerization requires the use of free radical initiators, fluorinated surfactants, and often chain transfer agents. The polymer isolated from the reaction vessel consists of agglomerated spherical particles ranging in diameter from 0.2 to 0.5 jm.56 It is then dried and supplied as a free-flowing powder or as pellets, depending on the intended use. If very pure PVDF is required, the polymer is rinsed before the final drying to eliminate any impurities such as residual initiator and surfactants.57... 

Fauskes Associates Inc. developed the RSST as an inexpensive screening tool [15,16], The RSST (Figures 12-14 and 12-15) consists of a spherical glass reaction vessel and immersion heater (optional),... 

Fig. 34. Propane-oxygen. Molar ratio 1 1 stirred spherical pyrex reaction vessel, volume 1000 cm. (From ref. 196.)...

Molar ratio 3 4 spherical pyrex reaction vessel, volume... 

The reaction of pentaborane with O2 below the first explosion limit in spherical Pyrex vessels was investigated by Price °. Blue light is emitted which increases in intensity by raising [B5H9], but decreases in intensity with an enhancement of [O2]. The first explosion limit can be expressed by... 

Reaction vessels The inside wall is usually used as the support for the deposit. The vessels, which are made of quartz or glass, are of two common types spherical flasks for adsorption measurements [1, 29] and cylinders, which are especially suited for... 

Oztme from an electrogenerator and the atmo.spheric sample are drawn eontinuously into a reaction vessel, where the luminescence radiation is monitored by a photomultiplier tube. A linear response is reported for nitrogen monoxide concentrations of 1 ppb to 10,000 ppm. Chemiluminescence has become the predominant method for monitoring the concentration of... 

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