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[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] 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] 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] Highlights: • Fuel’s ignition and combustion characteristics are measured by different method. • Diesel blends containing 20% and 40% n-pentanol are examined. • D60P40 advances ignition phase over D80P20 under low oxygen content conditions. • Flame luminosity is reduced with the increase of pentanol ratio in most conditions. • Pentanol could significantly accelerate soot oxidation under all conditions. - Abstract: Pentanol is considered as one of the most promising alternative biofuels due to its excellent physicochemical properties. The objective of this work was to compare the ignition and combustion characteristics of different n-pentanol/diesel blends in an optical constant volume combustion chamber. The tested fuels included 20% (D80P20) and 40% (D60P40) of n-pentanol blended with diesel in volume, and pure diesel (D100). Broadband chemiluminescence technique was used to measure the timing and location of spray ignition. A high-speed CCD camera with two ND8 dimmer lenses was used to capture the incandescence radiated from the soot particles during combustion. A wide range of experimental conditions was investigated. The ambient temperature ranged from 800 K to 1200 K and the oxygen concentration ranging from 10% to 21%, covering both the conventional and low temperature combustion regimes. The results show that pure diesel has shorter ignition delay and distance comparing to pentanol blends. A larger blending proportion of pentanol D60P40 advances the ignition phase more than the D80P20 in low oxygen concentration conditions. Due to the fuel-borne oxygen and the dilution effect, the natural flame luminosity is reduced significantly with the increase of pentanol ratio in most conditions except under the intermediate temperature region of 1000 K. In that condition, the shorter ignition delay and flame lift-off length of pentanol blends cause a slightly increase in the natural flame luminosity. The natural flame luminosity images showed that the oxygen-contained structure of pentanol could accelerate soot oxidation under all conditions. This indicates that pentanol blends could decrease final soot emissions in internal combustion engines.
[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
[en] Using a continuous wavelet transform we have analyzed the cycle-to-cycle variations of pressure in an internal combustion engine. The time series of maximum pressure variations are examined for different loading and their wavelet power spectrum is calculated for each load. From the wavelet power spectrum we detected the presence of long, intermediate and short-term periodicities in the pressure signal. It is found that depending on the load, the long and intermediate-term periodicities may span several cycles, whereas the short-period oscillations tend to appear intermittently. Knowledge of these periodicities may be useful to develop effective control strategies for efficient combustion
[en] Based on the analysis of the first firing cycle (FFC), this paper presents the combustion and emissions characteristics at cold-start and their related parameters, such as excess air coefficient in a small EFI SI engine fuelled with LPG at environmental temperature from -9oC to +4oC. The results show that the FFC ignition reliability, instantaneous engine speed and HC emissions are strongly dependent on the excess air coefficient at cold-start. The environmental temperature has a great influence on HC emissions of the FFC, except for engine's start-up speed. The optimum excess air coefficient to guarantee the successful FFC at cold-start of LPG engine was found. The judgment of key factors to guarantee the successful first firing cycle at cold-start is also presented in this paper. (author)
[en] The efficiency of each drives is dependent on many factors. Hybrid drives and specially the drives of urban public transport may be affected by other factors given by transport infrastructure or operational conditions. These factors condition the suitable configuration of the individual elements of hybrid drive and the establishment of good control strategy of such drive. The study of influencing factors of the control strategy is the aim of this paper. (full text)
[en] Comparative exergy models for naturally aspirated gasoline and hydrogen fuelled spark ignition internal combustion engines were developed according to the second laws of thermodynamics. A thorough graphical analysis of heat transfer, work, thermo mechanical, and intake charge exergy functions was made. An irreversibility function was developed as a function of entropy generation and graphed. A second law analysis yielded a proportional exergy distribution as a fraction of the intake charge exergy. It was found that the hydrogen fuelled engine had a greater proportion of the intake charge exergy converted into work exergy, indicating a second law efficiency of 50.13% as opposed to 44.34% for a gasoline fuelled engine. The greater exergy due to heat transfer or thermal availability associated with the hydrogen fuelled engine is postulated to be a part of the reason for decreased work output of a hydrogen engine. Finally, a second law analysis of both hydrogen and gasoline combustion reactions indicate a greater combustion irreversibility associated with gasoline combustion. A percentage breakdown of the combustion irreversibilities were also constructed according to information found in literature searches. (author)
[en] The paper presents a model of fixed and variable geometry turbines. The aim of this model is to provide an efficient boundary condition to model turbocharged internal combustion engines with zero- and one-dimensional gas dynamic codes. The model is based from its very conception on the measured characteristics of the turbine. Nevertheless, it is capable of extrapolating operating conditions that differ from those included in the turbine maps, since the engines usually work within these zones. The presented model has been implemented in a one-dimensional gas dynamic code and has been used to calculate unsteady operating conditions for several turbines. The results obtained have been compared with success against pressure-time histories measured upstream and downstream of the turbine during on-engine operation