Prediction of gaseous pollutant emissions from a spark-ignition direct-injection engine with gas-exchange simulation

With the further tightening of emission regulations and the introduction of real driving emission tests (RDE), the simulative prediction of emissions is becoming increasingly important for the development of future low-emission internal combustion engines. In this context, gas-exchange simulation can be used as a powerful tool for the evaluation of new design concepts. However, the simplified description of the combustion chamber can make the prediction of complex in-cylinder phenomena like emission formation quite challenging. The present work focuses on the prediction of gaseous pollutants from a spark-ignition (SI) direct injection (DI) engine with 1D–0D gas-exchange simulations. The accuracy of the simulative prediction regarding gaseous pollutant emissions is assessed based on the comparison with measurement data obtained with a research single cylinder engine (SCE). Multiple variations of engine operating parameters – for example, load, speed, air-to-fuel ratio, valve timing – are taken into account to verify the predictivity of the simulation toward changing engine operating conditions. Regarding the unburned hydrocarbon (HC) emissions, phenomenological models are used to estimate the contribution of the piston top-land crevice as well as flame wall-quenching and oil-film fuel adsorption-desorption mechanisms. Regarding CO and NO emissions, multiple approaches to describe the burned zone kinetics in combination with a two-zone 0D combustion chamber model are evaluated. In particular, calculations with reduced reaction kinetics are compared with simplified kinetic descriptions. At engine warm operation, the HC models show an accuracy mainly within 20%. The predictions for the NO emissions follow the trend of the measurements with changing engine operating parameters and all modeled results are mainly within ±20%. Regarding CO emissions, the simplified kinetic models are not capable to predict CO at stoichiometric conditions with errors below 30%. With the usage of a reduced kinetic mechanism, a better prediction capability of CO at stoichiometric air-to-fuel ratio could be achieved.</p

Об окраске синтетического флюорита и о вкрапленном в него графите

Окраска флюоритов давно привлекает к себе внимание исследователей. Автор исследовал синтетический флюорит, который, исходя из весьма высокой чистоты материалов, ожидался оптически бесцветным. На деле полученный флюорит неравномерно окрашен в зеленый и синий цвета различной интенсивности. Исследование этого кристалла в тонких пластинках, параллельных {III}, показало, что флюорит в различной степени переполнен дисперсно-рассеянным графитом. Графит присутствует в форме гексагональных кристалликов. Его пластинчатые кристаллики откладываются на поверхностях граней октаэдра. В проходящем свете тонкие пластинки графита просвечивают или почти прозрачны, ясно плеохроируют от светло-зеленого до бледно-синеватого. В отраженном свете блеск металловидный. Показатель преломления около 2. Что касается самого флюорита, то его пластинки, параллельные {III}, после травления соляной кислотой показали, что они сплошь усеяны ориентированными вершинами очень мелких кубиков. Общая картина травления поверхности напоминает сложение кристаллов полиэдрами, по Гаюи. Причина окраски изучаемых флюоритов ясна: она 'определяется дисперсно-рассеянным графитом

Development of Phenomenological Models for Engine-Out Hydrocarbon Emissions from an SI di Engine within a 0D Two-Zone Combustion Chamber Description

The increasingly stringent limits on pollutant emissions from internal combustion engine-powered vehicles require the optimization of advanced combustion systems by means of virtual development and simulation tools. Among the gaseous emissions from spark-ignition engines, the unburned hydrocarbon (HC) emissions are the most challenging species to simulate because of the complexity of the multiple physical and chemical mechanisms that contribute to their emission. These mechanisms are mainly three-dimensional (3D) resulting from multi-phase physics - e.g., fuel injection, oil-film layer, etc. - and are difficult to predict even in complex 3D computational fluid-dynamic (CFD) simulations. Phenomenological models describing the relationships between the physical-chemical phenomena are of great interest for the modeling and simplification of such complex mechanisms. In addition, phenomenological models can be applied within simplified simulation environments, e.g., 0D-1D engine simulations, to enable predictions of HC emissions for a wide range of operating conditions. In this work, the development of phenomenological models to account for HC emissions from piston top-land crevices, wall flame quenching, and oil-film adsorption/desorption mechanisms is explained in detail. The model development is based on measurements and models from a single cylinder direct injection (DI) spark ignition (SI) research engine. Common modeling hypotheses and approaches from literature have been verified and further developed with 3D-CFD simulations. In particular, assumptions regarding local temperature and air-fuel ratio, which are necessary for HC modeling, have been developed on the basis of a zone post-processing of the 3D-CFD results. Additionally, a novel approach to describe HC post-oxidation, which is based on 0D-chemistry calculations, has been developed. The HC models have been implemented within a GT-POWER model of the engine in conjunction with a 0D two-zone combustion chamber description. The accuracy of the developed models has been tested against a large experimental database with varying engine load, speed, air to fuel ratio, valve timing, and oil/coolant temperature. The deviation in the HC emission prediction is mainly within 20% at warm engine operation. Higher deviations are observed at cold engine conditions because of the absence of secondary HC models which have not been considered in the present work.</p

The investigation of the production environment factors through the prism of the game process

У сучасному світі широко використовується гейміфікація, як один з найбільш ефективних підходів в навчанні. Гейміфікація застосовується з метою залучення користувачів, підвищення їхньої зацікавленості у вирішенні прикладних завдань. Однією з найбільш ефективних методик виступає ділова гра. У процесі її моделювання визначається проблемна ситуація, і мета гри полягає в пошуку шляхів її вирішення. Ділові ігри застосовуються як в освітній, так і діловій сферах. Важливе значення ділових ігор полягає також в тому, що вони сприяють встановленню відносин співробітництва викладача і студентів, обумовлюють формування позитивного емоційно-психологічного клімату на заняттях. Розроблена і впроваджена в навчальний процес робота "Office Explorer" - це візуальний інструмент у вивченні впливу факторів виробничого середовища і трудового процесу на стан здоров'я людини і навколишнього середовища. Створена така універсальна програма, яка в ігровій формі доступно, не нав'язливо донесе інформацію до студента, заставить проаналізувати, засвоїти, зробити правильні висновки, обрати необхідні засоби і заходи захисту від впливу шкідливих чинників виробничого середовища і трудового процесу. Програма "Office Explorer" об'єднала в собі всі ці вимоги до комп'ютерних лабораторних робіт і стала незамінним інструментом в засвоєнні знань і практичних навичок з дисциплін "Безпека життєдіяльності" та "Основ охорони праці". Реалізований підхід є найсучаснішим рішенням висвітленої проблеми сучасних заходів навчання та оцінювання знань студентів ВНЗ. Використання цього підходу дозволяє автоматизувати навчальний процес, а також готує майбутнього спеціаліста до умов вирішення реальних проблем. Використання подібних робіт при різних формах навчання дуже важливо і необхідно в сучасних умовах.In the modern world, gaming is widely used as one of the most effective approaches in the teaching. Gaming is used to attract users, increase their interest in solving applied problems. One of the most effective techniques is the business game. In the process of its simulation, the problem situation is determined, and the purpose of the game is to find ways to solve it. Business games are applied both in educational and business spheres. The importance of business games is also that they contribute to the establishment of relations between the teacher and students, which determine the formation of a positive emotional and psychological climate in the classes. The "Office Explorer" work developed and implemented in the educational process is a visual tool in studying the influence of the working environment factors and the working process on the condition of human health and the environment. The Office Explorer program combines all these requirements with computer labs and has become an indispensable tool in acquiring knowledge and practical skills in the disciplines "Security of Life" and "Fundamentals of Occupational Safety". The implemented approach is the most up-to-date solution of the illuminated problem of modern educational measures and assessment of students' knowledge of universities. Using this approach allows you to automate the learning process, as well as prepare a future specialist for the conditions for solving real problems. The using of such works in various forms of training is very important and necessary in the modern conditions

Presencia, distribución y evolución de paligorskita en suelos sobre sedimentos terciarios de la Cuenca del Duero.

8 p.[ENG]Palygorskite distribution and evolution in the clay fraction of nine soil profiles developed from Tertiary sediments of the Duero Basin, have been studied. The mineral encountered in clay fraction, studied adopting XRD, DTA and TEM techniques, are illite as predominant component, low quantities of kaolinite, me dium or low amounts of smectite and palygorskite. Palygorskite contents were observed to be higher in the subsoil than the top soil and, in Ap horizonts, it lacks or is observed only in very small quantities. The amount of smectite increases when palygorskite content decreases, but in some of the Ap horizonts, the amount of smectite also decreases by destruction process and or washing of it to accumulation horizonts.[ESP]Se estudia la distribución y evolución de paligorskita en la fracción arciIla de nueve perfiles de suelos desarrollados sobre sedimentos y rocas sedimentarias en el terciario de la cuenca del Duero. La fracción arcilla estudiada empleando las técnicas de difracción de rayos X, ATD y MET, esta compuesta de ilita como mineral dominante, acompañada de pequeñas proporciones de caolinita y medias o bajas de esmectita. La paligorskita. más abundante en los horizontes subsuperficiales, disminuye al ascender en los perfiles, disminuci6n que suele ir acompañada por un aumento en la proporción de esmectita. En los horizontes antrópicos desaparece o sufre una fuerte disminución el contenido en paligorskita y en algunos disminuye notablemente el contenido en esmectita debido a un proceso de destrucción y/o lavado de la misma hacia horizontes de acumulación

Development of Phenomenological Models for Engine-Out Hydrocarbon Emissions from an SI di Engine within a 0D Two-Zone Combustion Chamber Description

The increasingly stringent limits on pollutant emissions from internal combustion engine-powered vehicles require the optimization of advanced combustion systems by means of virtual development and simulation tools. Among the gaseous emissions from spark-ignition engines, the unburned hydrocarbon (HC) emissions are the most challenging species to simulate because of the complexity of the multiple physical and chemical mechanisms that contribute to their emission. These mechanisms are mainly three-dimensional (3D) resulting from multi-phase physics - e.g., fuel injection, oil-film layer, etc. - and are difficult to predict even in complex 3D computational fluid-dynamic (CFD) simulations. Phenomenological models describing the relationships between the physical-chemical phenomena are of great interest for the modeling and simplification of such complex mechanisms. In addition, phenomenological models can be applied within simplified simulation environments, e.g., 0D-1D engine simulations, to enable predictions of HC emissions for a wide range of operating conditions. In this work, the development of phenomenological models to account for HC emissions from piston top-land crevices, wall flame quenching, and oil-film adsorption/desorption mechanisms is explained in detail. The model development is based on measurements and models from a single cylinder direct injection (DI) spark ignition (SI) research engine. Common modeling hypotheses and approaches from literature have been verified and further developed with 3D-CFD simulations. In particular, assumptions regarding local temperature and air-fuel ratio, which are necessary for HC modeling, have been developed on the basis of a zone post-processing of the 3D-CFD results. Additionally, a novel approach to describe HC post-oxidation, which is based on 0D-chemistry calculations, has been developed. The HC models have been implemented within a GT-POWER model of the engine in conjunction with a 0D two-zone combustion chamber description. The accuracy of the developed models has been tested against a large experimental database with varying engine load, speed, air to fuel ratio, valve timing, and oil/coolant temperature. The deviation in the HC emission prediction is mainly within 20% at warm engine operation. Higher deviations are observed at cold engine conditions because of the absence of secondary HC models which have not been considered in the present work.</p