Application of Numerical Analysis for Physical and Chemical Combustion Processes in Design of Boiler Units

2015 ◽  
Vol 770 ◽  
pp. 365-370
Author(s):  
Andrey V. Gil ◽  
Alexander S. Zavorin ◽  
Elena S. Vorontsova ◽  
Gavriil A. Nizkodubov

It is common knowledge that theoretical approaches do not allow conducting the objective assessment of the reliability and efficiency of the boiler equipment operation, hence, application of numerical approaches is introduced in the paper. There is the urgent need to assess reliability and efficient operation of boilers at the design stage. The analysis of the temperature level, gas dynamics in the combustion chamber of the boiler and the conclusion about the reliability and efficiency of the designed boiler operation are based on the numerical research.

2018 ◽  
Vol 196 ◽  
pp. 01058 ◽  
Author(s):  
Marek Wyjadłowski ◽  
Irena Bagińska ◽  
Jakub Reiner

The modern recognition of subsoil with the use of CPTu static probes allows to obtain detailed information necessary for the designing. Registered basic two quantities, i.e. cone resistance qc and friction on the sleeve fs, often become direct data, which allow to estimate bearing capacity of the base and the side surface of the pile. Direct methods use similarity of the pile work and piezo-cone work during the examination. An important design stage is the appropriate development of measurement data prior to the commencement of the procedure of determining the pile bearing capacity. Algorithms generated on the basis of empirical experiments are often applied with the simultaneous use of test loads. The probabilistic approach is also significant, because it enables objective assessment of the reliability level of performed design calculations. This work contains an analysis of the impact on the estimated bearing capacity and reliability of a pile of variable random depth of the pile base. It also includes the determination of probabilities of obtaining the assumed safety index for the designed solution at random foundation depth.


2021 ◽  
Vol 6 (4) ◽  
pp. 267-276
Author(s):  
A. A. Khoreshok ◽  
A. V. Kudrevatykh ◽  
A. S. Ashcheulov ◽  
A. V. Vinidiktov ◽  
L. I. Kantovich

At present, Kuzbass coal strip mines pay great attention to improving quality performance of mining equipment operation, including reliability and durability of components and units. One of the ways of the performance improvement is decreasing number of unforeseen failures. To achieve this purpose a mine dump truck part diagnostics should be introduced into a maintenance service procedure. At the same time the process of diagnostics should not increase the machinery downtime, but effectively reveal a condition of motor-wheel gearboxes in the course of dump truck operation. The aim of the research is to increase the reliability and service life of motor-wheel gearboxes of large BelAZ dump trucks. Failure of a motor-wheel gearbox is a rare phenomenon, but the cost of a new gearbox can vary from 3.5 to 10 million rubles. That is why it is important to implement such methods of diagnostics, which allow revealing the condition of gearboxes in the shortest possible time and without disassembling corresponding units. Determination of the actual technical condition of motor-wheel gearboxes is possible by different methods: vibroacoustic; acoustic; thermal; physical and chemical analysis of spent operating materials. The studies showed that none of these methods can be used as a universal one. When justifying and selecting the most suitable method, different factors should be considered, including technological, or a combination of methods should be applied, which will reduce risks, but at the same time increase costs. It is necessary to develop a better diagnostic method based on the use of several methods simultaneously.


Author(s):  
Yaser Hamza Salman Al Khudiry

In this research, for the first time in Ukraine, a large volume of foreign scientific sources on public service advertising (PSA) was analyzed that allowed to make an assessment of the differences in theoretical approaches to the determination of the PSA and of the main research vectors of exploring this social and communication phenomenon; an attempt to expand its theoretical and methodological fundamentals was taken. The study is based on qualitative analysis of 122 scientific sources. The data was systematized and generalized. Descriptive, comparative and empirical-analytical methods were used to make an objective assessment of the subject. System method was applied to link each item to its role and place in the system. It is shown in the research that scientific approaches to the concept of PSA are ambiguous; they vary depending on historical, cultural, political and other factors. More than half a century American as well as European scientists have been attempting to explore the PSA as a separate subject; currently, the most actual trends in public service advertising development relate to its applicable aspects, its social communication techniques and efficiency. Constantly expanding geography of the research contemplates a tendency towards deeper understanding of the subject, thanks to the outcomes of implemented information campaigns. Special attention in the PSA research is dedicated to the psychological factors of influencing audience, the latest communication channels, and specifics of the content. Considering the international experience and historical factors, the conceptual apparatus of public service advertising was specified in this research, and the ways for improving further scientific studies of the PSA in Ukraine are proposed.


Author(s):  
A. G. Kyne ◽  
M. Pourkashanian ◽  
C. W. Wilson ◽  
A. Williams

As emission regulations become more stringent there is increasing interest in the formation of NO2 in combustion products where it is in higher concentration than if slowly formed from NO in the atmosphere. It is common knowledge that NO2 is significantly more toxic than NO. The chemistry of NO2 formation in combustion processes is simple in comparison to that of NO. Indeed, all NO2 is formed from oxidation of NO mainly by reaction with HO2 radicals with its conversion back to NO resulting from reactions involving O and H atoms. Since consumption and formation of NO2 always occur simultaneously, although with unbalanced kinetic rates leading to local super-equilibrium concentrations, parameters such as temperature, velocity and species concentrations fields can drastically affect the degree of conversion of NO to NO2 in combustion applications. It is not well known what these conditions are and in certain circumstances, such as aircraft engine reheat systems, the emission of NO2 is clearly visible under the form of brown fumes. A comprehensive numerical simulation was undertaken to investigate the NO-NO2 relationship in a counter-flow diffusion flame. The CHEMKIN II suite of software (Kee et al., 1989) in conjunction with the opposed diffusion flame code OPPDIF (Lutz et al, 1997) was run using the Gas Research Institute’s (GRI’s) methane reaction mechanism v.3.0. A number of different strain rates using boundary conditions typical in a gas turbine exhaust were investigated. A rate of production and sensitivity analysis was made in determining which reactions were important in the NO-NO2 conversion process.


2008 ◽  
Vol 43 (1) ◽  
pp. 41-67 ◽  
Author(s):  
Pelle G. Hansen

In his Convention (1969) David Lewis defined conventions as behavioural regularities instantiating proper coordination equilibria made salient by precedent and operational by this being common knowledge. While later proponents of game theoretical approaches in the study of convention have agreed on dropping Lewis’ eccentric ‘coordination’ requirement as well as that of common knowledge, they are confused as to whether conventions should be regarded as proper thereby precluding mixed equilibria. In this paper I argue that mixed equilibria may not be conventions, but also suggest that the reason for this reveals that though common knowledge is not necessary for a convention to operate, it may be utilized to identify the conventional aspect of a given practice.


2020 ◽  
Vol 220 ◽  
pp. 01093
Author(s):  
Artem Blinov ◽  
Nikolay Malastowski ◽  
Leonid Myagkov

Selective catalytic reduction systems are widely applied as a NOX emission control technology in modern onand off highway diesel engines. Considering the stringent limits of emission standards, they should ensure high rates of conversion efficiency. To achieve that at the design stage numerical modelling is used to optimize physical and chemical processes. New mathematical models and methods that can provide the reduction of calculation time and related costs keeping the acceptable level of prediction accuracy are desired. In this study a methodology for calculating SCR systems based on the use both of CFD models and simplified catalyst models are presented. The capabilities of the suggested numerical approach were demonstrated during the simulations of a SCR system where the influence of UWS injection angle on NOX reduction efficiency was investigated.


2020 ◽  
Vol 17 (36) ◽  
pp. 1061-1074
Author(s):  
Georgy Georgievich KLASNER ◽  
Alexandr Maximovich SPIRIDONOV

Nowadays, every farmer is faced with the task of providing their livestock with high-quality food that will contribute to their rapid growth and health. It is also common knowledge that large farms have more opportunities to implement their projects and put new technologies and gadgets into operation. The presented device makes it possible to obtain a product of processing soy grain into soy milk, soy cheese "tofu", soy protein base for preparing feed for farm animals and poultry in small farms. This article explains the experimental method for finding the optimal values of the speed of rotation of the movable disk, the temperature of the extractant, the gap between the movable and stationary disks of the shredder, and the ratio of the hydromodule. Optimal values are those that contribute to the maximum protein yield. Experimental factors: ambient temperature from 17°C to 22 °C, barometric pressure from 93325 PA to 96658 PA, relative humidity from 65% to 85%. Protein extraction in an emulsion is based on the physical and chemical properties of the diffusion of dissolved organic compounds, with water as the extractant. As a result, methods have been found for the effective production of protein from soy grains, which can increase the yield of the suspension to 24-28 Gr. This is the most productive way to produce protein for feed modification using this device.


Author(s):  
А.В. Сергеевичев ◽  
В.И. Онегин

Лакокрасочные покрытия используются в различных отраслях народного хозяйства. Удачно сочетая комплекс положительных свойств, присущих полимерным материалам, с декоративными и физико-механическими свойствами древесины и древесных материалов, покрытия позволяют успешно реализовать многочисленные задачи по формированию защитно-декоративных покрытий на современном этапе научно-технического прогресса. В связи с широким использованием лакокрасочных покрытий в технике интенсивно разрабатываются новые лакокрасочные материалы, методы нанесения и приемы образования покрытий, совершенствуются аппаратура и методы исследования, расширяется область применения. В настоящей статье, основу которой составляют результаты многочисленных работ в области физико-химических процессов, проходящих на границе раздела жидкость – подложка при образовании лакокрасочных покрытий, сделана попытка обобщить накопленные материалы за годы исследований, при этом стремились к объективной оценке имеющихся данных, что позволяет указать на необходимость дальнейшего развития научных представлений, лежащих в основе процессов образования покрытий. Авторы стремились вскрыть физико- химическую сущность процессов образования покрытий и показать многофактурность процесса формирования лакокрасочного покрытия. При этом в меньшей степени обращалось внимание на конкретность того или иного режима, а рассматриваются кинетические закономерности и тенденции процесса. Формирование лакокрасочных покрытий включает в себя сложный комплекс стадий и технологических операций, каждая из которых требует специальных материалов и оборудования. Известные полимерные материалы могут быть модифицированы с учётом требований технологии и свойств твердой поверхности, которая играет определяющую роль во взаимодействии с лакокрасочными материалами, приводящими к образованию прочного адгезионного контакта и обеспечивающими требуемые физико-механические и защитно-декоративные свойства покрытия. Сложность физико-химических явлений на границе полимер – твердая поверхность требует использования имеющихся в смежных областях рекомендаций и теоретических представлений. Проведённые исследования позволяют утверждать, что для каждого конкретного сочетания лакокрасочного материала с подложкой устанавливаются параметры, присущие только данной конкретной системе взаимодействия, хотя общий экстремальный характер сохраняется. Проведенные исследования показывают, что подогрев поверхности подложки способствует улучшению смачивания её лакокрасочными материалами, что, в конечном итоге, повышает качество покрытий. Таким образом, если ставится задача рационального выбора технологического процесса отделки, необходимо учитывать влияние многочисленных факторов взаимного влияния межфазовых взаимодействий газовой среды, жидкости и твердого тела. Paint coatings are used various branches of the national economy. Successfully combining a complex of the positive properties inherent in polymeric materials, with decorative and physic-mechanical properties of wood and wood materials, coverings allow to realize successfully numerous tasks of formation of a protective decorative coating at the present stage of scientific and technical progress. Due to the wide use of paint coatings in technique new coating compositions, methods of drawing and methods of formation of coverings are intensively developed, the equipment and research techniques is improved, the range of application extends. In this article which principles results of numerous works in the field of the physical and chemical processes which are taking place liquid on a demarcation – a substrate are at formation of paint coatings the attempt to generalize the saved-up materials for years of researches is made, at the same time aspired to objective assessment, the available data that allows to indicate the need of further development of the scientific representations which are the cornerstone of processes of formation of coverings. Authors sought to open a physical and chemical substance of processes of formation of coverings and to show a process ambiguity of formation of a paint coating. At the same time the attention to concreteness of this or that mode was to a lesser extent paid, and kinetic regularities and tendencies of process are considered. Formation of paint coatings includes the composite complex of stages and technological operations, each of which demands express materials and an inventory. The known polymeric materials can be modified taking into account requirements of technology and properties of a solid surface which plays a defining role in interaction with the coating compositions leading to formation of strong adhesion contact and providing demanded physic-mechanical and protective and decorative with properties of a covering. Complexity of the physical and chemical phenomena on border polymer – the solid surface demands use of the recommendations which are available in interfacing areas and theoretical representations. The conducted researches allow to claim that for everyone concrete a combination of a coating composition to a substrate the parameters inherent only in this concrete system of interaction are set though the common extreme character remains. The conducted researches show that heating of a surface of a substrate promotes wetting improvement by its coating compositions that, finally, increases quality of coverings. Thus, if the task of the rational choice of technological process of finishing is set, it is necessary to consider influence of numerous factors of interference of the phase interactions of a gaseous fluid, liquid and a solid body.


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