Radial Diffusion and Penetration of Gas Molecules and Aerosol Particles through Laminar Flow Reactors, Denuders, and Sampling Tubes

Flow reactors, denuders, and sampling tubes are essential tools for many applications in analytical and physical chemistry and engineering. We derive a new method for determining radial diffusion effects and the penetration or transmission of gas molecules and aerosol particles through cylindrical tubes under laminar flow conditions using explicit analytical equations. In contrast to the traditional Brown method [Brown, R. L. J. Res. Natl. Bur. Stand. (U. S.) 1978, 83, 1-8] and CKD method (Cooney, D. O.; Kim, S. S.; Davis, E. J. Chem. Eng. Sci. 1974, 29, 1731-1738), the new approximation developed in this study (known as the KPS method) does not require interpolation or numerical techniques. The KPS method agrees well with the CKD method under all experimental conditions and also with the Brown method at low Sherwood numbers. At high Sherwood numbers corresponding to high uptake on the wall, flow entry effects become relevant and are considered in the KPS and CKD methods but not in the Brown method. The practical applicability of the KPS method is demonstrated by analysis of measurement data from experimental studies of rapid OH, intermediate NO3, and slow O3 uptake on various organic substrates. The KPS method also allows determination of the penetration of aerosol particles through a tube, using a single equation to cover both the limiting cases of high and low deposition described by Gormley and Kennedy ( Proc. R. Ir. Acad., Sect. A. 1949, 52A, 163-169). We demonstrate that the treatment of gas and particle diffusion converges in the KPS method, thus facilitating prediction of diffusional loss and penetration of gases and particles, analysis of chemical kinetics data, and design of fluid reactors, denuders, and sampling lines

System analysis of process of high-temperature thermomechanical treatment for blanks of hollow track pins

The process of high-temperature thermomechanical treatment with deformation by screw compression for hollow products has been developed. It is considered as a technical system that represents the set of functional relations between the elements such as: the modes of high-temperature thermomechanical treatment with deformation by screw compression, the geometry fidelity, the quality of working surfaces, the mechanical properties of the material, the operational life of part. Thus a connection is made between elementary x-qualities and performance properties.</jats:p

Hardening of track's pins of tracked machines with screw compression during the high-temperature thermomechanical processing

The stress-strain state of metal in deformation zone under the screw compression is considered using a mathematical model of process. This model allows to determine the limiting tangential stresses in a workpiece at the exit of deformation zone, which do not lead to the destruction provided by twist in the process of deformation.</jats:p

Influence of residual stresses on the precision of crawler tracks’ hollow fingers under high-temperature thermomechanical treatment with deformation by screw cogging

Residual stresses formed under screw cogging deformation in the high-temperature thermomechanical treatment mode were considered. They facilitate the increase of hot-rolled metal pipe precision up to precision level of cold-calibrated rolled metal by outside diameter.</jats:p

Mathematical modeling of thermal state of hollow track link pins’ workpieces

Mathematical model and numerical calculation results for the thermal state of cylindrical hollow track link pins’ workpiece are given. Numerical calculation results of heat exchange parameters depending on geometry, thermophysical properties and processing duration are analyzed.</jats:p

Forecasting the durability of hollow shafts and axles of agricultural machinery products

The issues of increasing durability in the development of technologies for strengthening the critical parts of agricultural machinery products are considered. The conducted experiments and calculations show that the use of hollow axes, shafts and other hollow products gives a great technical and economic effect, reduces the consumption of metal, facilitates the weight of equipment and ensures its high performance. The technique of prediction of the durability of parts with thermomechanical processing and deformation by screw compression from hot-rolled especially thick-walled pipes is presented, their bench and operational tests have been carried out, showing that hardened hollow parts not only do not concede, and sometimes exceed continuous durability. Optimization of the processing of parts, taking into account the stated results of theoretical and experimental studies, makes it possible to increase their efficiency. Considering that it is necessary to deal with multifactorial dependencies, it is advisable to automate their solution. Algorithms and programs for computer technology have been developed for a number of technological processes, successfully used both for automating the design of technological processes and for automating production itself. With the use of thermomechanical processing and deformation by screw compression, a fivefold increase in durability with asymmetric sign-constant bending is achieved on some products (track fingers of caterpillar machines). Thus, it becomes evident that the use of hollow axes, shafts and other hollow parts in agricultural machinery construction is much more widespread than at present, given the very important property of these hollow parts, that they are less sensitive to stress concentration under cyclic loads, especially if hardening is performed by high-temperature thermomechanical processing. It is recommended to use this unique treatment of responsible and highly loaded machine parts for a wide range of applications.</jats:p

Equipment for high-temperature thermomechanical processing of long-measuring axially symmetrical machine parts

The process equipment complex for high-temperature thermomechanical processing with deformation by the screw reduce is considered. It permits to obtain a regular reinforced profile for manufacturing of multi-diameter (hollow and entire) shafts and axes.</jats:p

Comparative analysis of methods for improving the quality of hardened pipe and bar stock for agricultural machinery parts

The problem of obtaining a high-quality surface is acute in thermal, chemical-thermal and thermomechanical processing of products of rolling production. But, due to the fact that many metallurgical plants are insufficiently equipped with cleaning tools for these types of processing, the required surface quality of metal products is not ensured. Operations related to the removal of defects in the surface of rolled products employ from 30 to 60% of the workers in rolling shops. The need for cleaning leads to a rupture of the production flow, since the metal must be pre-cooled for inspection and cleaning of defects. As a result, the total cost of cleaning is 2 - 3 times higher than the cost of performing the main technological operations - heating and deformation of the metal. In this regard, the combined methods of hot rolling with simultaneous hardening and elimination of surface defects are of particular interest, which gives significant energy savings and excludes etching operations in solutions of sulfuric and hydrochloric acids. The paper considers new methods for stripping rolled stock before deformation in the high-temperature thermomechanical treatment (HTMT) mode of cylindrical hot-rolled solid and hollow billets with screw compression (SC) deformation, combining, along with a high-performance method of shaping and strengthening of rolled products, environmentally friendly (acid-free) methods of surface cleaning, as well as methods of removing surface layer defects combined with mechanical processing. At the same time, simultaneously with cleaning the surface and increasing the accuracy of rolled products, the structure of the surface layer is formed by the mechanism of phase transformations during thermomechanical processing. The type of fracture changes at low-temperature destruction from brittle to ductile. It should also be noted, that there is the need for further development of such well-proven cleaning methods as blade and waterjet processing, which allow, when cleaning rolled products from any steel grades from scale, to implement the most reliable cleaning system, ensure effective removal of surface and deeper defects, increase yield, reduce energy consumption and fit well into the continuous rolling mill line. According to recent studies, waterjet treatment increases the fatigue life of hollow cylindrical parts by up to 15%.</jats:p

Determination of optimality criteria in the development of hardening technologies

The article considers the optimality criteria in the development of hardening technologies for critical parts of engineering products. It also presents a forecasting method for product quality indices in the process of high-temperature thermomechanical treatment with deformation by screw compression of hot-rolled heavy-walled pipes.</jats:p

Conversion technology of track pin production

The expediency of prospective methods of forming surface defects removal combined with progressive high-temperature thermomechanical treatment with screw compression deformation is shown.</jats:p