使用可调式炉具进风口的必要性

炉具的设计首先要考虑的问题是燃气具的热效率,而影响燃气具热效率的很大一个方面是炉具进风口的大小,通过分析灶的热交换过程,确定了燃烧热效率与炉具锅支架高度及一次空气系数的关系;确定热效率的函数关系表达式;确定了约束条件的数学表达式,并阐明在炉具的设计中使用可调式炉具进风口是非常必要的。     

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。     

高能点火放电方式对全烧式沼气发动机性能的影响

在全烧式沼气发动机上，对采用两种不同放电方式的高能点火系统进行了实验研究，结果表明：通过延长放电持续期所实现的高能点火，对改善全烧式沼气发动机必的作用不大，而增大放电初期的放电电压和电流可明显是全烧式沼气发动机的性能。     

对摩托车点火系统电子控制的研究

本文介绍了在摩托车发动机点火系统中采用Ｍｏｔｏｒｏｉａ单片机调节点火延迟角，对点火时间进行控制的方法。实验结果表明，该系统使发动机的点火时间得到了有效的控制。     

GD—110型无触点电子点火系统的研制

一、前言 车辆废气排放是环境污染的重要来源之一,随着汽车、摩托车产量和社会保有量的增加,大气污染日趋严重。降低车辆排放可从三个方面入手:（1）改善化油器,采用稀薄燃烧技术;（2）精确控制发矿机点火时间,提高点火能量;（3）装用三元催化剂。几十年来,我国车辆废气排放和油耗的降低,主要靠用机械加工技术完成,例如改善化油器及采用曲轴箱强制通风技术等。到目前为止,受机械加工精度的制约,进一步改进的难度很大。装用三元催化剂必须使用无铅汽油,这在我国目前是不可能的,况且催化剂中贵金属（特别是铑Rh）的价格很高。另外采用稀薄燃烧的基础是必须选用高能电子点火。 我国自第一辆机动车制造以来,发动机点火系统长期没有变化,一直选用蓄电池点火,主要是因为价格低、维修方便。但白金触点易磨损,点火能量不高,导致油耗增加和排     

以紧凑式微机为基础的全电子点火系统

介绍了以紧凑式微机为基础的无分电器全电子点火系统。该系统可完全取代机械分电器点火系统，并以最少的硬件实现更可靠，精确，复杂的点火正时。文中讨论了该系统的工作原理，并报道了发动机台架稳态工况试验的结果。     

电控汽油喷射发动机中点火线圈与喷油器的控制

详细分析了电控汽油喷射发动机中点火线圈控制信号与喷油器控制信号的定时关系，提出采用双可编程定时／计数器联动产生控制信号的方法，并对这种方法的控制精度及其优缺点给予分析与评价。     

基于Ne555的耐压测试器在汽车电子点火系统故障中的应用

利用Ne555自制了一个晶体管耐压测试器,该测试器可以在检修汽车电子控制点火装置过程中对点火装置的部件进行测试,并对分段进行诊断的经验加以总结。重点探讨点火装置疑难故障的诊断分析方法,并给出了一个诊断实例。     

全玻璃真空集热管太阳热水器的常见故障

经多年发展，全玻璃真空管太阳热水器日趋成熟已形成相当的产业规模，但与燃气热水器、电热水器相比，使用中暴露出的可靠性差、故障率高、维修量大等一系列问题加大了经营成本，成为经销商的沉重负担。有些经销商已退出这一市场，还有些经销商由经营成本高的名牌产品转向经营成本低的非名牌产品。已经营5年的江苏某名牌厂家广东省总代理，因维修量过大，造成亏损而打算另换门庭。可见提高产品质量、降低故障率、减少售后维修服务成本，仍然是生产厂家需要大力解决的问题。除此之外，全玻璃真空管太阳热水器本身还因结构缺陷而造成一些问题和使用的不便。这一切都降低了太阳热水器的竞争力。     

HX_N5型机车运用中的一些惯性故障分析与处理

对HXN5型机车运用中发生的控制系统通讯中断、牵引电动机通风机控制器TBC停止工作、机车撒砂系统不能完全手动控制、空气压缩机不打风或打风慢等一些惯性质量问题进行分析,并提出了相应的解决措施。     

Large eddy simulation of spark ignition in a turbulent methane jet

Large eddy simulation (LES) is used to compute the spark ignition in a turbulent methane jet flowing into air. Full ignition sequences are calculated for a series of ignition locations using a one-step chemical scheme for methane combustion coupled with the thickened flame model. The spark ignition is modeled in the LES as an energy deposition term added to the energy equation. Flame kernel formation, the progress and topology of the flame propagating upstream, and stabilization as a tubular edge flame are analyzed in detail and compared to experimental data for a range of ignition parameters. In addition to ignition simulations, statistical analysis of nonreacting LES solutions is carried out to discuss the ignition probability map established experimentally.     

The ignition characteristics of the pre-chamber turbulent jet ignition of the hydrogen and methane based on different orifices

In this paper, the combustion characteristics of premixed CH₄-air and H₂-air mixtures with different excess air coefficients ignited by hot jet or jet flame are investigated experimentally in a constant volume combustion chamber (CVCC). The small volume pre-chambers with different orifices (2 or 3 mm in diameter) in the passive or active pre-chamber were selected. Both the high-speed Schlieren and OH1 chemiluminescence imaging are applied to visualize the turbulent jet ignition (TJI) process in the main chamber. Results show that the variation of orifice has diverse influences on the turbulent jet ignitions of methane and hydrogen. Smaller orifices will reduce the temperature of the jet due to the stronger stretch and throttling effect, including change of lean flammability limit, ignition delay, and re-ignition location. Furthermore, shock waves and pressure oscillations were captured in the experiments with hydrogen jets. The former is related to the jet velocity, while the latter is mainly affected by the mixture thermodynamic states in the main chamber. Furthermore, the re-ignition location is discussed. If the mixture reactivity and the jet energy are sufficiently high, the reaction will be initiated at the tip of the jet in a short time. On the contrary, a relatively long time is required to prepare the mixture during the entrainment when the reactivity is not high enough, and the corresponding re-ignition location will move towards the orifice exit owing to the temperature decline at the tip. Finally, the ignition mode transition of hydrogen jet in lean cases with a 2 mm orifice is explained.     

Flame propagation and counterflow nonpremixed ignition of mixtures of methane and ethylene

The ignition temperature of nitrogen-diluted mixtures of methane and ethylene counterflowing against heated air was measured up to five atmospheres. In addition, the stretch-corrected laminar flame speeds of mixtures of air, methane and ethylene were determined from outwardly-propagating spherical flames up to 10 atmospheres, for extensive range of the lean-to-rich equivalence ratio. These experimental data, relevant to low- to moderately-high-temperature ignition chemistry and high-temperature flame chemistry, respectively, were subsequently compared with calculations using two detailed kinetic mechanisms. A chemical explosive mode analysis (CEMA) was then conducted to identify the dominant ignition chemistry and the role of ethylene addition in facilitating nonpremixed ignition. Furthermore, the hierarchical structure of the associated oxidation kinetics was examined by comparing the sizes and constituents of the skeletal mechanisms of the pure fuels and their mixtures, derived using the method of directed relation graph (DRG). The skeletal mechanism was further reduced by time-scale analysis, leading to a 24-species reduced mechanism from the detailed mechanism of USC Mech II, validated within the parameter space of the conducted experiments.     

Hydrogen as an additive to methane for spark ignition engine applications

The performance of a gas fuelled spark ignition engine is enhanced when relatively small amounts of hydrogen are present with methane. This improvement in performance, which is especially pronounced at operational equivalence ratios that are much leaner than the stoichiometric value, can be attributed largely to the faster and cleaner burning characteristics of hydrogen in comparison to methane. Through analytical simulation of engine performance, the addition of hydrogen is considered through its production in situ on board the engine by electrolysis of water with the necessary energy supplied from engine power. It is shown that when the work energy required for the production of hydrogen by electrolysis is taken into account, the range of viable operation of such an engine is very narrow. This would render the whole concept of in situ hydrogen production through water electrolysis uneconomical in conjunction with engine operation, even though the presence of additional oxygen produced with the hydrogen tends, in principle, to improve engine performance beyond that observed with hydrogen addition. © 1999 International Association for Hydrogen Energy.     

Experimental and modeling study on ignition delay of ammonia/methane fuels

Ammonia mixed with methane is a potential clean fuel for engine applications toward a low carbon economy. Studies are scarce on ignition phenomenon for ammonia/methane fuels in literature. In the present study, the ignition characteristics for ammonia–methane–air mixtures have been investigated by both experimental measurements and numerical simulations. Ignition processes of a 60%ammonia/40%methane (mol%) fuel blend were investigated with shock-tube experiments. Measurements of the ignition delay times were performed behind reflected shock waves for such fuel/air mixtures with different equivalence ratios of 0.5, 1, and 2, at pressures around 2 and 5 atm within the temperature range of 1369 to 1804 K. Experimental results were then compared with numerical prediction results employing detailed kinetic mechanism, which showed satisfactory agreement within most of the range of the temperatures, equivalence ratios, and pressures investigated. Within the temperature range of 1300 to 1900 K, pressure range of 1 to 10 atm, equivalence ratio range of 0.5 to 2, and methane proportion range of 0% to 50% in fuel blends, the impacts of temperature, pressure, equivalence ratio, and methane additive were simulated on the ignition delay times of the fuel blends based upon the numerical model. It was found that the improvement of ammonia/methane ignition is significant with the increase of temperature, pressure, and methane additive while it is relatively not sensitive to equivalence ratio within the studied conditions. This suggests a promising potential of such fuel blends in real engine application. In addition to the calculations, reaction sensitivity analyses were also performed to have a deep insight into the observed differences between ammonia/methane/air ignition delay times with variation of conditions.     

Systematic optimization of a detailed kinetic model using a methane ignition example

An approach to systematic optimization of a large-scale dynamic method is presented. The method consists in parameterization of simulation results as response surfaces. The technique is exemplified by a shock-initiated ignition of methane.     

Comparative performance of coke oven gas,hydrogen and methane in a spark ignition engine

In this study, coke oven gas (COG), a by-product of coke manufacture with a high volumetric percentage of H₂ and CH₄, has been identified as auxiliary support and promising energy source in stationary internal combustion engines. Engine performance (power and thermal efficiency) and emissions (NO_x, CO, CO₂ and unburned hydrocarbons) of COG, pure H₂ and pure CH₄ have been studied on a Volkswagen Polo 1.4 L port-fuel injection spark ignition engine. Experiments have been done at optimal spark advance and wide open throttle, at different speeds (2000–5000 rpm) and various air-fuel ratios (λ) between 1 and 2. The obtained data revealed that COG combines the advantages of pure H₂ and pure CH₄, widening the λ range of operation from 1 to 2, with very good performance and emissions results comparable to pure gases. Furthermore, it should be highlighted that this approach facilitates the recovery of an industrial waste gas.     

Efficiency and emissions in a vehicle spark ignition engine fueled with hydrogen and methane blends

This paper shows the results of the tests carried out in a naturally aspirated vehicle spark ignition engine fueled with different hydrogen and methane blends. The percentage of hydrogen tested was up to 50% by volume in methane. The tests were carried out in a wide range of speeds with the original ignition timing of the engine. Also, lean equivalence ratios were proved. Just the fuel injection map was modified for each fuel blend and equivalence ratio tested. In this paper, the results of thermal efficiency and pollutant emissions achieved at full load have been compared with the corresponding gasoline test results. The best balance between thermal efficiency and pollutant emissions was observed with the 30% hydrogen and 70% methane fuel blend.