Influence of the Luminous Gas Phase into Butane Plasma Polymerization in a Closed Reactor System

High Energy Chemistry - This study investigated the plasma polymerization process of butane in a closed radio frequency plasma reactor system. Optical emission spectra of the luminous gas phase...     

Stoichiometric Oxidation of Hyaluronic Acid by 2,2,6,6-Tetramethylpiperidinium-1-Oxoammonium Tribromide

Chemistry of Natural Compounds -     

Novel superabsorbent polymer composites based on α-cellulose and modified zeolite: synthesis,characterization, water absorbency and water retention capacity

Cellulose - Most superabsorbent polymers (SAPs) are prepared based on synthetic polymers (from petroleum resources), making them costly, nondegradable, and not ecofriendly. To overcome these...     

The influence of radiation on the temperature profile of an induced discharge in argon at atmospheric pressure

This study presents a quantitative evaluation of the influence of radiation upon the parameters of a long induced discharge in argon at atmospheric pressure. Radiation heat transfer in the optically transparent tin plasma layers with thickness of the order of several centimeters) and reabsorption spectral intervals is examined. Experimental error produced by inaccurate knowledge of the transfer and optical characteristics of the plasma is evaluated. The effect of convection on radial temperature profile is evaluated.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiztki, No. 6, pp. 35–43, November–December, 1971.     

Convective heat transfer and temperature stratification in a sphere completely filled with a liquid,with a given heat flux

A number of articles have been devoted to the theoretical and experimental investigation of natural convection in spherical vessels completely filled with a liquid [1–6]. Analytical solutions are known, obtained by the expansion of the sought function in series in powers of the Rayleigh number (see, for example, [1]), valid for very small values of this number. A numerical solution of the nonlinear Boussinesq equations can be used to obtain solutions with larger Rayleigh numbers, but the existing data for spherical regions [2, 3] embrace a relatively narrow range of Rayleigh numbers. The experimental data with a given heat flux, published in [4–6], were obtained with relatively large Rayleigh numbers (Ra*=10⁹?10¹¹) and Prandtl numbers (P= 3?1500). Data on the characteristics of convection in spherical vessels are still not very numerous and, in a number of cases, contradictory. This relates, in particular, to the boundaries of unsteady-state conditions. The present article, continuing [7–9], expounds a method and gives the results of a calculation of convection in a sphere with a thinwalled shell, in a range of Rayleigh and Fourier numbers embracing the principal conditions of unsteady-state laminar convection with a given heat flux.     

Methods and correlations for the prediction of quenching rates on hot surfaces

A substantial quantity of experimental data on rewetting, much of which has not been previously reported, is analysed using the results of calculations of the two-dimensional conduction processes taking place in the walls of tubes, which have been used to simulate the cladding of nuclear fuel elements. Correlations giving the quenching heat-transfer coefficient and sputtering temperature are proposed as a result of the analysis. These correlations may be combined with the previously reported conduction analysis to predict rewetting rates under a wide range of conditions. The new data include falling film rewetting rates measured for a range of system pressures (1–15 bars), initial wall temperatures (200–650°C), coolant mass flowrates (3–50 g sec^?1) and subcoolings (0–90°C). Measurements have also been made of rewetting rates by bottom flooding of both saturated and subcooled water at atmospheric pressure.     

Uniqueness and stability of steady states of continuous chemical reactors

We examine the uniqueness and stability of the solutions to the problem of steady-state operation of a continuous chemical reactor in which longitudinal diffusion and heat conduction are taken into account. We investigate an adiabatic reactor in which the concentration and temperature distributions are similar (the thermal diffusivity and diffusion coeffecient are equal) and an isothermic reactor. These two cases are considered together because the mathematical formulations of the problem are equivalent.The question of the existence and number of steady states was analyzed in [1, 2], where references were made to earlier investigations. The results obtained in [1, 2] are now extended. The stability of the steady states is investigated by the small-perturbation method.     

Interaction of a turbulent wake with the outer flow

The integral methods of boundary-layer theory are used to examine the interaction of a turbulent wake with the outer flow for the example of planar flow.In contrast with the known Crocco-Lees theory [1], the turbulent layer in the gas is described with the aid of an appropriate family of velocity profiles rather than by means of a Dorodnitsyn-type transformation of the incompressible turbulent layer. The selection of the simplest among the possible systems of first order interaction equations is justified; this system reduces to a single differential equation and an estimate is given of the influence of the arbitrariness in the equation selection on the final results.The hydrodynamic meaning of the singular and nonsingular integral curves and the singular point of the interaction equation is clarified on the basis of an examination of the interaction of compression and rarefaction waves in the outer supersonic stream with the wake. The effect of blowing (suction) and the initial boundary layer on the base pressure and the supersonic interaction flow as a whole is examined on the basis of the integral conditions for the splicing of the interaction flow with the isobaric mixing flow behind the corner. It is shown that, with proper selection of the single constant in the turbulent viscosity formula, the computational results are in satisfactory agreement with experiment.In conclusion, the authors wish to thank G. G. Chernyi for helpful discussions of the study, and L. V. Kapranova and Z. A. Donskova for assistance in the calculations.     

Viscosity of the liquid phase in a dispersion

The motion of a dispersion (continuous medium and particles) may be described [1] via the equations ot conservation of matter and momentum for the two phases separately. Here it is necessary to know how the viscosity, pressure in the solid, and other quantities vary with the parameters of the motion. This difficulty occurs even for the very simple model where the internal stresses in the dispersed phase are taken as zero, as there is then an uncertainty as to the viscosity of the medium, which is not a material constant and is dependent on the concentration. There is also uncertainty as to the forces of interaction between the phases. There are numerous empirical relationships for these forces, and also a theoretical one [2]. Here an analogous method is applied to derive an expression for the viscosity of the liquid. This viscosity applies to a liquid filtering through a porous medium in the particular case where the concentration is such as to produce close packing of the solid particles. The result corresponds to standard formulas in the case of low concentrations.     

The acceleration of electrons in a boundary layer

The effect of the redistribution of energy between ion and electron components for the motion of a plasma in a nonuniform magnetic field is considered on the example of a flat model of an equilibrium boundary layer between a rarefied plasma and a magnetic field in the relativistic invariant form. The relativistic and polarization corrections to the classical theory are found. Results are given for a numerical solution of the problem.