Comparative first- and second-law parametric study of transient diesel engine operation

A computer model is developed for studying the first- and second-law (availability) balances of a turbocharged diesel engine, operating under transient load conditions. Special attention is paid to the direct comparison between the results from the two laws, for various operating parameters of the engine. The model simulates the transient operation on a degree crank angle basis, using a detailed analysis of mechanical friction, a separate consideration for the processes of each cylinder during a cycle (“multi-cylinder” model) and a mathematical model of the fuel pump. Experimental data taken from a marine duty, turbocharged diesel engine, located at the authors’ laboratory, are used for the evaluation of the model's predictive capabilities. The first-law (e.g., engine speed, fuel pump rack position, engine load, etc.) and second-law (e.g., irreversibilities, heat loss and exhaust gases) terms for the diesel engine cylinder are both computed and depicted in comparison, using detailed diagrams, for various engine operating parameters. It is revealed that, at least for the specific engine type and operation, a thermodynamic, dynamic or design parameter can have a conflicting impact on the engine transient response as regards energy and availability properties, implying that both a first- and second-law optimization is needed for best performance evaluation.     

内燃机部分零部件故障分析

内燃机是由数以干计的零部件构成的精密复杂机械,内燃机中的每种零部件都有各自的功能,在使用中一旦失效,内燃机便不能可靠、经济的运行。活塞、活塞环、活塞销、气缸套、气门、轴瓦是内燃机的关键零部件,它们在高温、高压和剧烈摩擦的恶劣条件下工作,如果安装、使用、维护不当或自身存在缺陷,极易在运行中出现故障和损伤。     

内燃机飞轮的模态分析

利用ANSYS对飞轮进行模态分析,采用ANSYS软件模态分析模块中的BLOCKLANC—ZOS方法进行模态计算,得到飞轮的前6阶固有频率及其对应的振型,并利用ANSYS软件分别计算出了用铸钢和铸铁制造的飞轮各阶模态对应的临界转速。     

A combustion model for IC engine combustion simulations with multi-component fuels

Reduced chemical kinetic mechanisms for the oxidation of representative surrogate components of a typical multi-component automotive fuel have been developed and applied to model internal combustion engines. Starting from an existing reduced mechanism for primary reference fuel (PRF) oxidation, further improvement was made by including additional reactions and by optimizing reaction rate constants of selected reactions. Using a similar approach to that used to develop the reduced PRF mechanism, reduced mechanisms for the oxidation of n-tetradecane, toluene, cyclohexane, dimethyl ether (DME), ethanol, and methyl butanoate (MB) were built and combined with the PRF mechanism to form a multi-surrogate fuel chemistry (MultiChem) mechanism. The final version of the MultiChem mechanism consists of 113 species and 487 reactions. Validation of the present MultiChem mechanism was performed with ignition delay time measurements from shock tube tests and predictions by comprehensive mechanisms available in the literature.A combustion model was developed to simulate engine combustion with multi-component fuels using the present MultiChem mechanism, and the model was applied to simulate HCCI and DI engine combustion. The results show that the present multi-component combustion model gives reliable performance for combustion predictions, as well as computational efficiency improvements through the use of reduced mechanism for multi-dimensional CFD simulations.     

内燃机活塞优化设计及分析

利用PRO／E软件,运用有限元分析技术,详细分析内燃机活塞负荷的基础上,提出活塞的机械负荷边界条件,经多次拟合修正,计算得到活塞的机械应力。计算结果显示原设计活塞有较大的储备强度,有进一步优化的可能。通过有限元分析设计改进后的活塞减小了压缩高度,降低了质量,使活塞结构更趋合理。有限元分析表明,各种应力应变均在设计允许范围之内,活塞结构的改进是成功的设计。     

内燃机代用燃料的发展分析

指出与说明了代用燃料的定义、分类、选择以及使用标准,概述了内燃机代用燃料的发展历史和研究现状,总结了国内外内燃机代用燃料的发展与应用动态。指出由于石油资源的日益减少,代用燃料是今后能源应用与研究的方向。     

Energy and exergy analysis of a turbocharged hydrogen internal combustion engine

This paper has analyzed the energy and exergy distribution of a 2.3 L turbocharged hydrogen engine by mapping characteristics experiment. The energy loss during fuel energy conversion mainly includes: exhaust energy (23.5–34.7%), cooling medium (coolant and oil) energy (21.3–34.8%), intercooler energy (0.5–3.6%) and uncounted energy (5.8–14.1%), while the proportion of effective work ranges from 25.7% to 35.1%. Results show that all kinds of energies increase with engine speeds and they are not sensitive to the loads. However, the proportions of different kind of energy exhibit different characteristics. Moreover, the turbocharger can increase the brake thermal efficiency and the maximum can be increased by 4.8%. Exergy analysis shows exergy efficiency of the coolant energy does not exceed 5%, while the exergy efficiency of the exhaust energy can reach up to 23%. And the total hydrogen fuel thermal efficiency limit is theoretically above 59%.     

High-efficiency internal combustion engine for hybrid hydrogen-electric locomotives

Hydrogen electric locomotives are receiving growing attention and progressing towards net zero. This letter discusses the improvement of traditional diesel-electric locomotives to use hydrogen and reduce energy demand. An internal combustion engine featuring direct injection and jet ignition of the hydrogen is proposed. The four-strokes, 12 L, V12 engine achieves peak power of 750 kW and peak efficiency above 46%. The propulsion system may be further optimized by adopting battery energy storage to buffer the operation of the engine and provide extra power when accelerating. This way, the engine may be further optimized to work over a narrower range of speeds and loads and be made smaller to provide reduced power.     

富氧燃烧对不同气体燃料特性的对比分析

为有效利用工业副产煤气,改善锅炉低负荷稳定燃烧,现针对某动力厂燃气锅炉运行过程中水平烟道氧含量不满足运行条件的情况,采用助燃空气富氧燃烧方案,分析高炉煤气、转炉煤气和按9∶1比例混合出的混合煤气经助燃空气富氧后对烟道氧含量及其燃烧特性的影响。结果表明:助燃空气富氧增容后,排烟量与空气量均减少;转炉煤气、混合煤气以及高炉煤气在送风量不变的情况下,助燃空气分别富氧增容至27%、29%、33%时,可提高锅炉水平烟道氧含量,使其达到2%左右。燃气锅炉采用助燃空气富氧燃烧的技术方案,在实现工业副产有效利用的同时,极大程度地减少了污染物的排放。     

Preparation,characterization, engine combustion and emission characteristics of rapeseed oil based hybrid fuels

In this study, hybrid fuels consisting of rapeseed oil/diesel blend, 1% aqueous ethanol and a surfactant (oleic acid/1-butanol mixture) were prepared and tested as a fuel in a direct injection (DI) diesel engine. The main fuel properties such as the density, viscosity and lower heating value (LHV) of these fuels were measured, and the engine performance, combustion and exhaust emissions were investigated and compared with that of diesel fuel. The experimental results showed that the viscosity and density of the hybrid fuels were decreased and close to that of diesel fuel with the increase of ethanol volume fraction up to 30%. The start of combustion was later than that of diesel fuel and the peak cylinder pressure, peak pressure rise rate and peak heat release rate were higher than those of diesel fuel. The brake specific fuel consumption (BSFC) of hybrid fuels was increased with the volume fraction of ethanol and higher than that of diesel. The brake specific energy consumption (BSEC) was almost identical for all test fuels. The smoke emissions were lower than those for diesel fuel at high engine loads, the NO_x emissions were almost similar to those of diesel fuel, but CO and HC emissions were higher, especially at low engine loads.     

The production of hydrogen through the uncatalyzed partial oxidation of methane in an internal combustion engine

The thermodynamic and kinetic limitations of the uncatalyzed partial oxidation of methane for the production of synthesis gas, which is made up of mostly hydrogen and carbon monoxide in a variety of proportions, are reviewed. It is suggested that such processes can be made to proceed successfully in a conventional internal combustion engine when operated on excessively rich mixtures of methane and oxygenated air. This is achieved while simultaneously producing power and regenerative exhaust gas heating.     

Effect of Diesel/methanol compound combustion on Diesel engine combustion and emissions

This paper introduces a Diesel/methanol compound combustion system (DMCC) and its application to a naturally aspirated Diesel engine with and without an oxidation catalytic converter. In the DMCC system, there are two combustion modes taking place in the Diesel engine, one is diffusion combustion with Diesel fuel and the other is premixed air/methanol mixture ignited by the Diesel fuel. Experiments were conducted on a four cylinder DI Diesel engine, which had been modified to operate in Diesel/methanol compound combustion. Experiments were conducted at idle and at five engine loads at two levels of engine speeds to compare engine emissions from operating on pure Diesel and on operating with DMCC, with and without the oxidation catalytic converter. The experimental results show that the Diesel engine operating with the DMCC method could simultaneously reduce the soot and NOx emissions but increase the HC and CO emissions compared with the original Diesel engine. However, using the DMCC method coupled with an oxidation catalyst, the CO, HC, NOx and soot emissions could all be reduced.     

An onboard hydrogen generator for hydrogen enhanced combustion with internal combustion engine

Hydrogen enhanced combustion (HEC) for internal combustion engine is known to be a simple mean for improving engine efficiency in fuel saving and cleaner exhaust. An onboard compact and high efficient methanol steam reformer is made and installed in the tailpipe of a vehicle to produce hydrogen continuously onboard by using the waste heat of the engine for heating up the reformer; this provides a practical device for the HEC to become a reality. This use of waste heat from engine enables an extremely high process efficiency of 113% to convert methanol (8.68 MJ) for 1.0 NM of hydrogen (9.83 MJ) and low cost of using hydrogen as an enhancer or as a fuel itself. The test results of HEC from the onboard hydrogen production are presented with 2 gasoline engine vehicles and 2 diesel engines; the results indicate a hike of engine efficiency in 15–25% fuel saving and a 40–50% pollutants reduction including 70% reduction of exhaust smoke. The use of hydrogen as an enhancer brings about 2–3 fold of net reductions in energy, carbon dioxide emission and fuel cost expense over the input of methanol feed for hydrogen production.     

内燃机活塞环材料及其表面处理

活塞环在发动机中起着密封、控油、导热、支撑的作用，活塞环材料应具备良好的耐磨性、耐热性、耐蚀性、强韧性、导热性、工艺制造性以及与气缸材料的磨合性。球墨铸铁和钢材已经成为活塞环的基本材料，采用表面处理方法如镀铬、氮化、喷钼、喷涂陶瓷层等工艺进行表面改性来提高活塞环的使用性能。需要不断地研究和开发新型活塞环材料和表面处理工艺来满足发动机的发展需要。     

Catalytic steam reforming of methane,methanol, and ethanol over Ni/YSZ: The possible use of these fuels in internal reforming SOFC

This study investigated the possible use of methane, methanol, and ethanol with steam as a direct feed to Ni/YSZ anode of a direct internal reforming Solid Oxide Fuel Cell (DIR-SOFC). It was found that methane with appropriate steam content can be directly fed to Ni/YSZ anode without the problem of carbon formation, while methanol can also be introduced at a temperature as high as 1000 °C. In contrast, ethanol cannot be used as the direct fuel for DIR-SOFC operation even at high steam content and high operating temperature due to the easy degradation of Ni/YSZ by carbon deposition. From the steam reforming of ethanol over Ni/YSZ, significant amounts of ethane and ethylene were present in the product gas due to the incomplete reforming of ethanol. These formations are the major reason for the high rate of carbon formation as these components act as very strong promoters for carbon formation.     

The distinctive characteristics of combustion duration in hydrogen internal combustion engine

As a practical solution to reduce the emission pollution and energy crisis, the research and development of HICE has been processed in several decades. The focus of this paper is trying to explore the new features of the combustion duration in HICE not only by engine experiment, but also by analysis of the physical properties of hydrogen, especially the obvious difference from that of gasoline. Firstly, the laminar flame speed difference between hydrogen and gasoline was studied and discussed. Secondly, a distinctive rule of combustion duration in HICE was discovered by analyzing the experiment data. Finally, as a key reference point to the HICE operation, a new characteristic of the location of 50% mixture combust up was proposed and analyzed, this will be helpful for the calibration of optimum ignition timing.     

工程陶瓷材料在内燃机上的应用

参考了国内外有关内燃机新材料应用方面的最新资料,综合介绍了陶瓷材料应用于内燃机零件的发展动态,探讨了陶瓷材料的应用障碍及发展前景.     

内燃机冷热电联产系统设计点性能分析

简介内燃机冷热电联产系统的发展现状,总结了发电用内燃机在设计点工况下主要参数的现有分布范围:排气温度约为450~600℃,排气流量基本上与额定功率呈线性关系,发电效率一般在33%~45%。对联产系统不同形式的能量输出、联产系统经济效率等进行分析研究,表明联产系统回收的能量主要来自排气和冷却水,排气回收能量一般高于冷却水回收能量。与热电联产系统相比,由于制冷比供热困难,冷热电联产系统的经济效率较高。     

Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines

The increasing industrialization and motorization of the world has led to a steep rise for the demand of petroleum-based fuels. Petroleum-based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain regions of the world. Therefore, those countries not having these resources are facing energy/foreign exchange crisis, mainly due to the import of crude petroleum. Hence, it is necessary to look for alternative fuels which can be produced from resources available locally within the country such as alcohol, biodiesel, vegetable oils etc. This paper reviews the production, characterization and current statuses of vegetable oil and biodiesel as well as the experimental research work carried out in various countries. This paper touches upon well-to-wheel greenhouse gas emissions, well-to-wheel efficiencies, fuel versatility, infrastructure, availability, economics, engine performance and emissions, effect on wear, lubricating oil etc.     

Performance analysis of a novel eco‐friendly internal combustion engine cycle

The Miller cycle applications have been performed to diminish NO_x released from internal combustion engines (ICEs), in recent years. The Miller cycle provides decreased compression ratio and enhanced expansion ratio; hereby, maximum in‐cylinder combustion temperatures diminish, and NO_x formations slow down remarkably. Another less‐known method is Takemura cycle application, which provides heat addition into engine cylinder at constant combustion temperatures. In this study, a novel cycle including the Miller cycle and the Takemura cycle has been developed by using novel numerical models and computing methods with seven processes and a novel way to decrease NO_x emissions at higher levels compared with the single applications of known cycles. A comprehensive performance examination of the proposed cycle engine in terms of performance characteristics such as effective power (EFP), effective power density (EFPD), exergy destruction (X), exergy efficiency (ε), and ecological coefficient of performance (ECOP) has been conducted. The impacts of engine operating and design parameters on the performance characteristics have been computationally examined. Furthermore, irreversibilities depending on incomplete combustion loss (INCL), exhaust output loss (EXOL), heat transfer loss (HTRL), and friction loss (FRL) have been considered in the performance simulations. The minimum exergy destruction and maximum performance specifications have been observed with 30 of the compression ratio. Maximum effective power values have been obtained at range between 1 and 1.2 of equivalence ratio. The optimum range for exergy efficiency is between 0.8 and 1 of equivalence ratio. Increasing engine speed has provided enhancing effective power. However, an optimum range has been found for the exergy efficiency that is interval of 3000 to 4000 rpm. The results obtained can be assessed by researchers studying on modeling of the engine systems and designs.