温度对乙醇重整燃料发动机充气效率的影响

一种简化计算公式能够描述进气温度变化对内燃机充气效率的影响。同时采用工作过程仿真和笔者提出的计算公式比较,考虑了发动机负荷、转速、发动机排量、进气入口空气温度和乙醇重整燃料温度等因素,计算分析了温度对乙醇重整燃料发动机充气效率的影响。简化计算公式的计算结果与工作过程仿真的计算结果非常接近,二者的最大差值小于0.5%;计算结果表明,由于高温乙醇重整燃料引起的进气温度变化,导致充气效率下降3%~7%。     

测量多缸内燃机单缸充气效率的压力波方法

提出了一种按准稳定流动处理方法，利用实测多缸内燃机进气门前后的压力波间接测量多缸内燃机单缸充气效率。利用奥地利AVL657内燃机数据采集分析仪等测试设备，通过测量和计算获得了各缸各工况下的进气充量和充气效率，并将测量结果与实测多缸内燃机平均充气效率进行了比较，充气效率值最大相差0．03，考察了该方法的可行性。得到的实验内燃机充气效率不均匀度值最大相差8．9％，用这种方法可以定量研究多缸机各缸进气充量的均匀性。     

基于空气动力循环的内燃机废气余热回收方法

为提高内燃机能量利用效率,提出了采用布雷顿空气循环回收内燃机废气余热能的底循环方案,并对其回收废气余热能的潜力进行了研究。针对不同的循环压力、循环空气流量和内燃机排气温度进行了循环多参数性能计算分析,得出该余热回收系统循环参数和内燃机排气温度对废气余热能回收效率的影响。研究结果表明:循环压力和空气流量范围受内燃机排气温度制约,排气温度越高,可用压力范围和空气流量范围越大,并且相应的回收效率也越高;分别存在一个最佳压力点和一个最佳空气流量点,使回收效率出现峰值。     

内燃机和燃气轮机在发电领域的比较

从油耗、温度、部分负荷以及海拔高度对原动机的影响等方面 ,对内燃机和燃汽轮机的功率与效率进行了比较。实践证明 ,在上述条件下 ,内燃机比燃气轮机更优越 ,同时受燃料价格波动影响也较小。     

点燃式内燃机气体燃料电控喷射技术的研究

气体燃料被认为是很有前途的车用低污染代用燃料。本文对气体燃料进气门电控喷射技术进行了研究，研制了气体燃料喷射系统、电子点火系统和发动机控制系统，对空燃比、压缩比和充气系数等参数对发动机性能的影响进行了试验与分析。     

新型内燃机

热机的输入端与输出端介质温差越大，则热机效率就越高。这一热力学定律迫使热机设计人员设法提高燃烧温度。例如内燃机发明者狄塞尔使气缸中的燃料在高压下点燃，因此使内燃机效率比蒸汽机大大提高。但是内燃机排气的温度仍然比蒸汽机管道排出的蒸汽温度要高，因此提高内燃机效率的潜力还没有用尽。     

乙醇重整燃料对内燃机充气效率的影响

提出乙醇重整燃料对发动机充气效率的影响的计算公式,可以预测完全燃用或者部分掺烧乙醇重整燃料对SI发动机充气效率和柴油机充气效率的影响。计算分析结果表明：乙醇重整燃料影响充气效率的主要因素是乙醇浓度和重整率,随着重整率的增加,乙醇重整发动机的充气效率有较大幅度下降,必将导致发动机的动力性能急剧下降,柴油机部分掺烧乙醇重整燃料对充气效率的影响较小。     

国内燃气发动机现状

本文介绍了国内可以用于内燃机的气体燃料,国内外燃气内燃机在国内的应用情况,以及所需的技术等.     

柴油机充气效率的预测模型

充气效率是评价内燃机换气过程完善程度的一个重要指标,它随发动机转速的变化关系称为充气特性。改善充气特性是提高柴油机动力性的一个重要措施。在预测充气效率或优化进气系统时,需要建立一个充气效率的预测模型。本文利用实测的进、排气压力波(也可以用计算的压力波),考虑气门边界与缸内的能量方程,建立了一     

吸收式热泵回收烟气冷凝热的实验研究

基于清华大学超低能耗示范楼热电冷联供平台,对利用吸收式热泵回收天然气烟气冷凝热进行了实验研究,分析了余热回收系统的开启、变工况和关机动态响应过程.实验表明,烟气余热回收系统的开启过程较长,应尽量使内燃机与热泵的容量匹配,缩短开机时间;内燃机发电功率对系统供热功率和供热温度影响较大,对冷凝热回收功率、冷冻水温度和制热COP影响较小;系统供热温度对热泵性能影响较大;应选择合适的关机模式,以保证系统安全、缩短关机时间.     

气体燃料燃烧特性分析计算与软件开发及应用

气体燃料是发动机的燃料之一,燃料种类繁多、组分不同,没有统一标准。用于燃气机必定对燃气机各项经济技术指标、结构设计有不同的要求,如何对各种气体燃料燃烧特性进行分析及评价,是燃气机设计首先要解决的问题。本文对各种气体燃料的燃烧特性进行了分析、计算,并开发了计算机分析计算软件,作为燃气机设计时参考。     

生物质应用于制液体和气体燃料而不是用于发电

我国能源结构从长期看仍将以煤为主,缺油少气。从我国能源结构来讲,生物质利用的最好方式不是发电．因生物质可以生产液体和气体燃料,而风能、太阳能、水能却只能发电。我国秸杆综合利用取得明显成效．在农业和畜牧业的利用领域还可能进一步拓宽,作为燃料利用的量还可能进一步缩减。从我国还在进行的第一次能源大转换来看,我国生物质使用量已大大减少,但还有相当的数量。要减少作为能源使用的生物质传统利用量,把它用于饲料、肥料和工业原料等还有发展前景的用途。在一次能源消费以化石能源为主的时期,中国存在液体燃料和气体燃料短缺的问题,以后进入第三次能源转换时期,新能源和可再生能源替代化石能源之后,液体燃料和气体燃料短缺的问题将会更加突出。因此,生物质应用于生产液体燃料和气体燃料,而不是用于发电。而且生物质发电厂投资高、燃料成本不断上涨,使发电成本高＋生物质发电将长期缺乏竞争力。我国发展生物质液体燃料已具备一定的条件．前几年中石油、中石化和中海油已开始种植可提炼生物液体燃料的能源林。我国非粮生物质液体燃料生产基地正在积极建设之中。我国发展生物质气体燃料也具有一定优势,在沼气、气化和城镇有机废物处理方面都积累了一定的经验。总之生物质生产液体燃料和气体燃料是一种既适应我国当前、又适应未来能源需求的有效措施。     

Comparative energies of alternative fuels

In order to provide additional design data on candidate alternative fuels, a broad comparison is made of the net calorific values of a wide variety of gaseous, liquid and solid fuels, including a number of alternatives of current interest, against a background of conventional fuels, some of which may have alternative applications.In general, higher gravimetric calorific values are shown by the lighter of the gaseous and liquid fuels and the heavier of the solid fuels. Volumetric calorific values rise with fuel density, with the exception of the fuel gases. Despite a wide overall range in calorific values, the gravimetric energy content of a stoichiometric fuel-air mixture is seen to be virtually independent of fuel type. In such applications as the spark-ignition piston engine and the rocket, additional combustion parameters arise which tend to overshadow calorific value and are therefore adopted for performance assessment.     

Experimental investigation concerning the effect of natural gas percentage on performance and emissions of a DI dual fuel diesel engine

During the last years a great effort has been made to reduce pollutant emissions from direct injection (DI) diesel engines. Towards this, engineers have proposed various solutions, one of which is the use of gaseous fuels as a supplement for liquid diesel fuel. These engines, which use conventional diesel fuel and gaseous fuel, are referred to as dual fuel engines. The main aspiration from the usage of dual fuel (liquid and gaseous one) combustion systems is mainly to reduce particulate emissions and nitrogen oxides.One of the gaseous fuels used is natural gas, which has a relatively high auto ignition temperature and moreover is an economical and clean burning fuel. The high auto ignition temperature of natural gas is a serious advantage against other gaseous fuels since the compression ratio of most conventional DI diesel engines can be maintained. Moreover the combustion of natural gas produces practically no particulates since natural gas contains less dissolved impurities (e.g. sulfur compounds).The present contribution is mainly concerned, with an experimental investigation of the characteristics of dual fuel operation when liquid diesel is partially replaced with natural gas under ambient intake temperature in a DI diesel engine. Results are given revealing the effect of liquid fuel percentage replacement by natural gas on engine performance and emissions.     

Oxy-hydrogen gas as an alternative fuel for heat and power generation applications - A review

One of the important goals in today's world is sustainable power generation by using low or zero polluting fuels and energy conversion devices. In this context, utilization of gaseous fuels in internal combustion (IC) engines is focused more due to their better fuel mixing ability with air, higher combustion efficiency, easier transportation, and lower pollutant formation. Liquefied petroleum gas (LPG), compressed natural gas (CNG), hydrogen, and biogas are considered as commonly available alternative gaseous fuels for IC engines. Yet, a search for other possible alternative gaseous fuels is continuing in the world. In recent years, Oxy-hydrogen (HHO) also known as Brown's gas has been explored by many researchers in the world, for the possibility of using it for heat and power applications. Because of this, a comprehensive review of the production of HHO using different generators and its utilization in heat and power applications has been carried out, and the discussions are presented in this paper.     

Simultaneous production of gaseous fuels with degradation of Rhodamine B using a 40 kHz double-bath-type sonoreactor

This work proposed a novel double-bath-type sonoreactor to demonstrate the possibility of applying ultrasound power for simultaneous production of gaseous fuels with degradation of Rhodamine B (RhB). The developed double-bath-type sonoreactor allows concentrating the energy of the ultrasonic waves to a limited region and, consequently allows the acoustic intensity in there to be increased approximately 30-fold compared to that can be created in a normal ultrasonic bath at the same applied power. The effect of acoustic intensity, temperature of water bath, static and bubbling argon atmosphere, initial RhB concentration, and dissolved gases on the sonochemical activity both in terms of RhB degradation and gaseous fuel productions were fully investigated. The possible pathways for the simultaneous production of gaseous fuels with degradation of RhB were elucidated. Sonochemical degradation of RhB was successfully analysed by Langmuir-Hinshelwood-type kinetics.     

气体燃料再燃对NOx还原的影响

气体燃料再燃是研究较多的降低烟气中ＮＯｘ含量最有效的方法之一。本文以典型的一次燃烧区烟气成分为模拟烟气,研究了不同的气体燃料（ＣＨ４,Ｃ２Ｈ２和Ｃ２Ｈ４）作为再为燃烧料时,再燃区燃烧工况（空气过量系数和再燃温度）对ＮＯｘ再燃过程和ＮＯｘ还原率的影响。通过计算发现,不同组分的气体燃料、再燃区空气过量系数及再燃区对ＮＯｘ的再燃过程和ＮＯｘ还原率都有重要的影响。     

Effect of engine parameters and type of gaseous fuel on the performance of dual-fuel gas diesel engines—A critical review

Petroleum resources are finite and, therefore, search for their alternative non-petroleum fuels for internal combustion engines is continuing all over the world. Moreover gases emitted by petroleum fuel driven vehicles have an adverse effect on the environment and human health. There is universal acceptance of the need to reduce such emissions. Towards this, scientists have proposed various solutions for diesel engines, one of which is the use of gaseous fuels as a supplement for liquid diesel fuel. These engines, which use conventional diesel fuel and gaseous fuel, are referred to as ‘dual-fuel engines’. Natural gas and bio-derived gas appear more attractive alternative fuels for dual-fuel engines in view of their friendly environmental nature. In the gas-fumigated dual-fuel engine, the primary fuel is mixed outside the cylinder before it is inducted into the cylinder. A pilot quantity of liquid fuel is injected towards the end of the compression stroke to initiate combustion. When considering a gaseous fuel for use in existing diesel engines, a number of issues which include, the effects of engine operating and design parameters, and type of gaseous fuel, on the performance of the dual-fuel engines, are important. This paper reviews the research on above issues carried out by various scientists in different diesel engines. This paper touches upon performance, combustion and emission characteristics of dual-fuel engines which use natural gas, biogas, producer gas, methane, liquefied petroleum gas, propane, etc. as gaseous fuel. It reveals that ‘dual-fuel concept’ is a promising technique for controlling both NO_x and soot emissions even on existing diesel engine. But, HC, CO emissions and ‘bsfc’ are higher for part load gas diesel engine operations. Thermal efficiency of dual-fuel engines improve either with increased engine speed, or with advanced injection timings, or with increased amount of pilot fuel. The ignition characteristics of the gaseous fuels need more research for a long-term use in a dual-fuel engine. It is found that, the selection of engine operating and design parameters play a vital role in minimizing the performance divergences between an existing diesel engine and a ‘gas diesel engine’.     

Advanced tubular solid oxide fuel cells with high efficiency for internal reforming of hydrocarbon fuels

Solid oxide fuel cells (SOFCs) constitute an attractive power-generation technology that converts chemical energy directly into electricity while causing little pollution. NanoDynamics Energy (NDE) Inc. has developed micro-tubular SOFC-based portable power generation systems that run on both gaseous and liquid fuels. In this paper, we present our next generation solid oxide fuel cells that exhibit total efficiencies in excess of 60% running on hydrogen fuel and 40+% running on readily available gaseous hydrocarbon fuels such as propane, butane etc. The advanced fuel cell design enables power generation at very high power densities and efficiencies (lower heating value-based) while reforming different hydrocarbon fuels directly inside the tubular SOFC without the aid of fuel pre-processing/reforming. The integrated catalytic layered SOFC demonstrated stable performance for >1000 h at high efficiency while running on propane fuel at sub-stoichiometric oxygen-to-fuel ratios. This technology will facilitate the introduction of highly efficient, reliable, fuel flexible, and lightweight portable power generation systems.