柴油/CNG双燃料发动机排放性能的试验研究

在设计开发的CA6113BN-01柴油/CNG双燃料发动机的基础上，通过改变燃烧系统参数，柴油供油系统参数和在天然气供气系统参数等，研究了这些参数变化时对柴油/CNG双燃料发动机排放特性的影响。试验结果表明：柴油/CNG双燃料发动机的燃烧室形状对双燃料发动机性能，排放的影响较小。NOx、HC排放量随提前角的变化趋势和柴油机相似，提前角增大，NOx排放量增加，HC排放量也增加，提前角对CO排放影响较小。喷油器的开启压力提高可以有效地改善双燃料发动机的排放。     

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。     

低热值燃气-柴油双燃料发动机动力性能计算

推导了低热值燃气-柴油双燃料发动机动力性能计算公式,并对由单缸、四冲程、水冷、直喷式柴油机改装的生物制气-柴油双燃料发动机的动力性能进行了计算分析。结果表明：双燃料发动机能够达到原柴油机的动力水平;其动力性能随引燃油量的减小而降低;在新鲜空气充足的前提下,供给更多的燃气,双燃料发动机的动力性能增强;燃气替代率有一最大值,超过该值后,随替代率增大,动力性能急剧下降;燃气低热值越高,替代率便可越大。计算得出的生物制气-柴油双燃料发动机在标定点和最大转矩点的最大生物制气替代率和对应的燃气进气比,与试验结果相吻合。     

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。     

燃烧系统参数对增压中冷柴油-天然气双燃料发动机排放特性和经济性影响的实验研究

将一台6缸、增压中冷柴油机改装为混合器进气方式的柴油—天然气双燃料发动机，对其燃烧系统参数对双燃料发动机排放和经济性的影响进行了实验研究，包括引燃柴油喷油时刻、天然气替代率、中冷后进气温度的影响。双燃料发动机的排放与空燃比及燃烧系统参数密切相关。替代率增加时，排气烟度降低，HC排放升高，当量燃油消耗率升高，CO排放在替代率较小时随替代率增加而升高，但在替代率较高时随替代率增加而略有降低。替代率对NOx排放的影响则与发动机工况有关，在最大转矩和低速大负荷工况，空燃比值较小，NOx排放随替代率的升高而增大；在标定功率工况，空燃比较大，NOx排放随替代率的升高而减小。提前角减小，NOx排放降低。中冷后温度升高，碳烟排放和NOx排放升高，HC和CO排放降低，当量燃油消耗率降低。研究结果表明，采用增压中冷技术、提高CNG替代率、减小引燃柴油喷油提前角，能够有效地降低双燃料发动机的有害排放物。     

LPG／柴油双燃料发动机的试验研究

LPG／柴油双燃料发动机以其高效率，低污染成为最有前景的发动机之一，本文以485柴油机为样机，在LPG／柴油双燃料方式下对发动机的动力特性以及排放特性进行了台架试验研究，试验结果表明，LPG／柴油双燃料发动机可以在保持原机高功能的前提下，降低原机的排放量，尤其是烟度和NOx的排放。     

燃烧乙醇-柴油时发动机的性能与排放特性研究

在一台双缸直喷式柴油机上,对燃烧乙醇-柴油时发动机的燃油经济性和排放性进行试验。试验结果表明：与纯柴油相比,乙醇-柴油的当量燃油消耗率和CO排放量在较大负荷工况下有所减小,NOx和碳烟排放在各种工况下都显著降低,但HC的排放量增加;适当减小发动机的供油提前角,对提高燃油经济性和排放性有利。     

LPG/柴油双燃料发动机的试验研究

LPG/柴油双燃料发动机以其高效率,低污染成为最有前景的发动机之一.本文以485柴油机为样机,在LPG/柴油双燃料方式下对发动机的动力特性以及排放特性进行了台架试验研究.试验结果表明,LPG/柴油双燃料发动机可以在保持原机高功率的前提下,降低原机的排放量,尤其是烟度和NOx的排放.     

氢气/柴油双燃料发动机排放特性研究

新能源和环保是当今内燃机研究的热点.通过对ZS1100型柴油机加装氢气进气系统,实现了氢气/柴油双燃料的燃烧.排放特性研究表明:氢气/柴油双燃料发动机可以大幅度减少碳烟排放量,但NOx排放量在中小负荷时减少,而大负荷时增加.     

生物柴油发动机NOx排放影响因素的数值模拟

根据生物柴油与柴油物性参数的差别,对柴油缸内喷雾燃烧模型进行修正,建立了生物柴油的缸内喷雾燃烧模型,利用该模型计算得到的缸内压力示功图与试验结果进行对比,验证了模型的准确性;利用AVL - fire软件,计算了发动机参数对生物柴油NOx排放的影响规律,着重考察了喷孔直径、喷雾锥角、喷油提前角、EGR率对燃烧温度和NOx...     

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’.     

甲醇/柴油双燃料发动机的性能

在一台柴油机基础上，采用气道口电控喷射甲醇，缸内柴油引燃甲醇的方式，开发了电控甲醇／柴油双燃料样机，并通过发动机台架实验，研究了柴油／甲醇双燃料燃烧模式在燃烧特性、燃油经济性及排放性能方面的特点．与原发动机相比，双燃料模式的最高爆发压力下降，压力升高率上升，排烟和NOx大幅度下降，但THC和CO排放均升高．该方法能使甲醇喷射量得到精确控制以便燃烧达到最佳状态，是甲醇／柴油双燃料发动机可行的技术方案．     

Application of machine learning and Box-Behnken design in optimizing engine characteristics operated with a dual-fuel mode of algal biodiesel and waste-derived biogas

Waste-derived biogas and third-generation algal biodiesel are attractive alternative fuels to substitute fossil diesel in a diesel engine. However, using biodiesel as a pilot liquid fuel and biogas as the main fuel in a diesel engine is a complicated and highly non-linear process. The current study seeks to predict and optimize the combustion and exhaust emission characteristics of a variable compression dual-fuel combustion engine. Data from experiments were obtained at a variety of engine loads, compression ratios, pilot fuel injection pressures, and timings. A multi-layer perceptron network was employed to develop an Artificial Neural Network (ANN) based prognostic model using the experimental data. The developed prognostic model was used to estimate brake thermal efficiency, biogas flow rates, peak in-cylinder pressure, carbon dioxide, unburned hydrocarbons, oxides of nitrogen, and carbon monoxide. The predictive model's robustness is demonstrated by statistical metrics such as R (0.9723–0.988) and R² (0.9453–0.9761), Nash-Sutcliffe model efficiency (94–97%), and mean absolute percentage error (0.013–0.128%), Kling-Gupta efficiency (0.9548–0.9836), and Theil's U2 model uncertainty (0.162–0.368). To optimize the parameters of dual-fuel combustion, the Multi-Output Response Surface Methodology (RSM) was employed. The trade-off assessment between emission and efficiency using the desirability approach revealed that 84% engine load, 244 bar of fuel injection pressure, 28 °BTDC of injection timing, and 17.5 compression ratio are the best-operating conditions for the test engine. An experimental investigation was used to corroborate the RSM research findings, and errors were less than 9%. It was revealed that ANN-linked RSM is a good hybrid technique for modeling, prediction, and optimization of the performance of a dual-fuel engine.     

Modeling-optimization of performance and emission characteristics of dual-fuel engine powered with pilot diesel and agricultural-food waste-derived biogas

Gaseous-liquid fuel combinations of biogas as primary fuel and diesel as pilot fuel were employed to power a compression ignition (CI) engine in this study. The effects of variable input factors such as engine load, compression ratio, and pilot fuel injection advance on the dual-fuel engine's combustion, thermal, and emission performance were investigated. The data acquired during this lab-based testing was used to develop a prognostic model using a Bayesian optimization strategy for hyperparameter optimization and a contemporary ensemble Gaussian process regression (GPR) technique. During model testing, the error analysis revealed that the developed model could predict the experimental data rather correctly, with R² values ranging from 0.9995 to 0.9999 and MSE values ranging from 0.00018 to 0.1334. The mean absolute error was discovered to be between 0.0091 and 0.3065. Consequently, the developed GPR model can effectively simulate the on-board performance, emission, and combustion characteristics of a diesel-biogas dual-fuel setting. As a consequence, the current work established the GPR model in the existing CI engine meta-modeling framework as a consistent, trustworthy, and robust system analytical approach for diesel-biogas dual fuel mode of operation.     

Combined impact of varying biogas mass flow rate and rice bran methyl esters blended with diesel on a dual-fuel engine

ABSTRACT

For fetching day-to-day energy needs, current energy requirement majorly depends on fossil fuels. But ambiguous matter like abating petroleum products and expanding air pollution has enforced the experts to strive for another fuel which can be used as an alternative or reduce the applications of fossil fuels. Considering the issues, the main objective of the present study is to find the feasibility by using blends of rice bran oil biodiesel and diesel which are used as pilot fuels by blending 10% and 20% biodiesel in fossil diesel and biogas, introduced as gaseous fuel by varying its mass flow rate in a dual-fuel engine mode. An experimentation study was carried out to find the performance and emission parameters of the engine relative to pure diesel. The results were very much similar to the majority of researchers who used biodiesel and gaseous fuels in a dual-fuel engine. Brake specific fuel consumption (BSFC) of the engine was noticed to have increased, while brake thermal efficiency was on the lower side in dual fuel mode in comparison with regular diesel. In relation with conventional diesel, it was noticed that combined effect of rice bran methyl esters and varying mass flow rate of biogas showed a decrement in NO _x and smoke emissions, whereas HC and CO exhalations were on higher side when biogas and biodiesel were utilized collectively in dual-fuel engine. Hence, it was concluded that combination of blends of biodiesel and diesel and introduction of biogas in the engine can be a promising combination which can be used as a substitute fuel for addressing future energy needs.     

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%.     

非直喷式柴油机气态污染物形成历程研究

本文应用新研制的全气缸取样系统测量了一台S195型涡流室式柴油机气缸内NO_x、CO浓度随曲轴转角的变化历程。考查了负荷、转速和喷油提前角对NO_x、CO浓度变化历程的影响。实验结果同计算机模拟结果作了对比,两者基本吻合。