[en] A simple algorithm for the geometrical optimization of the TD columns, with the application to the separation of ³⁶Ar was elaborated. (author)

[en] Thermal diffusion transport coefficients were measured for the ³⁶Ar-⁴⁰Ar system in a hot wire column. These coefficients were evaluated from both static and flow separation data. Some performances of the column with those of other columns cited in the literature are compared. (author)

[en] For a given product concentration, choice of the cascade structure is presented. For the cascade, having the minimum number of columns for the desired production, the operation curves and other characteristics are calculated. (author)

No abstract available

[en] Separation of ⁷⁸Kr and ⁸⁶Kr isotopes in a hot wire thermal diffusion (TD) column is presented. The transport coefficients were determined from both static and flow separation data. Finally, some performances of this column are compared with those of other columns cited in the literature. (author)

[en] The results of calculations of the transport coefficients, H and K, for a prototype concentric tube thermal diffusion column, operated with methane as progress gas, are presented. The variation of the separation factors at equilibrium, versus operating gas pressure, is presented graphically for various molecular models. The experimental separation factors for various pressures were found to be consistent with those calculated from the inverse power repulsion model and the Lennard-Jones (12,6) model. A description is also given of some theoretical and practical aspects of a seven-stage thermal diffusion cascade comprising 18+1 thermal diffusion columns of the concentric tube type. This system has been constructed and successfully operated and produces an enrichment of methane at 20% ¹³CH₄ by a continuous process. (author)

[en] The behaviour of a thermal diffusion system for multicomponent isotope separation in transient and steady state regimes is presented. The steady state distribution of the isotopic concentrations along the thermal diffusion system and the pressure dependence of the partial separation factors in the case of the krypton isotopes are computed. The optimization of the partial separation factors versus geometrical parameters is also given. (author)

[en] The structure of the ZnO-Cr₂O₃ system with variable Cr/Zn ratio was studied in the range 0.1< Cr/Zn<1.8. We report the existence of two crystalline phases, one with spinel structure, the other with NaCl structure, depending on the degree of reduction of the chromium ion. The existence of the spinel-like structure in the samples with Cr/Zn ratios less than 2.0 is explained by the presence of high valence states of the chromium ions. (author)

[en] Straw is a non-hazardous by-product of crop plants processing. Currently, it represent one of the most important biomass resource. The huge quantities of straw annually produced generate big problems in what concerns their disposal. The traditional field burning is no longer accepted, so another disposal solutions must be found and recycling is the most attractive. The paper refers to such a solution consisting in the conversion of the straw energy potential into electricity in a power plant based on an air turbine. This power system it is in fact an external combustion engine, derived from a gas turbine engine and operating with air as working fluid instead of combustion gases. In order to make possible the use of straw as fuel, the conventional combustion chamber is substituted by a hot air generator. Schematic of this power system and the results of its energetic analysis are presented in the paper. There are analysed the main performance indicators, namely thermal efficiency, output power, fuel consumption and specific fuel consumption. The results of the study indicate the analysed power system as an interesting solution for straw recycling. (paper)