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Mitigating vibration of internal combustion engines
Kožuch, Jonáš ; Böhm, Michael (referee) ; Fridrichová, Kateřina (advisor)
This bachelor thesis deals with the problem of vibration damping of internal combustion engines. It gives an overview of the causes of vibration and describes them. The most dangerous phenomenon for the crankshaft is torsional vibration, and it is therefore important to eliminate this phenomenon as much as possible. An overview of current torsional vibration damping solutions is given. Torsional vibration dampers are divided into different groups. The division is mainly based on the type of construction and the way in which the dampers eliminate the vibrations. The final part focuses on the simulation of the crank dynamics in GT-Suite. In the simulations, the parameters of the rubber torsional damper are varied, specifically the moment of inertia and the Maxwell model settings. Then, their effect on torsional vibration is investigated. The output is the ideal damper parameters for a given engine model.
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Increasing the efficiency of the diesel engine emission system
Stráník, Daniel ; Fridrichová, Kateřina (referee) ; Böhm, Michael (advisor)
This thesis addresses the issue of emission from heavy-duty vehicles with diesel engine. Perfect combustion in the engine is unattainable, leading to the inevitable production of pollutants during diesel combustion that must be effectively eliminated. Emission systems are used to reduce pollutants present in exhaust gases. As emission limits continue to decrease, and with the impending introduction of the new Euro VII emission standard, it is still important to reduce emission from internal combustion engines. This is particularly significant as electric and other alternative drives are not yet sufficiently developed for heavy-duty vehicles. This thesis proposes a strategy for achieving the greater reduction of pollutants and the desired increase in the efficiency of the entire emission system. For this purpose, a numerical model was created using GT-Suite software, and simulations were conducted to replicate the WHSC and WLTC class 1 driving cycles for the simulation of steady and transient states. The emissions resulting from the modified emission system were compared with those from the default system. The conclusion of the thesis is a brief description and evaluation of the results, accompanied by an outline of potential future procedures.
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Exhaust Temperature Stabilitation Systems for Turbocharged Engines
Böhm, Michael ; Charvát, Pavel (referee) ; Vondrák, Adam (referee) ; Štětina, Josef (advisor)
This paper describes the possibilities of reducing temperature pulsations in the exhaust manifold of an internal combustion engine. For this purpose, the concept of a heat reservoir with a phase change material that can store the heat generated in the exhaust manifold is chosen. At a temperature lower than the phase change temperature of this material, the heat storage is then able to transfer the heat back to the exhaust gas, thereby reducing the temperature pulsations. The actual design consists of an advanced heat storage design consisting of an assembly of smaller tubes that increase the heat output of the storage while causing minimal pressure drop in the exhaust manifold. This concept is validated and compared with a series engine without a stack through simulations in both 1D and 3D computing environments. The designed and constructed prototype stack is subjected to experimental testing to confirm its performance. The effects of the electrically assisted turbocharger on the exhaust gas temperature are also analyzed. Finally, all the results are summarized showing the overall potential of this system and a possible way forward in the development of these stacks with phase change materials is outlined.
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Synthetic and alternative fuels for internal combustion engines
Kromp, Miloš ; Zeizinger, Lukáš (referee) ; Böhm, Michael (advisor)
The bachelor’s thesis focuses on synthetic and alternative fuels for combustion engines. Types of fuels, production and distribution processes, and their impact on combustion and engine performance are examined. The work also analyzes the impacts of these fuels on CO2 emissions. An innovative part is the usage of a simulation model of the engine, which allows comparison of performance parameters and emissions when using different types of fuels. This method brings new possibilities for optimizing the use of alternative fuels.
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Conversion of a gasoline engine to burn hydrogen
Prchal, David ; Böhm, Michael (referee) ; Drápal, Lubomír (advisor)
The master’s thesis deals with the hydrogen combustion in reciprocating internal combustion engines, a topic that is becoming more important with the planned transition to low-emission mobility. basic physical properties of hydrogen, which are compared with conventional hydrocarbon fuels. Differences in terms of mixture formation, heat release rate, heat transfer, performance, emissions and other operating parameters are described. Based on the information found, a theoretical proposal for the conversion of the 1.5 TSI evo2 gasoline engine to hydrogen combustion is made, with emphasis on achieving sufficient power, a suitable torque curve, low emissions and the lowest possible conversion costs. Data from other hydrogen spark ignition engines are analysed and few different combustion models for hydrogen are developed. A simplified 1D model of the baseline engine is created and modified for hydrogen applications. A new intake cam profile is designed for the high engine load, the approximate size of the required turbocharger is recommended, intake air cooling requirements are determined and minor structural modifications to the cylinder head are proposed. The result meets the stated objectives and demonstrates that modern spark ignition internal combustion engines can be used in combination with hydrogen as a low-emission fuel with low conversion costs.
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Hydrogen and safety in transport
Rusek, Rostislav ; Böhm, Michael (referee) ; Poulíček, Matěj (advisor)
This bachelor thesis identifies the risks associated with the leakage, storage and handling of hydrogen as a promising low-emission fuel of the future. It starts by giving the basic characteristics of hydrogen, or its storage and transport methods. It then analyses existing safety measures, describes hydrogen transport and technological innovations from an economic and environmental perspective. The final section compares hydrogen with alternative fuels, namely compressed natural gas and liquefied petroleum gas. This thesis is based on a search of the relevant literature, summarises current knowledge and highlights the need for further research to ensure a secure future for hydrogen as an alternative fuel in transport vehicles and infrastructure.
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Direct combustion of the Hydrogen in the combustion engine
Veger, Lukáš ; Poulíček, Matěj (referee) ; Böhm, Michael (advisor)
This bachelor's thesis deals with the comparison of hydrogen as a fuel for an internal combustion engine against conventional fuels used in vehicles. The quantities compared are density, energy required for ignition, stoichiometric ratio, calorific value, octane number and flame propagation speed. The second part is devoted to the analysis of the implementation of hydrogen as a fuel for an internal combustion engine, both compression ignition and spark ignition. Important elements of prevention against hydrogen leakage or prevention of its concentration outside the combustion space were also described here. A well-to-wheels comparison of hydrogen production using the SMR method, and the solar electrolysis method was conducted, where the energy consumption and the production of harmful emissions were compared. Furthermore, the parameters of individual drive systems were compared, which included a conventional petrol engine, an electric drive, a hybrid drive, a biofuel burning engine, a hydrogen combustion engine, and a hydrogen fuel cell. The monitored parameters were the production of carbon dioxide and sulfur dioxide emissions, energy efficiency and range. Finally, the simulation compared a hydrogen spark ignition engine with a gasoline spark ignition engine. Gt-suite program was used. The monitored parameters were performance parameters, production of nitrogen oxide emissions, specific fuel consumption and the dependence of the course of pressure in the combustion chamber on the rotation of the crankshaft.
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Thermodynamic 1-D model of the turbocharger of an internal combustion engine
Mrázková, Kristýna ; Böhm, Michael (referee) ; Štětina, Josef (advisor)
Master thesis deals with 1D heat transfer simulation of turbine housing laying emphasis on temperature of exhaust gas leaving the turbine. The thesis covers construction and thermodynamics of turbochargers, exhaust gas aftertreatment and heat transfer simulation software. Then the thesis focuses on exploring turbine housing 3D model discretization, building physical turbocharger model for 1D simulation of exhaust gas output temperature and heat transfer through turbine housing. Heat transfer coefficients were calibrated for transient simulation predicting temperature of output exhaust gas in compliance with NEDC cycle. Results analysis and optimization follow, a suggestion on model integration into the virtual turbocharger system is also included.
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Charge Efficiency of a Gasoline Turbocharged Engine
Holas, Tomáš ; Böhm, Michael (referee) ; Svída, David (advisor)
This bachelor thesis deals with the topic of volumetric efficiency of a gasoline turbocharged engine. The first part of this thesis is devoted to research on this topic. In the second part of the thesis an analysis of data from a 1.5 TSI engine from the Volkswagen group line-up obtained during the WLTP test was performed. This analysis was achieved by the means of creating regression models on the measured data and comparing their results. The result of this analysis was the determination of the main ordinarily measured parameters on which the volumetric efficiency depends.
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Predicting spark-ignition engine emissions
Jirout, Petr ; Böhm, Michael (referee) ; Štětina, Josef (advisor)
This diploma thesis deals with the possibility of predicting emissions of SI engines. The aim was to create an algorithm for predicting unburned hydrocarbons and carbon monoxide, based on ECU signals. The algorithm is based on practical experiments with SI engines. In the summary, the issues and the possible use of the created algorithm following the incorporation of EU7 are outlined.
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