Sirvi Autor "Ilves, Risto" järgi
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Kirje Fuel Supply System of Piston Engine Working on Liquid Biofuels(Eesti Maaülikool, 2014) Ilves, Risto; Olt, Jüri (advisor)Most commonly, standard biofuels, e.g. bioethanol E85, biodiesel, biogas, are used. The use of nonstandard biofuels in engines is not widely spread since their physicochemical properties bring about several issues in the engine as well as in the fuel supply system; nevertheless, their manufacturing is less costly (Küüt, 2013). Some of the issues include the increase in the concentration of harmful components in the exhaust gas, the wearing of the fuel supply system, corrosion, excessive soot in the engine, the coking of the injectors, the injectability, ignition, etc (Courtoy et al., 2009; Ma et al., 2004). To reduce the impact of biofuels on the engine and the fuel supply system, fuel blends are taken into use as the mixing of a biofuel with a standard fuel enables to reduce the impact of biofuels. With regard to the wearing of the fuel supply system, dual-fuel supply systems have been developed as these enable the joint use of biofuels and standard fuels. For the use of nonstandard biofuels, it is rational to use either dual-fuel supply systems or additional fuel supply systems. Engines equipped with an additional fuel supply system run on two fuels whereas the standard fuel is injected into the engine by one fuel supply system and the biofuel by the other fuel supply system (examples in literature include Masahiro, 2003; Cipo & Bhana., 2009). A relevant feature in case of the given solution lies in the fact that the air-fuel mixture is formed of two fuels. It is rational to use dual-fuel supply systems in case of spark ignition engines and additional fuel supply systems in case of compression ignition engines. The use of biofuels presents a challenge regarding the concentration of components in the exhaust gas of the engine. For example, when using diesel fuel and bioethanol in a compression ignition engine, the combustion temperature reduces and the ignition delay increases which condition the drop in the combustion pressure and the increase in the concentration of HC in the exhaust gas. To improve the combustion process, one of the possibilities would be to reduce the size of fuel droplets in the air-fuel mixture formed of bioethanol to accelerate the evaporation of bioethanol. This would enable to decrease the combustion time of the airfuel mixture conditioned by the ignition delay. This particular solution enables the use of bioethanol in a compression ignition engine without altering the settings of the engine, e.g. injection timing (Abu-Qudais et al., 2000; Kowalewicz & Pajączek, 2003; Paper I). The aim of the doctoral thesis was to develop a fuel supply system that would enable the dosing of different biofuels into the cylinders of spark and compression ignition engines while ensuring the formation of small fuel droplets in the air-fuel mixture as well as the resistance of the fuel supply system to the physicochemical properties of biofuels. Based on the aim, the first task was to analyse the suitability of existing fuel supply systems for using biofuels in spark and compression ignition engines. The development of the fuel supply system first required an overview of the combustion process of a compression ignition engine as well as of the impact of biofuels on the exhaust gas emission. The abovementioned overview was comprised based on bioethanol fuel. Tests were carried out with the developed fuel supply system during which the formation of the air-fuel mixture and the size of fuel droplets in the air-fuel mixture were studied. The fuel supply system was developed for use in spark and compression ignition engines. Respective tests were carried out. Engine tests were run using 96.4% bioethanol. Based on test results, the impact of the fuel supply system and bioethanol on the combustion process was analyzed. The overall results of the doctoral thesis are as follows: 1. The existing fuel supply systems are designed for the dosing of one type of fuel into an engine. The fuel supply systems of gasoline are suitable for dosing bioethanol and biomethanol, however, their use brings about the wearing of work surfaces and the creation of corrosion. Fuel supply systems designed for the use of diesel fuel are suitable for dosing vegetable oils into the engine (Fendt, Valtra). The main issues in case of vegetable oils include their ignition, combustion, flowability, etc. The formation of the air-fuel mixture is relevant as the physicochemical properties of biofuels differ from those of standard fuels, thus, the quality formation of the air-fuel mixture ensures an effective evaporation and combustion of the air-fuel mixture in the cylinder. 2. When bioethanol is used in a compression ignition engine as an additional fuel, the exhaust gas emission of engines equipped with common rail increases (HC, CO, CO2). In case of engines equipped with a mechanical fuel supply apparatus, the exhaust gas emission mostly decreases (except for HC). To reduce the exhaust gas emission, it is relevant to ensure the high quality air-fuel mixture in the cylinder and the stability of the combustion process. The combustion pressure p of the combustion process can be increased by reducing the size of fuel droplets in the air-fuel mixture. To calculate the combus103 tion pressure p, a model was drawn which enables to calculate the combustion pressure according to the size of droplets in the air-fuel mixture. It is relevant that in case of big fuel droplets (D32 = 100 μm and larger), the increase in the combustion pressure in the cylinder is slow. To be more precise, in case the size range of fuel droplets is D32 = 500…100 μm, the combustion pressure p doubles, respectively to the reduction in the size of fuel droplets. With regard to the droplet size range of D32 = 100…20 μm, the increase in the combustion pressure p is substantially quicker as compared with big fuel droplets. The combustion pressure p increases in case of fuel droplet size range of D32 = 100…20 μm by approximately a twice and half times. In case of fuel droplet size range of D32 = 20…5 μm, the combustion pressure p roughly doubles. Based on the abovementioned, it can be deduced that as the diameter of a fuel droplet is reduced, the combustion pressure p in the cylinder increases. To ensure the stabile operating of the engine and controlled combustion in the cylinder, the recommended size of fuel droplets in the air-fuel mixture is D32 = 15…100 μm. If the fuel droplets are too small, a detonative combustion may occur, which might damage the engine. The abovementioned calculation model also includes several other parameters that depend on the construction of the engine, environmental conditions, etc. Therefore, the combustion pressure calculated by the model may vary in different conditions from 7 – 60%. 3. During the course of the doctoral thesis, two novel fuel supply system solutions were developed (patents EE05665B1 and EE05693B1). Patent EE05665B1 describes a method of air-fuel mixture formation and a fuel supply system operating based on this particular method. The fuel supply system enables to form high quality air-fuel mixture of different fuels and it can be used as an additional or main fuel supply system. Patent EE05693B1 describes an additional fuel supply system which enables to dose liquid biofuels into an engine. This system can only be used as an additional fuel supply system. During the course of work, the solution presented in the patent document EE05665B1 was chosen and it was developed with regard to achieving the aims of the thesis. As a result, a novel fuel supply system was developed, which is more precisely described in the patent application document P201200024 (Patent III) still in process. 4. In case of the air-fuel mixture formed with the developed fuel supply system, the size of fuel droplets in the air-fuel mixture was studied. The results indicated that the size of fuel droplets is mostly affected by the working parameters of the fuel supply system (injection pres104 sure, the distance between injectors) and the viscosity of fuel. As the injection pressure increased, the size of fuel droplets generally reduced, however, the optimal injection pressure in the particular system was determined to be pa = 2 bar. During tests, it became evident that while using diesel fuel, the size of fuel droplets in the air-fuel mixture formed by the developed fuel supply system was smaller than in the air-fuel mixture formed by the mechanical diesel fuel supply apparatus. In case of the developed fuel supply system, the average size of fuel droplets during bioethanol injection was D32 = 22.5 μm. In comparison to the common fuel supply systems developed for dosing gasoline (in-direct injection systems), the size of fuel droplets formed by the pulveriser fuel supply system is approximately four times smaller (the size of bioethanol fuel droplets in a regular PFI injector is D32 ≈ 80 μm). 5. Using the novel fuel supply system as an additional fuel supply system of a compression ignition engine and dosing 96.4% bioethanol into the engine as an additional fuel, the following conclusions were arrived at: 5.1. The construction and control devices of the fuel supply system are suitable for use on a compression ignition engine. 5.2. During tests, it became evident that using bioethanol as a diesel engine fuel is rational at elevated rotational speeds on engine idle mode (the nominal rotational speed of the engine) or on engine load. The heat release from the process is too small on engine idle mode to ensure the quality combustion of bioethanol fuel. 5.3. The stability of the combustion process, the increase in the heat release rate and the intensified heat release are ensured when an airfuel mixture of small fuel droplet size (bioethanol proportion of up to 25%) is used at elevated rotational speeds on idle mode in a compression ignition engine. When the proportion of bioethanol in the airfuel mixture is increased over 25%, the intensity of heat release and the combustion pressure decrease whereas the proportion of gross heat release in the combustion process increases. 5.4. At elevated rotational speeds of the crankshaft in a compression ignition engine (an engine equipped with a mechanical fuel supply apparatus), generally, the proportion of HC in the exhaust gas increases. The proportion of HC increased in case of air-fuel mixtures with different bioethanol fuel proportions. This may have been caused by the creation of water vapour during bioethanol combustion which hinders the complete combustion of diesel fuel. This particular issue requires complementary study in further research. 6. When using the novel fuel supply system in a spark ignition engine, the following conclusions were arrived at: 6.1. When using the pulveriser fuel supply system, fuel consumption decreased in comparison to the original fuel supply system of the test engine as follows: by ~6% in case of gasoline and by ~3% in case of bioethanol. During tests, it became evident that as engine load increased, the bioethanol consumption of the engine increased rapidly in the pulveriser fuel supply system. This was conditioned by firstly, the construction of the fuel supply system, which did not enable the sufficient air flow into the engine, and secondly, ignition timing, which conditioned the quicker combustion of the air-fuel mixture. As a result, the maximum value of combustion pressure was achieved at top dead centre of the engine or a few crank angle degrees after it, which may have caused the countermining of the combustion pressure to the upward movement of the piston. 6.2. When using an air-fuel mixture of small fuel droplet size, the combustion pressure and heat release rate increased in the engine. In further research, it is necessary to adjust the ignition angle so it would be suitable for the engine since this would ensure the maximum of combustion pressure after the top dead centre of the piston. During the use of the pulveriser fuel supply system, the combustion pressure and heat release rate increased. In further research, it is necessary adjust the ignition angle to be suitable for the engine so that the maximum of combustion pressure after the top dead centre of the piston would be ensured. 7. During tests with the developed fuel supply system, it became evident that its use enabled to reduce fuel consumption in the engine and ensure the effective combustion of the air-fuel mixture in the engine. An increase in the combustion pressure is conditioned by several influencing factors, e.g. the size of fuel droplets, however, combustion pressure might be affected by the length of the intake manifold, the homogeneity of the air-fuel mixture and the construction of the fuel supply system. The particular thesis outlines the positive effect of the fuel supply system on the combustion process of the engine; nevertheless, it is necessary to further research which of the abovementioned influencing factors impacts the efficiency of the particular system more specifically. 8. In case of the given solution, it is first necessary to solve several constructional issues of the system before arriving at final conclusions about the effectiveness of the fuel supply system. However, these issues can be solved during the further design process of the product.Kirje Research into the parameters of a potato harvester's potato heap distributor, and the justification of those parameters(Estonian Academic Agricultural Society, 2021) Olt, Jüri; Adamchuk, Valerii; Korniushyn, Viktor; Melnik, Viktor; Kaletnik, Hryhoriy; Ihnatiev, Yevhen; Ilves, Risto; Estonian University of Life Sciences. Institute of TechnologyThe low levels of efficiency and general quality when it comes to the use of potato harvesters in difficult soil and climatic conditions substantiate the relevance of the problem which is faced in terms of research by technologically advanced equipment and tools. They are looking to increase the efficiency of potato harvesters. This paper serves to justify the formation of the design and technical parameters of the V-type distributor, which directly acts on the undermined mass to increase the ability of the potato harvester to separate the soil. Preliminary experimental studies have shown that to achieve efficient technological processing in terms of the distribution of the general soil and potato heap, the distributor must possess the appropriate technological and design parameters. Calculations which have been carried out by using as a basis the theoretical dependencies that have been obtained serve to allow us to determine the optimum speed of progress through the heap, using the following design and kinematic parameters: Vel = 2.0 m s–1, А = 0.35 m, hv = 0.22 m, Δ = 0.08 m, bel = 1.2 m. The allowable speed for heap movement will be [V] = 1.62 m s–1, which will ensure the prevention of any heap clogging in front of the distributor. An analysis of the dependencies which have been obtained during the work shows that rational values for the distributor wing’s fitting angle fall within the range of α = 40°.Kirje Study on performance of compression engine operated by biodiesel fuel(Estonian University of Life Sciences, 2020) Kaletnik, H.; Mazur, V.; Gunko, I.; Ryaboshapka, V.; Bulgakov, V.; Raide, Veljo; Ilves, Risto; Olt, JüriThe performance analysis of the biofuel energy efficiency in the combustion engine is as function of the fuel’s composition and other physical-chemical parameters. Different models and analysis do not take into account the effect that the use of different bio-diesel fuels has on the operation of the engine. Refinement is needed in describing the physical processes taking place in the engine’s cylinders. The aim of the study is the development of a mathematical model for the practical analysis of the efficiency of use of biofuel on diesel engines, which would take into account the fuel’s composition. The developed model in the article is designed to develop the 4Ч11.0/12.5 diesel engine.Kirje Study on performance of compression engine operated by biodiesel fuel(2020) Kaletnik, H.; Mazur, V.; Gunko, I.; Ryaboshapka, V.; Bulgakov, V.; Raide, Veljo; Ilves, Risto; Olt, Jüri; Estonian University of Life Sciences. Institute of TechnologyThe analysis of the performance of biofuel is aimed at evaluating the energy efficiency of operating the engine with the use of biodiesel fuel as function of the fuel’s composition and other physical-and-chemical parameters. The mathematical models and analysis techniques known to the authors do not take into account the effect that the use of different bio-diesel fuels has on the operation of the engine and, therefore, need refinement in terms of the mathematical expressions and empirical formulae that describe the physical processes taking place in the engine’s cylinders. The aim of the study is to improve the mathematical relations taking into consideration the physical-and-chemical parameters of different types of fuel. The research methods proposed in the article are based on step-by-step consideration of the mathematical models of processes that follow each other, with due account for their possible overlapping, which jointly have an effect on the engine’s output indices. The boundary conditions and parameter increments are pre-set in electronic work sheets. Thus, it becomes possible, using the refined mathematical model, to calculate the main performance indices of the diesel engine with due account for the changes in the physical-and-chemical parameters of the fuel. The novelty of the described approach is in the possibility, through the use of the refined model and taking into account the data on the composition of the fuel and the design and operation parameters of the engine, to calculate the indices that allow evaluating the efficiency of use of specific fuels in the internal combustion engine under consideration. In results, formulas for the calculation of the effective power of the engine, fresh air charge density, excess air factor, effective specific fuel consumption and combustion pressure have been developed. Combustion pressure modelling and experimental data is presented.Kirje Ülevaade: Põllumajandusliku masinapargi arengud Eestis ajavahemikul 2010–2018(Estonian Academic Agricultural Society, 2019) Olt, Jüri; Ilves, Risto; Küüt, Arne; Eesti Maaülikool. Tehnikainstituut. Biotehnoloogiate õppetoolThe aim of the current research is to provide an overview of the trends in the park of agricultural machinery in Estonia during the period 2010–2018. For this purpose, data obtained from the registers of Agriculture and Transport of Statistics Estonia have been used. The article outlines, firstly, changes in the number of agricultural holdings by the size of arable land and growing area of grain, secondly, changes in the number of tractors and grain harvesters, including the number of new tractors and harvesters sold over the years, thirdly, the preferences of holdings for tractors and grain harvesters, and fourthly, the categorization of new tractors and grain harvesters by the manufacturing company in the given time period. What is more, developments concomitant with trends in the park of agricultural machinery have been described.