Electronically Controlling the System of Preheating Intake Air by Flame for Diesel Engine Cold-Start

In order to improve the cold start performance of heavy duty diesel engine, electronically controlling the preheating of intake air by flame was researched. According to simulation and thermodynamic analysis about the partial working processes of the diesel engine, the amount of heat energy, enough to make the fuel self ignite at the end of compression process at different temperatures of coolant and intake air, was calculated. Several HY20 preheating plugs were used to heat up the intake air. Meanwhile, an electronic control system based on 8 bit micro controller unit (MCS 8031) was designed to automatically control the process of heating intake air. According to the various temperatures of coolant and ambient air, one plug or two plugs can automatically be selected to heat intake air. The demo experiment validated that the total system could operate successfully and achieve the scheduled function.

Intelligent prediction on air intake flow of spark ignition engine by a chaos radial basis function neural network

To ensure the control of the precision of air-fuel ratio(AFR)of port fuel injection(PFI)spark ignition(SI)engines,a chaos radial basis function(RBF)neural network is used to predict the air intake flow of the engine.The data of air intake flow is proved to be multidimensionally nonlinear and chaotic.The RBF neural network is used to train the reconstructed phase space of the data.The chaos algorithm is employed to optimize the weights of output layer connection and the radial basis center of Gaussian function in hidden layer.The simulation results obtained from Matlab/Simulink illustrate that the model has higher accuracy compared to the conventional RBF model.The mean absolute error and the mean relative error of the chaos RBF model can reach 0.0017 and 0.48,respectively.

Techno-economic feasibility assessment of a diesel exhaust heat recovery system to preheat mine intake air in remote cold climate regions

Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter.The cold fresh air of those remote areas can be as severe as
40℃ and commonly needs to be heated to around+3℃.This extensive amount of heating is usually provided by employing large-size air heaters,fueled by diesel,propane,natural gas,or heavy oil,leading to high energy costs and large carbon footprints.At the same time,the thermal energy content of a diesel generator sets(gen-sets)exhaust is known to be one-third of the total heating value of its combusted fuel.Exhaust heat recovery from diesel gen-sets is a growing technology that seeks to mitigate the energy costs by capturing and redirecting this commonly rejected exhaust heat to other applications such as space heating or pre-heating of the mine intake air.The present study investigated the possibility of employing a simple system based on off-theshelf heat exchanger technology,which can recover the waste heat from the exhaust of the power generation units(diesel gen-sets)in an off-grid,cold,remote mine in Canada for heating of the mine intake air.Data from a real mine was used for the analysis along with environmental data of three different location-scenarios with distinct climates.After developing a thermodynamic model,the heat savings were calculated,and an economic feasibility evaluation was performed.The proposed system was found highly viable with annual savings of up to C$6.7 million and capable enough to provide an average of around 75%of the heating demand for mine intake air,leading to a payback period of about eleven months or less for all scenarios.Deployment of seasonal thermal energy storage has also been recommended to mitigate the mismatch between supply and demand,mainly in summertime,possibly allowing the system to eliminate fuel costs for intake air heating.

Application Research of Intake-Air Cooling Technologies in Gas-Steam Combined Cycle Power Plants in China

The generated power and efficiency of gas-steam combined cycle (GSCC) power plants depend on the temperature of the inlet air greatly. Based on the analysis of basic theory of inlet air cooling technologies, the application of evaporative cooling system and the absorption cooling system in GSCC power plants are discussed in this paper. Moreover, in China with high temperature and humidity, applied research and simulation analysis of the above two different cooling systems are conducted separately, the research results of which can provide certain reference for optimal design and economic operation of inlet air cooling system for GSCC power enterprises in China.

地下进风系统对间接空冷塔性能的影响

削弱环境风对间接空冷塔散热器性能的不利影响,有助于其安全和经济运行。该文提出一种新型间接空冷塔地下进风系统,将空冷散热器整体布置在低于地表平面的地下空间内。建立配置地下进风系统的间接空冷塔数值计算模型,得到间接空冷塔的空气流场特性和热力特性。基于凝汽器和空冷散热器协同调节、相互制约的作用机制,采用机理模型和数值模拟相结合的方法建立排汽压力的计算模型,在此基础上计算地下进风系统的热经济性。结果表明,在4 m/s风速下,虽然迎风扇段空气流量减少14.5%,热负荷降低12.4%,但侧风扇段和背风扇段冷却空气量分别增加46.0%、8.0%,热负荷分别提升30.9%、3.2%。在高风速工况下,地下进风系统削弱环境风对排汽压力的影响,具有抵御自然大风的能力。某660 MW间接空冷机组,采用地下进风系统全年可节约标煤9554.3 t,节省燃料费1094.0万元。

输水管线空气阀进排气孔径的合理选择

输水管线空气阀进排气孔径的选择,包括防水锤型空气阀低压进排气孔、缓冲板小排气孔和高压微量排气孔,不仅影响输水的安全性,而且严重影响工程投资。为了合理选择各种类型空气阀进排气孔径,本文首先提出了气体流量与流量系数、孔径、气压的函数关系,以及输水管液柱弥合水击压力与输水管直径、水击波速和空气阀流量改变量的函数关系;然后,建立了空气阀进排气孔径与输水管线充水和排水流速、负压控制要求及水击压力之间的函数关系,同时考虑了管材刚度和位置高程的影响。最后,分别以重力流输水管线和泵站加压输水管线为例,应用所得理论公式分别计算确定了复合式空气阀和防水锤型空气阀进排气孔孔径,结果表明按照本文公式确定的空气阀进排气孔径,不仅比按照常规经验确定的空气阀孔径小得多,而且可以有效削减输水管的液柱弥合水击压力。

高炉煤气的CCPP发电系统运行特性分析

以燃用高炉煤气的燃气蒸汽联合循环发电系统为研究对象,分析了燃气轮机进气温度、负荷和排烟温度及汽轮机负荷之间的关系。当燃气轮机进气温度低于-16℃时,汽轮机负荷降低12 MW;当燃气轮机进气温度超过20℃时,燃气轮机最高负荷约105 MW,比额定负荷低4 MW。燃气轮机进气温度过高或过低均会使系统的经济性变差。采取加热或冷却的措施维持燃气轮机进气温度在合理范围,可实现燃气蒸汽联合循环发电系统经济运行。

后向台阶-楔体结构对含硼固体火箭超燃冲压发动机燃烧性能影响

为增强含硼固体火箭超燃冲压发动机中空气与燃气掺混,提升火焰稳定性及燃烧效率,在一次燃气侧向进气基础上,补燃室前段增加后向台阶-楔体组合结构,采用数值模拟的方法分析一次燃气进气方式及楔体结构对含硼固体火箭超燃冲压发动机补燃室内燃烧性能的影响。结果表明:当补燃室结构不变时,一次燃气进气位置到后向台阶的距离从0.5d变化到6d时,硼颗粒燃烧效率先增大后减小,在一次燃气进气位置距台阶为1.25d时,硼颗粒燃烧效率最大,为48%;当一次燃气进气角度在45o~170o内时,一次燃气进气角度越大,发动机燃烧效率越高,一次燃气进气角度为170o时总燃烧效率最大,为71.32%;在一次燃气进气方式不变时,取楔体高度与台阶高度之比分别为0.40、0.50、0.55、0.60、0.65、0.70、0.75、1.00,随着比值增大,总压恢复系数减小,硼颗粒燃烧效率先增大后减小,当楔体高度与台阶高度之比为0.60时,硼颗粒燃烧效率最大,为53.2%。

汽车发动机产业技术专利信息分析

针对汽车发动机产业技术专利信息的发展,本文对汽车发动机产业技术领域的国内外专利进行检索和分析。借助incoPat专利数据库检索和专利导航,比较分析方法,对汽车发动机产业技术专利申请的总体趋势、技术构成、技术专利活跃度和主要申请人进行分析。采用图表展示分析对象在各技术分支方向的专利数量分布情况,了解分析对象所覆盖的技术类别以及各分支技术的创新热度。分析结果表明,汽车发动机产业技术国内外专利申请总量为142511件,申请量总体发展趋势主要分成三个阶段,中国相关技术专利申请量的全球占比为31.81%,高于其它国家。高价值重点专利主要集中在美国、德国、法国、英国、日本、韩国等发达国家,且在全球范围内分布广泛,覆盖热点和重点技术分支。

新型船用底部进气式脱硫塔流场分析

为改善船用脱硫塔内吸收液与烟气的交互程度从而达到提高脱硫效率的目的,将侧进气改为底部进气,加入聚气环和环状导流板,设计一种新型船用底部进气式脱硫塔。基于有限体积法和欧拉-拉格朗日法建立仿真模型。通过Fluent软件对船用脱硫塔正常工作时的内部流场进行仿真分析,以烟气流速分布均匀性和流动阻力为评价标准对比原始模型和改良模型。结果表明:改良模型的烟气流速分布均匀性比原始模型的提升了70%~85%,而流动阻力增加了约25%。

Feasibility Research on the High Speed Rotary Positive Air Filter

The structure, separation principle and feasibility research for a new type of vehicle air filter called the high speed rotary positive air filter were described. The analysis of the experimental data showed that the principle and structure of it were feasible and it possessed high separation efficiency and great self cleaning ability. Compared with the conventional air filter it also has lower air intake loss. So it is worth further practical research.

耦合溴化锂制冷机组的燃气-蒸汽联合循环性能分析

燃气-蒸汽联合循环机组的运行性能容易受到环境温度的影响,使得机组在电力负荷需求高峰期面临出力不足的问题.为了解决这一问题,基于EBSILON软件,对耦合溴化锂制冷机组的SGT5-4000F型燃气-蒸汽联合循环进行仿真建模,并将冷却装置加装到压气机入口处,模拟分析进气温度对联合循环输出功率和循环效率的影响规律.研究表明:通过改变压气机进气温度可知降低进气温度可使得联合循环发电功率提高4.73%-6.10%.在温度较高的夏季工况,在燃气轮机的压气机进气口处加装进气冷却装置可以提高机组的性能,并且温度越高,联合循环输出功率提高的效果更好.

燃气轮机进气过滤系统的技术现状与展望

燃气轮机因其高效的能源转化能力,在电力、航空、船舶和重型车辆等领域应用广泛,进气过滤系统作为燃机的关键设备之一,对其安全、稳定、高效的运行具有关键作用。首先分析了燃机进气过滤系统的功能及对机组的影响,随后从材料、结构、评价指标等方面介绍进气过滤系统的技术现状,最后对近年来快速发展的新技术在进气系统中的应用进行了展望。

带有镶铸筋板的燃气轮机进气缸的质量改进

介绍了带有镶铸筋板的燃气轮机进气缸铸件的结构及技术要求,针对铸造生产中进气缸铸件质量不稳定,容易出现渣孔、砂眼缺陷,镶铸件根部出现冷隔、融合不良等现象,分析了铸件缺陷产生的原因。通过将浇注系统改为全开放式,降低了内浇道流速,使夹砂缺陷得到有效控制;通过附加铁液流动通道,确保铁液充型平稳,提高了铸件外观质量;通过利用辅助浇道,将内浇道尽可能引到镶铸件附近,提高镶铸件链接部位的熔合质量,减少了镶铸件根部的冷隔、熔合不良缺陷。

运行参数对高温燃料电池物质分布与启动时间的影响研究

使用comsol软件,建立高温质子交换膜燃料电池电化学传热传质三维数值模型,通过改变电池的电压和入口温度,分析运行参数对电池内物质分布以及启动时间的影响。结果表明,随着进气温度的升高和电压的降低,电池反应物的消耗量及水的生成量在不断增加,启动时间也随之缩短。电压低于0.4V以下时,会导致阴极氧气不足产生“饥饿”现象。并且当进气温度高于150℃时,提高进气温度对启动时间的影响会大幅减少。即0.4V的启动电压及150℃的进气温度是一个比较合适的启动参数。

千瓦级风冷燃料电池堆性能的研究分析

风冷燃料电池较传统的质子交换膜燃料电池简化了冷却及供气系统,使其便携性能得到了极大的提高,但是对于风冷电堆的研究大部分趋向于小功率,本文设计、测试、研究了2kW的风冷燃料电池堆的性能,探究了实测风量和理论风量的关系,温度的分布情况以及氢气进出方式对电堆性能的影响。研究结果表明:电堆的实际风量仅为最大风量的80%;电堆的温度分布不均匀,靠近双极板或者电堆中间部分的温度较高;此电堆单电池片数为68片,最大功率达到了1.92kW;单进单出相对于双进双出氢气进出方式,电堆功率相当,但是电压一致性更好。

环境温度对PG6111FA型燃气轮机影响的分析

针对燃气轮机机组在夏季高温环境下长时间运行时,无法达到进气温度的要求,造成机组出力严重受限,影响其调峰能力的问题,文章以PG6111FA型燃气轮机机组为例,分析环境温度对燃气轮机负荷影响的原因及对联合循环发电机组出力的影响,并提出利用进气冷却装置对压气机进气温度进行冷却来提高燃气轮机出力的解决措施。

基于CPFD多密度电子垃圾颗粒分离影响因素研究

基于电子垃圾中稀贵金属绿色、高效以及低能耗的分离回收需求,利用CPFD(计算颗粒流体动力学法),Barracuda气固耦合仿真分析软件建立电子垃圾颗粒气固分离模型,由于一次气流导致电子垃圾中稀贵金属颗粒分离效果不佳,颗粒混合度高,稀贵金属颗粒的品位和回收率较低,在一次气流基础上,引入二次气流,实现电子垃圾颗粒在竖直方向上的二次梯度分离,模拟电子垃圾中稀贵金属颗粒在两次气流作用下不同颗粒流的迁移轨迹、运移规律和稀贵金属颗粒的分选特性,探讨在两次气流参数、物料下落流量以及颗粒粒径下电子垃圾中稀贵金属颗粒的分离效率,包括品位和回收率。研究表明,多密度电子垃圾颗粒干法分选模型可以有效富集电子垃圾中稀贵金属;电子垃圾颗粒下落流量与颗粒粒径对稀贵金属的分离有显著影响,当一次进风的气流速度为3.8m/s、二次进风的气流速度为4.6m/s、入料开口宽度为4mm、两次气流开口宽度均为35mm、颗粒粒径为75~100μm时,Au的品位和回收率可达87.1%和99.1%;Cu的品位为70.8%,回收率为85.8%,富集比为35.4。说明在一次气流和二次气流的共同作用下,改变电子垃圾颗粒的入口流量、控制颗粒的粒径大小可以有效提升电子垃圾中稀贵金属的品位和回收率,同时对多密度颗粒多梯度、高精度的干法分选提供参考和借鉴。

基于CFD的大学生方程式赛车发动机进气系统设计优化

基于大学生方程式汽车大赛规则,为大学生方程式赛车赛用发动机春风650设计全新的进气系统。基于CFD方法,针对6000转高转速工况下发动机进气系统进行研究。采用ANSYS Fluent对进气系统进行瞬态三维流场仿真,时间步长设置为0.0005 s。湍流模型选择为realizable k-ε湍流模型,Velocity-inlet速度设置为15 m/s,压力为标准大气压;pressure-outlet采用expression设置压力波动函数,进气压力曲线由实际测量得出并拟合为正弦函数。对仿真结果进行后处理,主要对出口质量流量曲线、进气道内速度矢量分布图和压力云图进行分析研究。通过流场分布得到如下结果:气流在进气系统内呈现出旋转的趋势,弯曲的管道中易形成螺旋气流。进气系统中的压力波动周期循环,且稳压腔内部压力梯度较小。设计的进气系统有效提升了进气量,改善了安装限流阀后发动机的性能,能够提升发动机在比赛工况下的工作性能,为FSAE进气系统设计提供了理论指导。

煤矿井下通风系统设计及应用效果研究

针对某煤矿通风系统存在的主井进风量过大、主斜坡道进风量不足、部分区域存在漏风、回风系统风阻损失较大的问题,采取加设密闭墙并联运行空气幕,调整回风风机工况,优化通风通道,修复密封墙,清理总回风通道的措施,提升了通风系统效率,井下风量和空气质量得到保障。