水冲压发动机用金属燃料的研究进展

介绍了用于超高速鱼雷的巡航动力推进系统——水冲压发动机的基本原理，阐述了水反应金属燃料的组成及特点，以金属镁与水在不同状态下的反应机理为例对水反应金属燃料的工作原理进行了分析。并提出燃料的组织形式、点火技术和燃烧性能调节技术等是水反应金属燃料研究中的关键技术。通过总结国内外水冲压发动机及水反应金属燃料的研究进展，指出国内相关领域研究的不足和发展方向。附参考文献22篇。     

国外鱼雷热动力推进剂应用与发展趋势

简要介绍了国外鱼雷热动力推进剂的种类和能量密度,详细综述了柴油(煤油)/H_2O_2、OTTO-Ⅱ、HAP(高氯酸羟胺)/OTTO-Ⅱ/海水、水反应金属燃料等鱼雷热动力推进剂的性能及应用,并展望了鱼雷热动力推进剂未来发展趋势。     

二维金属有机框架及其衍生物用于电催化分解水的研究进展

氢能是一种具有发展前景的可再生清洁能源，电催化分解水是产生氢气的有效途径，设计高效、经济的分解水电催化剂对促进可再生能源的发展至关重要。二维金属有机框架材料（MOFs）具有独特的二维层状结构和灵活可调的化学组成，近年来被广泛应用于电催化分解水领域。二维金属有机框架材料可进一步衍生形成氧化物、磷化物、硫化物、金属-碳复合物等材料，也表现出良好的电催化分解水性能。通过组分调节和结构调控能有效地优化二维金属有机框架及其衍生的材料的本征活性和反应动力学特性，进而提高其电催化性能。此综述介绍了二维MOFs材料及其衍生物在电催化水分解领域的最新研究进展，并展望了其未来研究方向和发展空间。     

基于水反应实验的动力学设计

水作为人们日常生活、工业生产中的重要载体。通过水体与金属物质的反应,可生成其他能源物质,可进一步替代不可再生资源,实现社会能源的可持续供给。基于此,以铝材料与水反应为基础,解析纳米铝粉与水反应的特性,并对水反应实验支持下的动力学设计进行研究。     

甲醇燃料作为发动机新型潜代能源存在问题及应对策略探讨

针对石油资源日趋减少的能源危机问题,研究分析甲醇燃料作为发动机新型潜能源的可行性。通过分析现有甲醇燃料作为新型潜代能源的优势,探讨甲醇燃料作为发动机新型潜用能源存在的问题及应对策略。综合对比分析得出,甲醇燃料在众多潜用燃料中作为发动机新型潜代能源具备极好的优越性和可行性,为甲醇燃料发动机的进一步研究提供参考。     

醇汽油混合燃料的应用研究

能源短缺和环境保护双重压力使得醇类燃料的应用研究日益突出。从应用分析的角度,通过发动机台架试验,研究了M30、M50、E10对发动机动力性、经济性及排放性能的影响,并与93#汽油进行了对比分析,而在试验过程中发动机的结构参数未作任何调整。     

浅析硫化学应用前景

硫元素，是近代化学工业和现代化学工业紧密相关的最重要元素之一。生命体内，硫元素主要以含硫巯基的氨基酸和多肽的形式存在，是蛋白质和其他生物分子的重要组成部分，因此广泛应用于医药、食品和精细化工等领域；化工生产中，硫元素广泛用于橡胶、纸浆、玻璃、石油加工和金属提取等领域，含硫化合物在石油、煤炭等化石燃料的加工过程中具有重要作用；能源领域，硫参与了生物质能源、光催化水分解等研究，如硫掺杂碳材料被广泛用于锂离子电池、超级电容器、传感器等领域。硫元素和含硫化合物在人类社会的发展中具有广泛应用性，对社会经济产生了深远的影响。     

汽车代用燃料的开发

为减少对不可再生石油能源的过度开采和环境污染 ,用于汽车的许多种代用燃料已经被开发出来 ,主要有压缩天然气、液化石油气、醇燃料、合成燃料、二甲醚、生物柴油、氢及燃料电池等。压缩天然气和液化石油气是较好的代用燃料 ,将会被大量应用 ;醇燃料是清洁燃料 ,但当要避免甲醇的毒性问题时 ,乙醇可代替 ;合成燃料有两种 ,一种是合成气经费 托反应制取液体燃料 ,另一种是通过煤液化反应制取 ;二甲醚和氢制备方法较成熟 ,均是清洁燃料 ,适用不同的发动机 ;生物柴油以天然植物油为原料 ,有环保和润滑特性 ,但高粘度影响了它的应用 ;燃料电池…     

镁/铝合金水反应金属燃料推进剂的燃烧性能

通过高能球磨工艺制备了高活性球磨镁/铝合金粉,并制备了两组镁/铝基水反应金属燃料推进剂,用固体推进剂燃速测试系统测定了其燃速。采用氧弹量热仪测定了推进剂的爆热值,并收集推进剂的一次燃烧固相产物,将其放置于水蒸汽高温管式炉中模拟二次燃烧。采用SEM、XRD及化学分析方法表征了水反应金属燃料的一、二次燃烧固相产物。结果表明,高活性球磨镁/铝合金水反应金属燃料推进剂具有更高的燃速和爆热值;二次燃烧产物剩余铝含量更低,二次燃烧产物反应更彻底;高活性球磨镁/铝合金能够改善其水反应金属燃料推进剂的一次燃烧效果,可提高其在二次燃烧中铝的燃烧效率。     

铝基合金燃料的研究及其在固体推进剂中的应用进展

为了阐明元素组成和相组成与铝基合金燃料本征特性的关系，分别总结了低沸点金属、低熔点金属和高熔点金属作为合金元素时对理化特征和燃烧特性的影响规律，分析了不同铝基合金燃料点火和燃烧机制的差异。铝基合金燃料在燃烧过程中，存在Al-M_LB的微爆、Al-M_LM中的合金化放热/氧化通道、Al-M_HM中的亚稳相放热等多种燃烧效率提升的机制。从能量提升和燃速调控两方面归纳了铝基合金燃料在固体推进剂中的应用研究概况，指出铝基合金燃料通过理论比冲提升、燃烧效率提升、二相流损失降低和密度提升等途径提高了推进剂的能量性能；铝基合金燃料对推进剂燃速的影响是配方各组分相互作用的结果，调控效果随着配方中的氧化剂、黏合剂成分而发生改变。掌握铝基合金燃料“制备工艺-结构-性能”的关系、解决安全性和长期储存活性降低问题和完善燃速调节机制及燃烧反应释能机理，是铝基合金燃料的设计、应用和性能调控的关键。附参考文献75篇。     

Vegetable oils and animal fats as alternative fuels for diesel engines with dual fuel operation

Vegetable oils and animal fats are applicable as fuels in standard diesel engines after having adapted the fuel system for electronically controlled dual fuel regime oil/fat-fossil diesel. In this contribution, performance and emission characteristics of the engines running on rapeseed oil, lard, or chicken fat are given and compared to those of fossil diesel and fatty acid methyl esters. The results of engine tests of these fuels show a decrease in maximum power and maximum torque in comparison to fossil diesel due to a lower energy content of triacylglycerols. These values are influenced also by a type of the engine used at testing. When compared to fossil diesel, the opacity of oil/fat based fuels is higher for an engine with lower injection pressures while it is lower for an engine with higher injection pressures. The level of both controlled and uncontrolled emissions is low for all tested biofuels and is low also for the reference fossil diesel. The results of performance and emission tests for rapeseed oil containing 3 and 6 vol.% of anhydrous ethanol are comparable to those obtained for pure oil. In this paper, practical experiences based on long-term operation of adapted vehicle fleet fuelled with oil/fat-fossil diesel are mentioned.     

Methyl and ethyl soybean esters as renewable fuels for diesel engines

The primary problems associated with using straight soybean oil as a fuel in a compression ignition internal combustion engine are caused by high fuel viscosity. Transesterification of soybean oil with an alcohol provides a significant reduction in viscosity, thereby enhancing the physical properties of the renewable fuel to improve engine performance. The ethyl and methyl esters of soybean oil with commercial diesel fuel additives revealed fuel properties that compared very well with diesel fuel, with the exception of gum formation, which manifested itself in problems with the plugging of fuel filters. Engine performance using soybean ester fuels differed little from engine performance with diesel fuel. A slight power loss combined with an increase in fuel consumption were experienced with the esters, primarily because of the lower heating value of the esters than for diesel fuel. Emissions for the 2 fuels were similar, with nitrous oxide emissions higher for the esters. Measurements of engine wear and fuel-injection system tests showed no abnormal characteristics for any of the fuels after the 200-hr tests. Engine deposits were comparable in amount, but slightly different in color and texture, with the methyl ester engine experiencing greater carbon and varnish deposits on the pistons. Presented at the American Oil Chemists’ Society meeting, Chicago, May 1983.     

Combustion of n-butanol in a spark-ignition IC engine

Alcohols, because of their potential to be produced from renewable sources and because of their high quality characteristics for spark-ignition (SI) engines, are considered quality fuels which can be blended with fossil-based gasoline for use in internal combustion engines. They enable the transformation of our energy basis in transportation to reduce dependence on fossil fuels as an energy source for vehicles. The research presented in this work is focused on applying n-butanol as a blending agent additive to gasoline to reduce the fossil part in the fuel mixture and in this way to reduce life cycle CO₂ emissions. The impact on combustion processes in a spark-ignited internal combustion engine is also detailed. Blends of n-butanol to gasoline with ratios of 0%, 20%, and 60% in addition to near n-butanol have been studied in a single cylinder cooperative fuels research engine (CFR) SI engine with variable compression ratio manufactured by Waukesha Engine Company. The engine is modified to provide air control and port fuel injection. Engine control and monitoring was performed using a target-based rapid-prototyping system with electronic sensors and actuators installed on the engine [1]. A real-time combustion analysis system was applied for data acquisition and online analysis of combustion quantities. Tests were performed under stoichiometric air-to-fuel ratios, fixed engine torque, and compression ratios of 8:1 and 10:1 with spark timing sweeps from 18° to 4° before top dead center (BTDC). On the basis of the experimental data, combustion characteristics for these fuels have been determined as follows: mass fraction burned (MFB) profile, rate of MFB, combustion duration and location of 50% MFB. Analysis of these data gives conclusions about combustion phasing for optimal spark timing for maximum break torque (MBT) and normalized rate for heat release. Additionally, susceptibility of 20% and 60% butanol-gasoline blends on combustion knock was investigated. Simultaneously, comparison between these fuels and pure gasoline in the above areas was investigated. Finally, on the basis of these conclusions, characteristic of these fuel blends as substitutes of gasoline for a series production engine were discussed.     

Influence of ethanol blends on the combustion performance and exhaust emission characteristics of a four-cylinder diesel engine at various engine loads and injection timings

The aim of this work is to investigate the effect of ethanol blending to diesel fuel on the combustion and exhaust emission characteristics of a four-cylinder diesel engine with a common-rail injection system. The overall spray characteristics, such as the spray tip penetration and the spray cone angle, were studied with respect to the ethanol blending ratio. A spray visualization system and a four-cylinder diesel engine equipped with a combustion and emission analyzer were utilized so as to analyze the spray and exhaust emission characteristics of the ethanol blending diesel fuel. Ethanol blended diesel fuel has a shorter spray tip penetration when compared to pure diesel fuel. In addition, the spray cone angle of ethanol blended fuels is larger. It is believed that the lower fuel density of ethanol blended fuels affects the spray characteristics. When the ethanol blended fuels are injected around top dead center (TDC), they exhibit unstable ignition characteristics because the higher ethanol blending ratio causes a long ignition delay. An advance in the injection timing also induces an increase in the combustion pressure due to the sufficient premixed duration. In a four-cylinder diesel engine, an increase in the ethanol blending ratio leads to a decrease in NO_x emissions due to the high heat of evaporation of ethanol fuel, however, CO and HC emissions increase. In addition, the CO and HC emissions exhibit a decreasing trend according to an increase in the engine load and an advance in the injection timing.     

Combustion and emissions characteristics of compression-ignition engine using dual ammonia-diesel fuel

This study investigated the combustion and emissions characteristics of a compression-ignition engine using a dual-fuel approach with ammonia and diesel fuel. Ammonia can be regarded as a hydrogen carrier and used as a fuel, and its combustion does not produce carbon dioxide. In this study, ammonia vapor was introduced into the intake manifold and diesel fuel was injected into the cylinder to initiate combustion. The test engine was a four-cylinder, turbocharged diesel engine with slight modifications to the intake manifold for ammonia induction. An ammonia fueling system was developed, and various combinations of ammonia and diesel fuel were successfully tested. One scheme was to use different combinations of ammonia and diesel fuel to achieve a constant engine power. The other was to use a small quantity of diesel fuel and vary the amount of ammonia to achieve variable engine power. Under the constant engine power operation, in order to achieve favorable fuel efficiency, the preferred operation range was to use 40-60% energy provided by diesel fuel in conjunction with 60-40% energy supplied by ammonia. Exhaust carbon monoxide and hydrocarbon emissions using the dual-fuel approach were generally higher than those of using pure diesel fuel to achieve the same power output, while NO_x emissions varied with different fueling combinations. NO_x emissions could be reduced if ammonia accounted for less than 40% of the total fuel energy due to the lower combustion temperature resulting in lower thermal NO_x. If ammonia accounted for the majority of the fuel energy, NO_x emissions increased significantly due to the fuel-bound nitrogen. On the other hand, soot emissions could be reduced significantly if a significant amount of ammonia was used due to the lack of carbon present in the combination of fuels. Despite the overall high ammonia conversion efficiency (nearly 100%), exhaust ammonia emissions ranged from 1000 to 3000 ppmV and further after-treatment will be required due to health concerns. On the other hand, the variable engine power operation resulted in relatively poor fuel efficiency and high exhaust ammonia emissions due to the lack of diesel energy to initiate effective combustion of the lean ammonia-air mixture. The in-cylinder pressure history was also analyzed, and results indicated that ignition delay increased with increasing amounts of ammonia due to its high resistance to autoignition. The peak cylinder pressure also decreased because of the lower combustion temperature of ammonia. It is recommended that further combustion optimization using direct ammonia/diesel injection strategies be performed to increase the combustion efficiency and reduce exhaust ammonia emissions.     

Numerical analysis of injection characteristics using biodiesel fuel

This paper deals with numerical analysis of injection process using biodiesel/mineral diesel fuel blends with the aim to search for the potentials to reduce engine harmful emissions. The considered fuels are neat biodiesel from rapeseed oil and its blends with mineral diesel D2. For the numerical analysis a one-dimensional mathematical model is employed. In order to model accurately the investigated fuels, the employed empirical expressions for their properties are determined by experiments. To verify the mathematical model and the empirical expressions, experiments and numerical simulation are run on a mechanical control diesel fuel injection M system at several operating regimes. Injection process at many different operating regimes and using several fuel blends are then investigated numerically. Attention is focused on the injection characteristics, especially on fuelling, fuelling at some stage of injection, mean injection rate, mean injection pressure, injection delay and injection timing, which influence the most important engine characteristics. The analysis of the obtained results reveals that, while keeping engine performance within acceptable limits, harmful emissions can be reduced by adjusting appropriately pump injection timing in dependence on the biodiesel content. This prediction is also confirmed experimentally.     

Stratification of fuel for better engine performance

The concept of fuel stratification has been proposed and applied to a four-valve port injection spark ignition engine. In this engine, two different fuels or fuel components are admitted through two separate inlet ports and stratified into two regions laterally by strong tumble flows. Each stratified region has a spark plug to control the ignition. This engine can operate in the stratified lean-burn mode at part loads when fuel is supplied only to one of the inlet ports. While at high load operation, an improved fuel economy and higher power output are also expected through increased anti-knock features by taking advantage of the superior characteristics of different fuel or fuel components. This is achieved by igniting the lower RON (research octane number) fuel first and leaving the higher RON fuel in the end gas region. In this paper, knock limits of homogenous and different fuel stratification combustion modes at high loads were investigated experimentally. Primary reference fuels (PRF), iso-octane and n-heptane, were used to simulate three fuels of different RON: RON90, RON95 and RON100. The research results show that with stratified fuel components of low and high octane numbers, the knock limit, as defined by the minimum spark advance for knocking combustion, was extended apparently when the lower RON fuel was ignited first. In addition, the knock limit could also be extended by increasing the amount of higher RON fuel. However, igniting first the lower RON fuel in the fuel stratification combustion mode produced little improvement in anti-knock behaviour over the homogeneous combustion of the mixture of those two stratified fuels with an average RON.     

Diesel and rapeseed methyl ester (RME) pilot fuels for hydrogen and natural gas dual-fuel combustion in compression-ignition engines

This paper presents experimental results of rapeseed methyl ester (RME) and diesel fuel used separately as pilot fuels for dual-fuel compression-ignition (CI) engine operation with hydrogen gas and natural gas (the two gaseous fuels are tested separately). During hydrogen dual-fuel operation with both pilot fuels, thermal efficiencies are generally maintained. Hydrogen dual-fuel CI engine operation with both pilot fuels increases NO_x emissions, while smoke, unburnt HC and CO levels remain relatively unchanged compared with normal CI engine operation. During hydrogen dual-fuel operation with both pilot fuels, high flame propagation speeds in addition to slightly increased ignition delay result in higher pressure-rise rates, increased emissions of NO_x and peak pressure values compared with normal CI engine operation. During natural gas dual-fuel operation with both pilot fuels, comparatively higher unburnt HC and CO emissions are recorded compared with normal CI engine operation at low and intermediate engine loads which are due to lower combustion efficiencies and correspond to lower thermal efficiencies. This could be due to the pilot fuel failing to ignite the natural gas-air charge on a significant scale. During dual-fuel operation with both gaseous fuels, an increased overall hydrogen-carbon ratio lowers CO₂ emissions compared with normal engine operation. Power output (in terms of brake mean effective pressure, BMEP) as well as maximum engine speed achieved are also limited. This results from a reduced gaseous fuel induction capability in the intake manifold, in addition to engine stability issues (i.e. abnormal combustion). During all engine operating modes, diesel pilot fuel and RME pilot fuel performed closely in terms of exhaust emissions. Overall, CI engines can operate in the dual-fuel mode reasonably successfully with minimal modifications. However, increased NO_x emissions (with hydrogen use) and incomplete combustion at low and intermediate loads (with natural gas use) are concerns; while port gaseous fuel induction limits power output at high speeds.     

Optimization of a heavy-duty compression-ignition engine fueled with diesel and gasoline-like fuels

Optimal injection strategies for a heavy-duty compression-ignition engine fueled with diesel and gasoline-like fuels (#91 gasoline and E10) and operated under mid- and high-load conditions are investigated. A state-of-the-art engine CFD tool with detailed fuel chemistry was used to evaluate the engine performance and pollutant emissions. The CFD tools feature a recently developed efficient chemistry solver that allowed the optimization tasks to be completed in practical computer times. A Non-dominated Sorting Genetic Algorithm II (NSGA II) was coupled with the CFD tool to seek optimal combinations of injection system variables to achieve clean and efficient combustion. The optimization study identified several key parameters that influence engine performance. It was found that the fuel volatility and reactivity both play important roles at the mid-load condition, while the high-load condition is less sensitive to the fuel reactivity. However, high volatility fuels, such as gasoline and E10, were found to be beneficial to fuel economy at high-load. The study indicates that with an optimized injection system gasoline-like fuels are promising for heavy-duty CI engines due to their lower NOx and soot emissions and higher fuel economy compared to conventional diesel fuels. However, the high in-cylinder gas pressure rise rate associated with Partially Premixed Combustion of gasoline-like fuels can become problematic at high-load and the low-load operating limit is also a challenge. Potential solutions are discussed based on the present optimization results.