实验室模拟高炉喷煤燃烧装置的设计

为制取未燃煤粉,计算未燃煤粉的燃烧率,利用内装耐火材料的耐热钢管模拟热风炉加热空气,在实验室模拟高炉风口煤粉的燃烧,设计了高炉喷煤模拟燃烧装置。与干馏法制取未燃煤粉相比,内置耐火材料的耐热钢加热空气燃烧装置制取的未燃煤粉的燃烧率高于干馏法。     

等离子高温无氧燃料重整装置的开发及试验研究

设计开发了新型的高温无氧燃料重整装置及试验系统,该高温无氧重整利用发动机废气加热及等离子辅助加热的方式来实现,装置结构设计简单紧凑且无须催化剂的介入。等离子加热易于控制、传热面积小易于保温绝热,可减少能量损失。将正庚烷的重整产物引入发动机中成功实现了RM-HCCI(Reformed molecule homogeneous charge compression ignition, RM-HCCI)燃烧,将RM-HCCI和汽油均质压燃(Gasoline HCCI, G-HCCI)燃烧进行对比研究。研究表明,重整后的小分子燃料可延迟着火,传热损失率和排气损失率更低,可以获得更高的指示热效率。     

基于PCCI燃烧模式下的工况扩展实现途径及参数耦合关系

压燃式发动机燃烧过程和排放直接受到燃烧室内燃油与空气的空间与时间分布状况影响,而油气混合的状况与燃油喷射参数息息相关。燃油喷射参数是燃烧边界条件的一部分,因此燃油喷射参数的优化是实现优化燃烧进程,降低NOx和Soot等排放不可缺少的手段之一。利用发动机燃油喷射参数实时控制系统试验研究了燃油喷射参数对压燃式发动机燃烧及排放的影响规律。同时结合燃料特性与燃油喷射参数藕合对压燃式发动机预混合压缩着火燃烧过程的影响,探索燃料特性与燃油喷射参数协同控制实现压燃式发动机高效清洁预混合压缩着火燃烧的潜力。     

空压站空气出口总管着火原因探析及改进

通过对空压站空气出口总管着火原因的分析和探究,制定出避免空压站空气出口总管着火故障的改进措施,并通过增加后部冷却器的方法,彻底解决了空气出口总管着火的问题。     

预燃室天然气发动机控制策略对比研究

为满足降本增效的原则和发动机稳定运行的需求，对预燃室天然气发动机控制策略进行对比研究，分析四种不同控制策略下气耗率﹑过量空气因数﹑排气温度﹑缸内爆发压力等发动机运行的主要参数。通过对比和综合考量，最终确定最为合理的一种控制策略，为预燃室天然气发动机控制策略的选择提供技术参考。     

新型燃烧器在锻造炉上的应用

我厂锻造炉原烧油改为烧天燃气，采用平焰烧咀，该烧咀具有加热速度快，工件加热温度均匀燃烧稳定，氧化烧损少，炉龄寿命长，充分利用烟气余热能使空气预热300℃，节省天然气热效率高。     

智能机车防寒加热装置的研究

铁路机车防寒技术是确保机车低温工作性能的关键,低温环境严重影响机车空气制动系统零部件及阀件正常工作,导致无法正常排污或内部气流通道堵塞。既有的防寒措施大多为加装保温套或者电阻丝持续加热,这样增加了加热成本,还可能造成电阻丝过热而出现加热套着火现象,后果不堪设想。本文以笔者工作经验为例,分析了该装置的应用意义及关键技术等内容,为今后机车更好的防寒加热工作提供参考。     

LNG/柴油发动机燃料供给系统设计

本文设计一套双燃料系统,并选用一款主流柴油发动机,对其进行燃料供给系统进行双燃料系统进行改装,加装柴油/双燃料燃气系统装置通过输气管路与储气瓶和发动机连接,起到转换、供气等功能,如此车辆不仅能够使用纯柴油模式工作,也能够使用柴油和燃气混合燃料模式工作。液化天然气经减压汽化后,与空气混合引入柴油气缸,依然按照原来发动机的压燃式着火方式进行燃烧,此种燃料供给系统基本不改变原来发动机的结构,即可实现LNG/柴油双燃料,或者纯柴油模式的燃烧[1]。当没有足够的LNG供应或者实际工况不允许使用双燃料模式,那么驾驶员,或者ECU控制单元可以将发动机切换至原柴油机工作模式,其改装简单,成本低,推广容易,目前本文采用此种发动机改装设计方法。     

发动机活塞顶部陶瓷组织和耐烧蚀性研究

为提高新开发的天然气发动机活塞的使用性能,改善活塞顶部出现的烧蚀等问题,对天然气发动机活塞顶部进行了硬氧处理和镀陶处理。通过SEM和XRD分别研究了其组织和物相的变化,并进行了活塞顶部陶瓷耐烧蚀性能和热冲击性能试验研究。结果表明:镀陶处理膜层存在均匀分布的放电通道,通道周围堆积有熔融的颗粒。主要物相为α-Al2O3、γ-Al2O3、SiO2和一定量的非晶相,以及莫来石(3Al2O3·2SiO2)。抗热蚀性能测试显示,未表面处理的活塞在加热到630s时,活塞顶部测温点温度达到433℃,顶面出现熔融现象;顶部硬氧的活塞在加热到660s时,活塞顶部测温点温度达到456℃,顶面出现熔融现象;顶部陶瓷活塞在加热到1350s时,活塞顶部测温点温度达到500℃,顶面出现熔融现象。可见顶部陶瓷活塞耐热性显著优于顶部硬氧活塞和未表面处理活塞。强化热冲击500次,陶瓷层未脱落,起皮,微弧氧化陶瓷层耐热冲击性良好。     

一种基于吸收式热泵的污泥烘干除湿系统

介绍了一种基于吸收式热泵的污泥烘干除湿系统,包括干燥机、空气降温除湿装置、空气循环风机、空气加热装置、溴化锂吸收式热泵。干燥机、空气降温除湿装置、空气循环风机、空气加热装置依次串联;空气降温除湿装置及空气加热装置分别与溴化锂吸收式热泵相连;设置冷却装置,当溴化锂吸收式热泵需要停机检修时备用。将溴化锂吸收式热泵作为污泥烘干除湿的动力热源和动力冷源,可以实现污泥烘干除湿的同时,回收污泥冷凝除湿过程中的热量,降低污泥烘干除湿过程中的能源消耗,提高了污泥烘干除湿的效率。系统运行经济,未造成空气的二次污染。     

复合中空热管传热性能研究

为了解决工业中的大量低品质烟气余热的回收利用和烟气酸露点腐蚀导致设备容易失效的工程问题,提出了一种复合中空热管传热元件,介绍了其结构及工作原理;对其内部传热机理进行了分析,并对其启动特性、等温性能和传热性能进行了试验研究。研究结果表明:复合中空热管在外管壁温度30℃时,加热时间2 min之内就能正常快速启动工作;在自然空气对流冷却条件下,具有较好的等温特性;复合中空热管的传热系数随着冷却水雷诺数的增加而增加;在加热蒸汽温度低于125℃的低温蒸汽加热条件下,当冷却水的雷诺数为6650时,复合中空热管的传热系数为1350W/(m2.℃)。试验研究结果为复合中空热管换热器的工程应用提供了基础。     

应用火花塞式传感器测量增压汽油机缸内压力

气缸压力是发动机的一个重要的指标,通过选举火花塞式传感器测量增压汽油机缸内压力,得出增压后发动机的工作状态及其增压效果。该传感器由一个小型点火电极和一压力传感件构成,其接收气缸压力的表面尽可能接近燃烧室,同时易受热影响的压电陶瓷传感元件尽可能近地置于火花塞温度最低的塞柱底座。避免了燃烧气体的纵向共振和热传递的影响。     

一种耦合燃气轮机的富氧燃烧系统技术经济性能分析

提出一种燃气轮机与富氧燃烧耦合的动力系统,该系统利用烟气排烟余热和锅炉内设高温受热面加热压缩空气,使其推动燃气轮机涡轮做功,用燃气轮机的压气机替代空分系统的压缩机,实现空分系统和动力系统耦合,同时燃气轮机也是烟气CO2压缩机的原动机。对新系统进行热力学与经济性分析,对应计算系统净供电效率和供电成本。结果显示当工质在锅炉高温受热面中的吸热量占燃气轮机热耗的比β为0.8、燃气轮机效率ηgt为0.32时,新型耦合系统净效率可比常规富氧燃烧系统增加4.2%,供电成本降低0.044元/(k W·h)。     

Control of cold start hydrocarbon emissions of motor bike engine by gasoline-ethanol blends and intake air heating

Two wheeled motor bikes are playing an important role in urban passenger transportation owing to ease of handling and affordable cost. Maximum amount of unburnt hydrocarbons (HC) and carbon monoxide (CO) are emitted during cold start of spark ignition engines. The current work presents the possible reduction of cold start HC emissions of 150 CC motorbike spark ignition (SI) engine with ethanolgasoline blends and/or with intake air heating by glow plug. Anhydrous ethanol was blended with unleaded gasoline in the range of 0% (E0) to 20% (E20) by volume to be used as fuel. The experimented parameters were intake air temperature, exhaust gas temperature, fuel consumption and exhaust gas emissions. Without intake air heating, E10 was found to be the optimum to reduce the cold start HC emissions by 23%. With intake air heating in the range of 40°C to 70°C, maximum HC emissions reduction was 23.8% for neat gasoline at 50°C and 33.6% for E10 blend at 60°C.     

Effect of water induction on the performance and exhaust emissions in a diesel engine (II)

This study was to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in an IDI diesel engine. The fuel injection timing was also controlled to investigate a method for the simultaneous reduction of smoke and NOx when water was injected into the combustion chamber. The formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water played a role as a heat sink during evaporating in the combustion chamber, while the smoke was slightly increased with increased water amount. Also, NOx emission was significantly decreased with increase in water amount. A simultaneous reduction in smoke and NOx emissions was obtained when water was injected into the combustion chamber by retarding more 2°CA of the fuel injection timing than without water injection.     

Comparisons of predicted and measured results on performance and emission of engine effected by intake air dilution and supercharging

An experimental study was conducted on a single cylinder direct injection diesel engine to investigate the effects of diluting intake air, with different gases and increasing intake pressure on combustion process and exhaust emissions. The intake O₂ concentration is changed from 15% to 21% by diluting intake air with different gases (CO₂, Ar, N₂), and the intake pressure is changed from one to two bar by a screw compressor. A modified program for calculating heat release rate, is used to study the characteristics of combustion and exhaust emissions in detail. The main results show that the addition of either CO₂ or Ar to the intake air increases the ignition delay. The variations of ignition delay with CO₂ are much larger than those of ignition delay with Ar for the same O₂ concentration. The emission of NOx decreases with the decrease of O₂ concentration and the smoke level is lower with the addition of the CO₂ than with that of Ar. As the intake pressure is increased, the ignition delay is shortened. Furthermore the high intake air pressure enhances the air-fuel mixing and diffusion combustion, and reduces the premixed combustion, so that NOx emission is decreased without increasing smoke emissions. The addition of CO₂ at high intake pressure, drastically reduces NOx emissions and smoke emission simultaneously at a high load condition, and the addition of CO₂ reduces NOx emissions without affecting the smoke emissions substantially at a low load condition. A zero-dimensional combustion simulation program incorporated with the present heat release correlation and ignition delay correlation is used to predict ignition delay, cylinder pressure and engine power. The results show that the correlations are likely to be adequate for the engine operating under diluted intake air and various intake pressure.     

四角切圆锅炉炉内煤粉燃烧过程数值模拟

利用计算流体动力学软件PHOENICS 3.5对一台200 MW四角切圆水平浓淡燃烧煤粉炉进行数值模拟研究,采用多流体两相流动模型及煤粉燃烧综合模型,计算得出在垂直方向不同二次风风量分布的工况下,炉内各截面处的烟气温度、燃料浓度、燃烧产物组分浓度以及炉内辐射热流的分布。结果表明,在燃烧器出口处出现了高煤粉浓度和烟气高温区,并出现气固两相分离的现象,使得煤粉着火及时,燃烧器区域维持较高温度,并防止水冷壁结渣,炉内温度、炉膛出口氧量和飞灰可燃物的计算结果和试验结果相比,吻合较好。二次风分级配风工况下,下部燃烧器区烟气温度升高,但氧气推迟混入,相应位置飞灰可燃物有所增加。计算模型能够合理地模拟水平浓淡煤粉气流在大型锅炉炉膛内的燃烧过程,适用于运行工况的优化和炉内污染物的控制。     

An experimental study on spray and combustion characteristics based on fuel temperature of direct injection bio-ethanol-gasoline blending fuel

This study investigated the spray and combustion characteristics of a direct injection spark ignition type system based on the changes in the temperature of the blended fuel (with bio-ethanol and gasoline). The test was performed in a chamber with a constant volume. The diameter and width of the chamber were 86 mm and 39 mm, respectively. The bio-ethanol test fuel was blended at volume ratios of 0 %, 10 %, 20 % and 100 %. The temperature of the fuel was set as −7, 25 and 35 °C. The fuel injection pressure and ambient pressure were set as 4.5 and 0.5 MPa, respectively. The shape and characteristics of the spray were investigated through a spray experiment. The increase in the fuel temperature changed its density and viscosity; this in turn increased spray penetration and spray area and increased the bio-ethanol blending ratio. The combustion visualization and experimental analysis indicated that the decrease in the fuel temperature and the increase in the bio-ethanol blending ratio led to the high viscosity and low heating value. This resulted in an increase in the ignition delay and a decrease in the rate of heat release. It is necessary to adjust the spray strategy and ignition timing to adopt bio-ethanol blended fuel as an alternative fuel.

     

Investigations on the effect of measurement errors on estimated combustion and performance parameters in HCCI combustion engine

Several parameters derived from heat release analysis are used for combustion diagnostics and control in internal combustion engines. It is important to tune the input parameters used in heat release calculations, in order to get correct estimation of heat release rate. In this study, tuning of input parameters is carried out by using cumulative heat release calculations of cylinder pressure during motoring. This tuning procedure uses offline iterative processing of motoring in-cylinder pressure data. The tuned parameters obtained from this method can also be utilized for online analysis of combustion parameters. Input parameters used in these investigations are intake air temperature, intake air pressure, phasing between the acquired pressure and crank angle position, compression ratio and scaling factor of heat transfer coefficient. Effect of error in these input parameters on estimated combustion and performance parameters like IMEP, combustion phasing, combustion duration, heat release rate, and maximum mean gas temperature are evaluated. The relative importance of measurement error in input parameters and its maximum expected error in the final results is analyzed in a HCCI combustion engine. Results shows that measurement errors in phasing between pressure and crank angle position, compression ratio and inlet air pressure affect estimated combustion and performance parameters significantly.     

An experimental and mathematical study on the effects of ignition energy and system on the flame kernel development

A constant volume combustion chamber is used to investigate the flame kernel development of gasoline air mixtures under various ignition systems, ignition energies and spark plugs. Three kinds of ignition systems are designed and assembled, and the ignition energy is controlled by the variation of the dwell time. Several kinds of spark plugs are also tested. The velocity of flame propagation is measured by a laser deflection method, and the combustion pressure is analyzed by the heat release rate and the mass fraction burnt. The results represent that as the ignition energy is increased by enlarging either dwell time or spark plug gap, the heat release rate and the mass fraction burnt are increased. The electrodes materials and shapes influence the flame kernel development by changing he transfer efficiency of electrical energy to chemical energy. The diameter of electrodes also influences the heat release rate and the burnt mass fraction.