等离子燃烧器无油冷态点火技术的探讨

结合大唐托克托电厂四期工程7号炉成功实现等离子无油冷态点火的实践,针对该项工程中等离子燃烧器的改造及点火和稳燃过程中的调整措施进行分析,总结经验。     

金属基电热膜引燃能力研究

为研究金属基电热膜的引燃能力,以棉被、毛巾为覆盖物,对不同电热膜通电功率、不同覆盖物厚度和含水率条件下,覆盖物不同位置处的温度变化情况进行了实验研究,并通过建立相应的模型,计算得到了不同环境温度下,覆盖物与电热膜接触处的温度.研究结果可以为电热膜火灾的预防,以及电热膜火灾的原因调查提供一定的参考.     

EVA/MWNTs复合材料的阻燃性能

综述了近几年来乙烯-乙酸乙烯酯共聚物/多壁碳纳米管（EVA/MWNTs）纳米复合材料的研究进展,介绍了其制备方法,详述了其热解行为及阻燃性能（包括热释放速率、引燃时间、成炭性）,并对其阻燃机理进行了深入的讨论。比较了MWNTs、有机黏土、层状双氢氧化物等不同纳米填料的阻燃性能,分析了对MWNTs进行不同处理（包括纯化、使用高密度聚乙烯进行表面涂覆改性、研磨）对相应纳米复合材料的热稳定性及可燃性的影响。     

CO火焰对碳粒燃烧影响的理论分析和实验研究

建立了球坐标系下传热、传质和化学反应全耦合的碳粒燃烧数值模拟程序．在详细理论计算的配合下，通过精密设计的实验研究，用FTIR透射-发射实验测温方法成功捕捉了持续时间极短的“CO在颗粒表面被点燃而引起的颗粒高温”现象．连续膜模型的计算结果和FTIR测温实验结果表明，CO的空间反应与碳粒表面反应的相互作用及其对碳粒表面温度、总体反应速率的影响是极其复杂的．而CO能否在颗粒表面附近被点燃及其所引起的颗粒表面温度差可高达数百度．在实际煤粉火焰条件下，单膜模型和严格的连续膜模型的预报结果相差比较大，特别是对着火点及着火后某段区间内的颗粒温度的预报，是仅考虑表面氧化反应C＋1／2 O2→CO的单膜模型所无法完成的，这说明单膜模型存在较大的应用局限性．     

初始进气充量成分对末端气体自燃化学特性的影响

本文介绍了在一台单缸二冲程爆震实验发动机上，研究进气充量中不同的残余气体成分对焰前反应及自燃的影响的实验结果。结果表明，初始进气充量中含有一定量的残余废气时，抑制了自燃；在残余废气中含有一定量的部分氧化产物时，促进了低温化学反应和自燃。低温化学反应所释放的热量以及活性中间产物的积累导致了终燃混合气的自燃。ＲＯＮ５３汽油的自燃过程表现为两阶段着火特征。     

煤气爆炸极限和安全动火浓度的确定

本文主要通过煤气组分比值的变化,确定其爆炸极限和安全动火浓度值。     

一种可控火花能量的交流点火系统研究

基于电容储能式电控点火系统研究了一种火花持续期、次级火花电流可控的交流点火系统。利用CADENCE PSPICE软件以及模拟负载试验,验证了不同斩波电流、驱动脉宽等可变参数对交流点火系统火花能量的影响。试验结果表明:火花能量的提高依赖于斩波电流值的增大和驱动脉宽的延长,并近似呈线性关系;交流点火系统火花持续时间可实现2.5 ms内可控调节,初级斩波电流可实现30 A内可控调节。交流点火系统可通过相应参数的调节实现火花能量可控,最大火花能量可达到260 mJ,满足气体燃料发动机的功能需求。     

Ignition kinetics of a homogeneous hydrogen/air mixture using a transient hot jet

The ignition characteristics of a homogenous hydrogen/air mixture using a hot transient jet generated by the combustion of syngas (H₂/CO) with varying CO concentrations from 33% to 95% in a pre-chamber is numerically investigated with particular attention to the chemical kinetics. Detailed reaction mechanism for hydrogen and syngas mixture oxidation with 15 species and 41 reactions is employed. The hot jet ignition delay time is determined by the onset of OH¹ radicals and found to increase with increasing CO molar fractions in the pre-chamber fuel, and this increase is more profound for high CO content. The radicals that formed in the main chamber are examined separately from the radicals within the hot jet. Their temporal evolutions reveal that O and OH radicals in the jet play a crucial role in abstraction of H atoms form ${\text{H}}_2$/air mixture in the main chamber, which initiates ignition. Further analysis of the ${\text{H}}_2{\text{O}}_2$ rate of change identifies two ignition regimes. For high temperature (T > 1000 K) hot jets, ignition is caused by the chain branching reaction $\text{H}+{\text{O}}_2?\text{O}+\text{OH}$ directly, resulting in short ignition delay times (0.14, 0.19, 0.26 ms). For low temperature (T < 1000 K) hot jets, ignition is dominated by the accumulation and decomposition of ${\text{H}}_2{\text{O}}_2$, resulting in long ignition delay times (0.4, 0.67, 1.26 ms). By separating the thermal and chemical effects of the hot jet, it is found that the thermal effects are dominant but composition of the hot jet has little effect on the ignition characteristics.     

LPG单燃料发动机电控标定的研究

简要介绍了电控单燃料LPG发动机电控系统的组成情况 ,对不同工况下的空燃比、点火提前角及废气旁通阀的开度等进行了实验标定 ,并通过发动机台架试验 ,考察了LPG发动机的总体性能。所采用的控制方法对开发LPG单燃料电控发动机具有一定的指导意义     

Spectroscopic and chemical-kinetic analysis of the phases of HCCI autoignition and combustion for single- and two-stage ignition fuels

The temporal phases of autoignition and combustion in an HCCI engine have been investigated in both an all-metal engine and a matching optical engine. Gasoline, a primary reference fuel mixture (PRF80), and several representative real-fuel constituents were examined. Only PRF80, which is a two-stage ignition fuel, exhibited a “cool-flame” low-temperature heat-release (LTHR) phase. For all fuels, slow exothermic reactions occurring at intermediate temperatures raised the charge temperature to the hot-ignition point. In addition to the amount of LTHR, differences in this intermediate-temperature heat-release (ITHR) phase affect the fuel ignition quality. Chemiluminescence images of iso-octane show a weak and uniform light emission during this phase. This is followed by the main high-temperature heat-release (HTHR) phase. Finally, a “burnout” phase was observed, with very weak uniform emission and near-zero heat-release rate (HRR). To better understand these combustion phases, chemiluminescence spectroscopy and chemical-kinetic analysis were applied for the single-stage ignition fuel, iso-octane, and the two-stage fuel, PRF80. For both fuels, the spectrum obtained during the ITHR phase was dominated by formaldehyde chemiluminescence. This was similar to the LTHR spectrum of PRF80, but the emission intensity and the temperature were much higher, indicating differences between the ITHR and LTHR phases. Chemical-kinetic modeling clarified the differences and similarities between the LTHR and ITHR phases and the cause of the enhanced ITHR with PRF80. The HTHR spectra for both fuels were dominated by a broad CO continuum with some contribution from bands of HCO, CH, and OH. The modeling showed that the CO+O→CO₂+hν reaction responsible for the CO continuum emission tracks the HTHR well, explaining the strong correlation observed experimentally between the total chemiluminescence and HRR during the HTHR phase. It also showed that the CO continuum does not contribute to the ITHR and LTHR chemiluminescence. Bands of H₂O and O₂ in the red and IR regions were also detected during the HTHR, which the data indicated were most likely due to thermal excitation. The very weak light emission in the “burnout” phase also appeared to be thermal emission from H₂O and O₂.