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[en] Highlights: • The gross IMEP is approximately proportional to engine cylinder pressure at BDC. • The mechanism and influence factors of intake loss in CVVL and VVT engines were compared. • The theoretic limitations of engine intake loss were deduced. • The suggestions were proposed for CVVL engine to approach the theoretical minimum pumping loss. • The BSFC of CVVL engine can be further reduced by more than 20%. VVL and VVT are two common approaches to reduce engine pumping loss at part loads, however, the comparative study on their potentials and influence factors of pumping loss reduction is scarce. In this paper, the gas exchange processes of CVVL and VVT engines were investigated by bench testing. The mechanism and influence factors of pumping loss in the two types of engines were comparatively analyzed, the theoretic limitations of pumping loss in intake process were deduced and the suggestions to approach the theoretic minimum were proposed. The results show that the gross indicated mean effective pressure (IMEP) of engine is approximately proportional to cylinder pressure at bottom dead center (BDC) for both traditional throttle control strategy and early intake valve closing (EIVC) strategy. The difference of pumping losses between CVVL and VVT engines results from intake process. Due to the differences of intake modes, the CVVL engine has lower intake loss than VVT engine by nature. The pumping loss in intake process of CVVL engine is much closer to the theoretical minimum, and the BSFC of CVVL engine can be reduced by more than 20% at 2000 r/min and 2.3 bar IMEP by increasing the maximum lift of intake valve. All these have provided guidance for pumping loss reduction of gasoline engine.
[en] Dimensionless characteristics of turbines are discussed. On that basis, a universal method of mathematical approximation is formulated. The approximation of the turbine characteristics in a TKR-10ST turbocompressor is considered, as an example.
[en] In the article was held a critical discussion on the challenges facing the cooling system of thermal engines in the light of modern requirements. These issues are directly related to new tendencies in the construction of internal combustion engines, including those concerning increasing unit power, application of the Atkinson and Miller theoretical cycles, and cooperation of heat engines with electric machines. (paper)
[en] With the development of internal combustion engine, how to design complicated parts of internal combustion engine quickly and effectively is of great significance. In view of the rapid prototyping design research of internal combustion engine parts, we firstly formulate a prototype model design criterion. From the sketch parameterization, shape feature parameterization and assembly parameterization design ideas, we propose a parameterized model construction method in order to meet the requirements of model accuracy and extensibility in the top-down design of internal combustion engine. Then according to the performance of internal combustion engine and the structure characteristics of main parts, we develop a system design process and a part design process. At the same time, we put forward a top-down design platform for internal combustion engine, analyse platform development functions, platform development framework and platform development process. Finally accomplishing the prototype of internal combustion engine based on NX development and a complete development technology system of internal combustion engine platform so as to improve the success rate of internal combustion engine design. (paper)
[en] Highlights: • The relevant properties of practical optical materials were collected and presented in a readily navigable format. • Mechanical properties of optical materials are found to be inconsistent for elevated temperatures and for fatigue loads. • In response to the unreliable material data increased safety factors are required, detailed recommendations are provided. • As function of application, clear design criteria recommendations are shown. • Aspects of opto-mechanical performance were described in depth and newly developed equations and relations are presented. In this study, the design aspects of optically accessible pressure vessels are investigated via a case study of a High Pressure Combustor experimental rig. The rig was designed to take optical measurements of combustion, simulating the conditions found in internal combustion engines and turbines. Although, it is not new to equip chambers and reactors with sight windows, important aspects of design and relevant information regarding optical access is missing or are insufficiently explored or not readily accessible in the existing literature. A comprehensive review of requirements for optical access to such high-pressure, high-temperature systems has been conducted. It is shown in a readily-navigable format as function of application and precision, with data and technical correlations hitherto not found in a ‘user-friendly’ style. The material selection procedure is detailed and supported by a complete comparison of optical materials and relevant properties. The review revealed a significant inconsistency in mechanical properties claimed in the literature for optical materials. As a response to this, increased safety factor values are suggested as function of level of uncertainties and effects of failure, typically three to four times higher than the industrial standard. Moreover, newly developed equations are presented linking performance analysis to the design criteria.
[en] Main subject of this thesis is to contrast gasoline and ethanol fuel combustions by measuring effective parameters. Introduction to the research part comprises theoretical description of alternative fuels available for gasoline engines. Next, it was describe preparation to research, also research itself and the results analysis. Results contain graphs of parameters: the pressure in the engine cylinder, the rate of pressure changes in the cylinder (as a function of crank angle). Results also contain graphs of parameters torque, engine efficiency, concentration of toxic exhaust components (as a function of the air–fuel equivalence ratio (λ) and as a function of the spark advance angle). There parameters are shown for constant the crankshaft rotational speed, for constant throttle position. Research confirmed that the use of ethanol fuel does not cause significant losses or gains in terms of effective parameters. (paper)
[en] The purpose of this study is to prevent the stick, scuffing, scratch between piston and cylinder in advance, to obtain data for duration test in actual engine operation. The temperature gradient in cylinder bore according to coolant temperature were measured in use of 1.5 liter class gasoline engine 20 thermocouples were installed at points of 2mm inside from cylinder wall near top ring of piston in cylinder block, which points have suffered major thermal loads and suggested as proper measurement points for engine design by industrial engineers. Under full load and 70 .deg. C, 80 .deg. C and 90 .deg. C coolant temperature conditions, temperature of cylinder block, engine oil, exhaust gas in exhaust manifold, fuel consumption and engine performances were measured. The results obtained are summarized as follows : 1) The temperature in cylinder block and engine oil increased gradually in according to the increase of coolant temperature. 2) The siamese side temperature of top dead center is 142 .deg. C in peripheral distribution, it is about 20 .deg. C higher than thrust, anti-thrust, rear side temperature, 3) The fuel consumption in 70 .deg. C coolant temperature is lower than 80 .deg. C, 90 .deg. C coolant temperature. 4) The engine torque in 80 .deg. C, 90 .deg. C coolant temperature condition is about 0.5kg.m higher than 70 .deg. C coolant temperature
[en] One of attractive methods for in-place diagnostics of internal combustion engines is the method based on using the generalized Bayes formula of conditional probabilities. The article is devoted to the applicability improvement of the Bayes algorithm for assessing the technical condition of internal combustion engines. The use of this algorithm involves the compilation of a diagnostic table, the elements of which are conditional probabilities of selected diagnoses in case of a range of faults. Their relevant determination requires a large amount of statistical data, which is often lacking. To supplement deficient data and increase the reliability of obtained results, the authors propose to use a method for simulating patterns of changes in design parameters of the technical condition of internal combustion engines depending on operating time. (paper)
[en] The quality of the fuel mixture in the cylinders of an internal combustion engine is determined by the electronic control unit based on the co-operating information with the electronic throttle unit. For this reason, any malfunction of the components of the electronic throttle unit strongly influences the quality of the fuel mixture and the performance of the internal combustion engines. In this context, in this paper, experimental and theoretical researches were carried out by simulating the failures that can occur at the level of the electronic throttle unit and their influence on the pollutant emissions of the internal combustion engines. (paper)
[en] The paper presents a method for analysing tri-generation systems. The authors have focused on solutions of tri-generation plants based on gas turbine or internal combustion engine with absorption chilling machine. Several technical criteria have been defined. A thermodynamic analysis has been performed for the case of tri-generation with an absorption chilling machine. From the thermodynamic point of view there have been established the limits for the best energetic performance of tri-generation. The dependence of different technical criteria on each other has also been analysed. A certain case of a tri-generation plant has been analysed using this method. The dependence of the energetic performance of tri-generation on different technical criteria has also been studied