借助纯氧实现柴油机NOx零排放与增压

内燃机废气排放是目前环境污染的主要来源;而处理内燃机废气排放,降低NOx排放的难度最大。可是内燃机燃料中并不含有氮元素,NOx排放主要来源于空气中的氮气在高温高压下与氧气反应。通过研究发现,利用纯氧代替空气实现内燃机的燃烧,可以实现NOx零排放;同时把燃烧后的废气再循环(exhaust gas recycle,简称EGR)引入气缸,以降低燃烧的剧烈程度,并通过控制EGR量可增压内燃机,进而可以取消增压器。     

国家科技成果重点推广项目

JNQ 型内燃机电子节能器该装置应用电子、物理和化学综合技术,产生一种比空气氧化能力更强、遇热极易分解成氧并释放热量的气体——臭氧 O_3去促进燃油的充分燃烧,从而实现节油、降低有害气体排放量和提高发动机功率等功能。该装置由电源变换器和空气分离器组成。电源变换器的作用是把内燃机上的低压直流电变     

国家科技成果重点推广项目

JNQ型内燃机电子节能器 该装置应用电子、物理和化学综合技术,产生一种比空气氧化能力更强、遇热极易分解成氧并释放热量的气体——臭氧O_2去促进燃油的充分燃烧,从而实现节油、降低有害气体排放量和提高发动机功率等功能。该装置由电源变换器和空气分离器组成。电源变换器的作用是把内燃机上的低压直流电变换成高频高压电,作用于空气分离器的正、负电极,由此产生电晕效应。空气分离器的作用是在电晕效应作用下产生助燃性极强的臭氧O_3,通过进气口送入汽缸,促进燃油充分燃烧。     

内燃机燃烧研究及面临的挑战

内燃机在运行的过程中,会经历一个化学反应和能量的转换,在这一过程中会涉及到很多的学科知识。内燃机的燃烧过程还没有被技术人员研究透彻。在实际的燃烧过程中有可能会出现碳粒。内燃机需要严格的控制排放的过程,这样可以降低油耗指标。此外,内燃机在燃烧方面的技术也在进一步的研发中。本文主要阐述了内燃机燃烧研究以及会面对的挑战。     

内燃机燃烧模拟现状及应用的研究

传统的内燃机燃烧过程的探索主要通过燃烧实验,但受实验条件、检测条件等多方面限制,燃烧过程很难被控制,研究针对内燃机燃烧模拟方向进行现状分析及应用探讨,减少了燃烧实验难度,内燃机的燃烧决定了内燃机的动力效果与经济价值,对内燃机的排放与环境影响程度也有着重要影响作用。     

内燃机燃烧研究及面临的挑战

内燃机的燃烧是一个化学反应和能量转换的过程,它涉及到许多学科,内燃机的燃烧过程还没有被人研究透彻,比如燃烧过程中碳粒的生成。严格的排放法规和油耗指标将会推动内燃机的进一步发展,另外,一些新的概念也会推进内燃机燃烧方面的研究。燃烧的优化和燃烧后的处理技术是实现低污染和零排放的重要途径。本文分析了内燃机燃烧研究和今后面临的各种挑战。     

内燃机燃烧理论新进展

传统内燃机在能量利用率和有害产物控制两个方面已达到极限。本文介绍新一代内燃机燃烧理论及其3种燃烧模式，其核心思想是发展“内燃机均质、压燃、低温火焰燃烧和燃烧边界条件与燃烧化学协同控制理论”，可同时实现节能和减少有害物质排放的目标。     

内燃机零部件结构设计及应用设想分析

不同时期工业行业发展对动力需求具有明显差异。在现阶段全球经济一体化发展的基础上,要充分发挥内燃机的应用优势,在保证其运行效率的同时降低有害气体的排放,从而促进新时期环境友好化发展。本文阐述了内燃机发展过程,并对内燃机结构组成、内燃机零部件结构设计的必要性和重要性进行分析,并从内燃机零部件结构设计、内燃机运行流程设计两个方面展开讨论,最后针对内燃机零部件结构设计做出展望,旨在促进内燃机零部件结构设计的科学和创新。     

小型内燃机电子燃油喷射和闭环控制系统研究

针对当前小型内燃机存在的动力和排放上的缺陷,借鉴了广泛应用的电控燃油喷射技术和PID控制技术,构建了一套新型电子燃油喷射和闭环控制系统,用于当前内燃机的排放降低和动力提升环节。通过实验证明了本系统能够有效实现可燃混合气空燃比控制,并显著降低排放,提升动力性能,具有较好的应用潜力。     

数学建模研究内燃机排放性能及控制问题

出于对以往研究手段不足的考虑,结合BP神经网络优势,针对内燃机稳态排放建立BP神经网络数学分析模型,对排放性能展开研究,发现负荷较大时,内燃机NOX与碳烟排放水平比较高。进一步地,为了降低对大气的污染,提出相应内燃机排放控制建议,本文研究可以为相关人员采取有效措施控制内燃机排放污染提供一定借鉴与参考。     

The effect of combustion parameters on the nitric oxide emission in direct injection type diesel engine

This paper presents the investigation of influence factors on the output performance and the reduction of exhaust emission in the direct injection type diesel engine. In this work, the analysis of combustion products and combustion characteristics are investigated by numerical method and experiment under the various engine operating conditions. The combusion performance and exhaust emissions are analyzed in terms of the heat release, cylinder pressure and major exhaust emissions of engine. The accuracy of the prediction versus experimental data and the capability of the heat release, cylinder pressure and all the major exhaust emissions are demonstrated. The results of this study show that the combustion parameters have influence on the combustion processes and the nitric oxide emission in the direct injection type diesel engine. The nitric oxide concentration decreases with the increase of engine speed and the advance of injection timing.     

A study on characteristics and control strategies of cold start operation for improvement of harmful exhaust emissions in SI engines

Emission regulations for automobiles have become more stringent and the improvement of emission during cold start has been a major key issue to meet these regulations. Among many kinds of factors that affect cold start operation, ignition timing is crucial to improve emission characteristics due to the influence on exhaust gas temperature. Recent progress in variable valve timing allows optimized valve event strategies under various ranges of engine operating conditions including cold start. This study investigates effects of ignition and exhaust valve timing on exhaust gas temperature, combustion stability and emission characteristics through cold start bench tests of an SI engine. Experimental results show that exhaust valve timings and ignition timings significantly affect exhaust gas temperature and stability of engine operation under cold start condition. Exhaust valve timing also affects CO and NO_x emission due to changes in residual gas fraction of the combustion chamber. Ignition timing mainly affects exhaust gas temperature and HC emission. A control strategy, advanced exhaust valve timing and retarded ignition, is plausible in order to achieve reduction of exhaust emission while maintaining stability under cold start operation of SI engines.     

基于 EGR 耦合米勒循环的柴油机排放控制技术

为了提升柴油机应用过程有害废气排放控制的效果,提出基于 EGR 耦合米勒循环的柴油机排放控制技术。以燃油燃烧各阶段为基础,构建柴油机燃烧模型,分别深入分析 EGR 技术与米勒循环技术对废气排放的影响,衡量指标为 EGR 率与米勒度。以废气排放影响分析结果为依据,以排放控制效果最佳为目标,确定 EGR 技术与米勒循环技术的最佳耦合方案,实现柴油机废气排放的最佳控制。实验数据表明,应用 EGR 耦合米勒循环技术后,废气排放量低于实际废气排放量,并低于 EGR 技术与米勒循环技术对应排放量,充分证实了该技术具备较好的排放控制效果,为大气环境保护提供帮助。     

The measurement method solving the problems of engine output characteristics caused by change in atmospheric conditions on the principle of the theory of optimal temperature range of exhaust system

All high-performance engines are sensitive to changes in external atmospheric conditions, which are immediately reflected in changes in the engine output characteristics. At best only they effect decreasing of the maximum engine power. However, in a more difficult situation, there is the possibility of excessive detonation combustion process during certain changes in atmospheric conditions. The exhaust system temperature significantly affects the maximum output power and the combustion engine characteristics. With increasing temperature of combustion products in the exhaust system there is an overall reduction in maximum power and its transfer to a higher engine speed because of the length of an exhaust manifold is theoretically shorten. Therefore, to achieve the maximum values of output parameters, it is necessary to ensure an optimal temperature value of the combustion products in the exhaust system. This article also provides optimal temperature range of working temperature as well as it presents a theoretical analysis of the impact for atmospheric conditions in this interval. Based on theoretical results there has been developed a measuring method, which allows to regulate the input amount of the fuel mixture supplied to a cylinder during change in atmospheric conditions and its functionality was experimentally verified.     

LJ465Q-2AE1汽油机满足欧Ⅲ排放标准的研究

LJ465Q-2AE1发动机是新研制开发达到欧Ⅲ排放要求的汽油机,它具有结构紧凑、升功率大、油耗低、转速高、噪声小等特点。笔者介绍了如何对该汽油机的燃烧系统、进气系统、点火系统及排气催化转化系统进行的优化设计。     

The effect of exhaust gas recirculation (EGR) on combustion stability, engine performance and exhaust emissions in a gasoline engine

The EGR system has been widely used to reduce nitrogen oxides (NOx) emission, to improve fuel economy and suppress knock by using the characteristics of charge dilution. However, as the EGR rate at a given engine operating condition increases, the combustion instability increases. The combustion instability increases cyclic variations resulting in the deterioration of engine performance and emissions. Therefore, the optimum EGR rate should be carefully determined in order to obtain the better engine performance and emissions. An experimental study has been performed to investigate the effects of EGR on combustion stability, engine performance, NOx and the other exhaust emissions from 1. 5 liter gasoline engine. Operating conditions are selected from the test result of the high speed and high acceleration region of SFTP mode which generates more NOx and needs higher engine speed compared to FTP-75 (Federal Test Procedure) mode. Engine power, fuel consumption and exhaust emissions are measured with various EGR rate. Combustion stability is analyzed by examining the variation of indicated mean effective pressure (COV_imep) and the timings of maximum pressure (P_max) location using pressure sensor. Engine performance is analyzed by investigating engine power and maximum cylinder pressure and brake specific fuel consumption (BSFC).     

基于尾气排放分析发动机故障

发动机各系统是否正常工作直接影响着燃烧质量,而发动机尾气可反映混合气的燃烧质量。通过分析尾气中的HC、CO、NOx等成分的比例,可以为快速分析发动机故障提供便捷的途径,并由实车故障案例分析证明通过尾气检测来分析发动机故障是切实可行的。     

Optical investigation of the fuel injector influence in a PFI spark ignition engine for two-wheel vehicles

This paper describes the results obtained in a port fuel injection spark-ignition (PFI SI) engine by optical diagnostics during the fuel injection and the combustion process. A research optical engine was equipped with the fuel injection system, the head and the exhaust device of a commercial 250 cc engine for scooters and small motorcycles. Two injectors were tested: standard 3-hole injector that equipped the real reference engine and a 12-hole injector. The intake manifold was modified to allow the visualization of the fuel injection using an endoscopic system coupled with CCD camera. Size and number of the fuel droplets were evaluated through an image processing procedure. The cycle resolved visualization and chemiluminescence allowed to follow the combustion process from the spark ignition to the exhaust phase. All the optical data were correlated with engine parameters and exhaust emissions. The effect of the fuel injector type on deposits formed by fuel accumulation and dripping on the intake valves steams and seats was investigated. In particular, the evolution of diffusion-controlled flames due to the fuel deposits burning was analyzed. These flames were principally located near the intake valves, and they persisted well after the normal combustion event. The consequences were the formation and emission of soot and unburned hydrocarbons. The multi-hole injector helped reducing wall wetting and deposit formation so that the emission characteristic can be improved. The use of 12-hole injector allowed a more homogeneous distribution for a lower time of fuel droplets in the intake manifold than the 3-hole injector. This study also investigated the detailed physical/chemical phenomena to figure out reasons for the improvement using optical measurements.     

Performance and emission characteristics of a low heat rejection spark ignited engine fuelled with E20

In internal combustion engines, the concept of low heat rejection (LHR) using thermal barrier coating on the surface of combustion chamber is gaining attention. Thermal barrier coating reduces the heat transfer to the cooling system, protects engine components from peak heat flux and fluctuating temperature produced during combustion and improves the performance of the engine. Information in the literature is plentiful for LHR diesel engine and only few studies exist on LHR spark ignited engine. The application of thermal barrier coating in spark ignited engine is limited by pre-ignition and knocking due to elevated combustion chamber temperature. A spark ignited engine with moderate insulation on the combustion chamber and higher octane fuel can overcome this difficulty. The objective of the present experimental study is to quantify the changes in performance and emission characteristics brought by partial thermal insulation on the combustion chamber of a four stroke spark ignited engine fueled with E20 blend. Partial thermal insulation was created by coating 0.3 mm thick Alumina (Al₂O₃) on the cylinder head, inlet and exhaust valves. The changes are quantified with respect to unmodified engine fueled with gasoline. The combustion parameters such as flame development and rapid burn duration are also estimated and compared. The results indicate that partially insulated SI engine when fueled with E20 improves performance and reduces emission. A maximum of 48% reduction in THC and 50% reduction in CO emission at part load was achieved.

     

Non-thermal plasma for exhaust gases treatment

This article describes a study on a non-thermal plasma device to treat exhaust gases in an internal combustion engine. Several tests using a plasma device to treat exhaust gases are conducted on a Honda GX200-196 cm³ engine at different rotational speeds. A plasma reactor could be efficient in degrading nitrogen oxides and particulate matter. Monoxide and carbon dioxide treatment is minimal. However, achieving 1%–3% degradation may be interesting to reduce the emission of greenhouse gases.