浅谈变组分燃料燃烧特性研究进展

以沼气为例分析了变组分燃料对发动机性能的影响，论述了国内外变组分燃料沼气、煤层气和高炉煤气的研究进展，介绍了采用定容燃烧装置和发动机研究变组分燃烧特性的方法，并提出了今后的研究方向。     

一种小型沼气发电机的开发与测试

测试不同天气情况下沼气成分的变化:并以1台加装了新型沼气--空气混合器的汽油机改沼气发动机作为研究对象,研究了点火提前角、火花塞间隙等对沼气发动机运行情况的影响,分析了汽油机改沼气发动机自动熄火的原因,测试了改装后发动机燃烧不同燃料时的运行及尾气排放情况:并对今后沼气发电机的开发提出了建议.     

模拟研究气体燃料发动机燃烧过程的快速压缩膨胀机

将研究柴油机和汽油机的快速压缩膨胀机进行改制，使之可模拟气体燃料发动机中的燃料工将该快速压缩膨胀机用于模拟沼气发动机燃料过程的研究。结果表明：该快速压缩膨胀机可较好地模拟发动机中的燃烧过程，并具有燃烧室结构，工况参数可调等优点。     

LPG／柴油双燃料发动机燃烧产物的分析

研究了LPG/柴油双燃料发动机燃料燃烧时的化学平衡方程,使用Matlab5.3软件编写了LPG/柴油双燃料发动机燃烧产物摩尔分数的分析计算程序,提出了求解双燃料发动机燃烧产物摩尔组分的新方法。计算和实验表明：文中所提的方法是正确和可行的。     

天然气不同组分对车用发动机的排放及性能的影响

基于不同地区不同天然气组分的变化情况,对不同组分的天然气的C/H比、燃料低热值、理论空燃比进行计算与研究.运用GT-power软件建模方式,建立发动机准维燃烧模型,对不同组分的天然气进行燃烧过程分析,以便掌握发动机CO,NO等排放参数及动力性能变化规律,为研制燃烧不同组分天然气的发动机控制算法奠定基础.     

活塞式内燃机燃用沼气的研究

简要介绍了沼气的产生、成分、物理化学性能以及活塞式内燃机燃用沼气可能发生的燃烧速度慢、后燃严重、排气温度高与热负荷大等问题，提出了掺烧和快速全烧两大措施；并相应研制出沼气-柴油双燃料发动机和火花点火全沼气发动机发电机组来适应这两种燃烧方式，取得了较好效果。最后提出将沼气提纯、加压，使其性能接近压缩天然气来作为汽车燃料的方案。     

火花点火沼气发动机的快速燃烧研究与产品开发

沼气燃烧速度慢是造成沼气发动机燃烧持续期长，燃烧效率低，后燃严重，排温高，可靠性与经济性差的根本原因。该文利用快压机对沼气发动机的燃烧过程进行了模拟，提出了改善火花点火沼气发动机性能的快速燃烧方法，设计出了包括燃烧室在内的快速燃烧系统，并将其用于6160沼气发动机发电机组的开发，大大提高了沼气在发动机中的燃烧速度，改善了该沼气发动机可靠性与经济性。     

高辛烷值燃料HCCI燃烧特性的变参数研究

构建了一种高辛烷值燃料与空气压缩自燃反应机理(89种组分,413个反应)。用在快速压缩机上获得的试验数据对它进行了验证,考察了机理的有效性。然后将其嵌入内燃机模型,在CHEMKIN平台上对这种燃料的HCCI燃烧特性进行了变参数的数值模拟,研究了进气温度、进气压力、空燃比、压缩比、转速和EGR等因素对燃烧特性的影响,同时预测了缸内反应物、生成物、自由基浓度随曲轴转角变化的历程。计算结果对燃用高辛烷值燃料HCCI发动机燃烧过程的优化提供了依据。     

发动机燃用煤层气燃料燃烧和排放性能试验研究

在一台单缸火花点火发动机上开展了燃用不同组分配比的煤层气燃料燃烧和排放特性的试验研究,分析了发动机燃用不同组分的煤层气在不同负荷下的缸压、放热率、火焰发展期、主燃烧期及其排放性能.研究结果表明:随着煤层气中氮气体积分数的增加,最高缸内压力和压力升高率降低,燃烧放热率峰值下降,火焰发展期变长,放热率曲线型心对应的曲轴转角偏离上止点;发动机HC和CO排放浓度增大,而NOx排放大幅度下降.     

镁基水反应金属燃料冲压发动机的工作特性

针对水下高速航行器用镁基水反应金属燃料冲压发动机,设定了3种质量组分配比的燃料,结合热力计算和二维轴对称数值模拟研究其工作特性。其中,两进水口处观测到的漩涡预言了在燃料燃烧过程中引发热声振荡的可能性。在3种燃料发动机各自的有效水燃比范围内,通过数值模拟可知两次水燃比的分配直接影响发动机内的燃烧稳定性;总水燃比的增加会引发一个最大的比冲值,同时热效率和推进效率分别单调增加和降低。另外,数值模拟和热力计算结果均显示燃料中镁含量的增加有益于发动机比冲及热效率的增加。本研究中燃烧特性、比冲及效率等工作特性随发动机工况的变化规律特征,可指导发动机整体结构构型及总体性能优化的方向,同时可对发动机内潜在的热声振荡特性进行预估以便设计相应的抑制策略。     

Effect of reformed biogas as a low reactivity fuel on performance and emissions of a RCCI engine with reformed biogas/diesel dual-fuel combustion

Biogas can be used as a less expensive continuance renewable fuel in internal combustion engines. However, variety in raw materials and process of biogas production results in different components and percentages of various elements, including methane. These differences make it difficult to control the combustion, effectively, in internal combustion engines. In this research, under cleaning and reforming process, biogas components were fixed. Then the effect of reformed biogas (R.BG) was investigated, numerically, on the combustion behavior, performance and emissions characteristics of a RCCI engine. A 3D-computational modeling has been performed to validate a single-cylinder compression ignition engine in conventional diesel and dual-fuel operations at 9 bar IMEP, 1300 rpm. Then, the combustion model of the RCCI engine was simulated by replacing diesel fuel with 20%, 40% and 60% of R.BG as a low reactivity fuel while remaining constant input total fuel energy per cycle. The results demonstrated that when the R.BG substitution ratio increases with a constant equivalence ratio of 0.43, the mean combustion temperature decreases to 1354 K, 1312 K, 1292 K which are about 3.5%, 6.6%, 7.9% lower than the conventional diesel combustion, respectively. The maximum in-cylinder pressure increases up to 22.63%. Instead, it results in 2.3%, 7.9%, and 14.5% engine power output losses, respectively. Also, the NOx emission, against CO, is decreased by 50%. Soot and UHC emissions were found to be slightly decreased while was used R.BG more than 40%.     

Biogas (a promising bioenergy source): A critical review on the potential of biogas as a sustainable energy source for gaseous fuelled spark ignition engines

Increasing demand for energy accompanied by environmental concerns has raised the requirement for limiting the use of fossil fuels in energy generation and transportation applications. Among the green and renewable energy-based solutions, biogas is quite promising since it could be implemented for power generation applications (engines driving generators and pump sets) in rural areas, at domestic and industrial scales with lower capital investment and production cost by using the agricultural crop residues and other domestic biomass sources as raw materials. However, the composition of biogas varies depending on the raw materials, and higher concentration of carbon dioxide in biogas results in combustion variations affecting engine durability. This review focuses on the role of biogas in achieving sustainable development goals with an emphasis on its utilization in gaseous fuelled spark-ignited engines. Recent progress in biogas production and upgradation techniques are also detailed. Challenges related to the stability and characteristics of biogas fuelled spark-ignited engines could be addressed by either modifying the physical parameters of the engine or by enhancing the fuel quality (upgradation to biomethane or blending with hydrogen). A comprehensive review on the effects of these approaches on the performance, combustion, and emission characteristics of biogas-fuelled engines is discussed in detail with a note on engine operating parameters.     

Experimental investigation on biogas enrichment with hydrogen for improving the combustion in diesel engine operating under dual fuel mode

Biogas valorization as fuel for internal combustion engines is one of the alternative fuels, which could be an interesting way to cope the fossil fuel depletion and the current environmental degradation. In this circumstance, an experimental investigation is achieved on a single cylinder DI diesel engine running under dual fuel mode with a focus on the improvement of biogas/diesel fuel combustion by hydrogen enrichment. In the present investigation, the mixture of biogas, containing 70% CH₄ and 30% CO₂, is blended with the desired amount of H₂ (up to 10, 15 and 20% by volume) by using MTI 200 analytical instrument gas chromatograph, which flow thereafter towards the engine intake manifold and mix with the intake air. Depending on engine load conditions, the volumetric composition of the inducted gaseous fraction is 20–50% biogas, 2–10% H₂ and 45–78% air. Near the end of the compression stroke, a small amount of diesel pilot fuel is injected to initiate the combustion of the gas–air mixture. Firstly, the engine was tested on conventional diesel mode (baseline case) and then under dual fuel mode using the biogas. Consequently, hydrogen has partially enriched the biogas. Combustion characteristics, performance parameters and pollutant emissions were investigated in-depth and compared. The results have shown that biogas enriched with 20% H₂ leads to 20% decrease of methane content in the overall exhaust emissions, associated with an improvement in engine performance. The emission levels of unburned hydrocarbon (UHC) and carbon monoxide (CO) are decreased up to 25% and 30% respectively. When the equivalence ratio is increased, a supplement decrease in UHC and CO emissions is achieved up to 28% and 30% respectively when loading the engine at 60%.     

生物制气-柴油双燃料发动机NOx计算模型

采用气化炉热解气化各种农林废弃的生物质，产生可燃生物制气，作为双燃料发动机的主要燃料。双燃料发动机由单缸、四冲程、水冷、直喷式柴油机改装，生物制气通入发动机进气管，在进气过程中吸入气缸。在油滴蒸发准维燃烧模型的基础上，结合单区模型和详细化学反应动力学机理，建立生物制气-柴油双燃料发动机的NOx生成模型，计算结果与试验结果吻合较好。供油提前角提前，生物制气-柴油双燃料发动机NOx排放量增加；引燃柴油量减小时，NOx排放量减小。     

生物制气-柴油双燃料发动机燃烧及排放分析

采用气化炉热解气化各种农林废弃的生物质,得到可燃生物制气。将柴油机改制成双燃料发动机,用生物制气作为主要燃料,由柴油引燃。测量生物制气-柴油双燃料发动机在最大扭矩转速时的气缸压力及废气排放,分析燃烧特性及对排放物生成的影响,并对比分析柴油机与双燃料发动机的差别。     

生物制气-柴油双燃料发动机放热规律试验研究

采用气化炉热解气化各种农林废弃的生物质,产生可燃生物制气,用作为以柴油引燃的双燃料发动机的主要燃料。测量生物制气-柴油双燃料发动机气缸压力,计算分析放热规律。双燃料发动机与燃用纯柴油时的发动机相比,燃烧始点延迟,最大燃烧压力降低,最大放热率和排气温度增加,后燃较严重。负荷增大时,双燃料发动机燃烧始点提前,最大燃烧放热率增高,最高燃烧温度升高,后燃较严重。供油提前角提前时,后燃减小,燃烧过程明显改善。     

Generation of combustion irreversibilities in a spark ignition engine under biogas–hydrogen mixtures fueling

Availability analysis is applied to the cylinder of a spark ignition engine during the closed part of the engine cycle when biogas–hydrogen blends, with volumetric fractions of hydrogen up to 15%, are used as fuel. The focal point is on the demonstration of the spatial distribution inside the burned gas of the combustion-generated irreversibilities for the various hydrogen concentration cases examined, which constitute one of the major sources for the defective exploitation of fuel into useful mechanical work that cannot be identified by the traditional first-law analysis. For this reason, an experimentally validated closed cycle simulation code is used, based on a multi-zone thermodynamic model of the cylinder content, applied in conjunction with a quasi-dimensional combustion model for burn rate predictions. After presenting global availability-balance-related results, pointing out the increase in the second-law efficiency of engine operation with the hydrogen enrichment of biogas, detailed information is provided regarding the spatial development of the combustion irreversibilities throughout the thermodynamically inhomogeneous burned gas, along with their link with the developed temperature field, as determined during combustion at each hydrogen fraction. It is revealed that the addition of increasing amounts of hydrogen in biogas promotes the degree of reversibility of the burning process mainly during the combustion of the later burning gas, due to the incurred increase in its combustion temperatures. On the contrary, the contribution of the early burning gas to the decrease in combustion irreversibilities with hydrogen addition seems to be less prominent.     

内燃机燃烧过程可视化实验研究浅析

介绍了研究发动机燃烧过程的模拟实验装置（定容燃烧弹和多功能燃烧弹）及单缸试验机，着重分析它们的工作原理、结构及特点。为研究内燃机的燃烧过程从而改善其燃烧特性所需的各式各样的实验装置的设计提供了有力的依据和信息参考。     

内燃机燃烧过程可视化实验研究浅析

介绍了研究发动机燃烧过程的模拟实验装置(定容燃烧弹和多功能燃烧弹)及单缸试验机,着重分析它们的工作原理、结构及特点。为研究内燃机的燃烧过程从而改善其燃烧特性所需的各式各样的实验装置的设计提供了有力的依据和信息参考。