Atmospheric pressure investigations

The reaction is significantly exothermic with a heat of reaction of about 40 kcalmol . This energy will produce a sufficiently high temperature to melt the product and will allow the influence of thermochemical factors to be investigated. The temperature required to initiate the Ni-Al reaction at atmospheric pressure is about 660 °C. This reaction temperature threshold will be encountered in the shock processing, but it should be recognized that the conventional synthesis process is preceded by melting of the aluminum. At the pressure of the shock compression, the melt temperature of the aluminum will be approximately doubled to a value above the mean-bulk tempera-... 

Beyer (B8) has recently reported experimental data obtained in small test motors under atmospheric and altitude conditions. At atmospheric pressure, his results showed the observed ignition delay to be a function of the delivery rate, as shown in Fig. 10. Additional data obtained in small test motors by Fullman and Nielsen (F6) are shown for comparison. These latter investigators conducted studies on the effects of various injectors, with delivery from both the head end and the aft end. Their results indicate that the hollow-cone injector is the most efficient. This subject has been treated in more detail by Miller (M7). 

A considerable amount of research has been conducted on the decomposition and deflagration of ammonium perchlorate with and without additives. The normal thermal decomposition of pure ammonium perchlorate involves, simultaneously, an endothermic dissociative sublimation of the mosaic crystals to gaseous perchloric acid and ammonia and an exothermic solid-phase decomposition of the intermosaic material. Although not much is presently known about the nature of the solid-phase reactions, investigations at subatmospheric and atmospheric pressures have provided some information on possible mechanisms. When ammonium perchlorate is heated, there are three competing reactions which can be defined (1) the low-temperature reaction, (2) the high-temperature reaction, and (3) sublimation (B9). 

PA-6,6 is made from the relatively expensive materials hexamethylene diamine and adipic acid. An alternative synthesis of PA-6,6 from adiponitrile and hexamethylene diamine utilizing water is under investigation.16 PA-6 can be synthesized in a continuous process at atmospheric pressure, but reaction times are very long as the ring-opening initiation step is particularly slow. The reaction time can be shortened considerably by carrying out prepolymerization in the presence of excess water at pressure however, this makes the continuous polymerization process more complex. Copolymers with amide units of uniform length (diamides) are relatively new the diamide units are able to crystallize easily and have a thermally stable crystalline structure. 

As already noted the strength of chemisorptive bonds can be varied in situ via electrochemical promotion. This is the essence of the NEMCA effect. Following initial studies of oxygen chemisorption on Ag at atmospheric pressure, using isothermal titration, which showed that negative potentials causes up to a six-fold decrease in the rate of 02 desorption,11 temperature programmed desorption (TPD) was first used to investigate NEMCA.29... 

The reaction was investigated under atmospheric pressure and at temperatures 500°C to 600°C, where the only product was CO, as Pd, contrary to Rh, does not adsorb C02 dissociatively.59 This difference in reaction pathway is also reflected in the NEMCA behaviour of the system, since in the present case CO formation is enhanced (by up to 600%) not only with decreasing catalyst potential and work function, but also enhanced, although to a minor extent, via catalyst potential increase (Fig. 8.56). Enhancement factor A values up to 150 were measured. The reaction exhibits typical inverted volcano behaviour, which is characteristic of the weak adsorption of the reactants at the elevated temperature of this investigation, and thus of promotional rule G4. 

Pressure drop and heat transfer in a single-phase incompressible flow. According to conventional theory, continuum-based models for channels should apply as long as the Knudsen number is lower than 0.01. For air at atmospheric pressure, Kn is typically lower than 0.01 for channels with hydraulic diameters greater than 7 pm. From descriptions of much research, it is clear that there is a great amount of variation in the results that have been obtained. It was not clear whether the differences between measured and predicted values were due to determined phenomenon or due to errors and uncertainties in the reported data. The reasons why some experimental investigations of micro-channel flow and heat transfer have discrepancies between standard models and measurements will be discussed in the next chapters. 

Figure 5.1 Pesticides included in the systematic investigations on APCI-MS signal response dependence on eluent flow rate the parameter IsTow represents the distribution coefficient of the pesticide between n-octanol and water. Reprinted from J. Chromatogr, A, 937, Asperger, A., Efer, 1., Koal, T. and Engewald, W., On the signal response of various pesticides in electrospray and atmospheric pressure chemical ionization depending on the flow rate of eluent applied in liquid chromatography-mass spectrometry , 65-72, Copyright (2001), with permission from Elsevier Science.

Subsequently, the problem was investigated by Karpov and Severin [6]. They used closed vessels with a diameter of 10cm and 10, 5, and 2.5cm width, initially at atmospheric pressure. The vessels were filled with different lean hydrogen and methane/air mixtures and rotational speeds in the range of 130-4201/s were employed. They also included data from the study of Babkin et al. [3] in their analysis. Unfortunately, they did not observe the flame itself and measured only the pressure rise in the vessel, which was compared with pressure development in the vessel without rotahon, to draw a conclusion with respect to flame speeds and quenching. 

Major emphasis in studies of N-nitroso compounds in foods has been placed upon volatile nitrosamines, in part because these compounds are relatively easy to isolate from complex matrices by virtue of their volatility. Procedures utilizing atmospheric pressure or vacuum distillation have been used by most investigators, with variations of the method of Fine e al. (2) being among the most popular. This procedure employs vacuum distillation of a mineral oil suspension of the sample with optional addition of water to improve nitrosamine recovery from low moisture content samples (6) The usual approach to prevention of nitrosamine formation during analysis involves adding sulfamic acid or ascorbate to destroy residual nitrite at an early stage of sample preparation. 

Gauthier P-J, Condomines M, Hammouda T (1999) An experimental investigation of radon diffusion in an anhydrous andesitic melt at atmospheric pressure Implications for radon degassing from empting magmas. Geochim Cosmochim Acta 63 645-656... 

Ivey, H. J., and D. J. Morris, 1965, The Effect of Test Section Parameters on Saturation Pool Boiling Burnout at Atmospheric Pressure, AIChE Chem. Eng. Prog. Symp. Ser. 67(60) 157—166. (2) Jacket, H. S., J. D. Roarty, and J. E. Zerbe, 1958, Investigation of Burnout Heat Flux in Rectangular Channels at 2000 psia, Trans. ASME, J. Heat Transfer 50 391. (5)... 

Both catalytic reactions were investigated in the gas phase under atmospheric pressure using a glass fixed bed micro-reactor Prior to the reaction given amount of the catalyst (fraction 0.5-0.71 mm) was in situ activated at 500 °C for 2 h (N2 stream 40 ml min"1) In the case of toluene disproportionation the reaction temperature was 500 °C, WHSV 2-20 h"1, concentration of toluene in a stream was 18.5 mol%. Toluene alkylation was studied at the reaction temperature 250 °C. WHSV related to toluene was 10 h"1, concentration of toluene was 18.5 mol% and toluene to isopropyl alcohol molar ratio was 9.6. 

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