浅析电控高压共轨燃油喷射系统中轨压的判定

本文重点介绍了共轨系统的轨压建立和故障模式分析,并通过对共轨系统油路和电路的建立和分析,能够快速查找共轨系统轨压的故障模式,及时解决影响共轨柴油机的正常工作问题。     

基于BP神经网络的GD-1高压共轨系统的建模研究

基于GD-1高压共轨燃油喷射系统,运用BP神经网络理论对GD-1系统高压油泵及共轨管进行建模,在Matlab平台上利用实际测得的数据对所建的神经模型进行训练,利用Simulink工具将训练好的高压油泵及共轨管模型与GD-1控制策略连接在一起进行闭环仿真,仿真结果表明设计的神经网络能很好地模拟共轨管内实际油压变化.     

高压共轨系统压力采样及其故障模式研究

对高压共轨系统压力调节原理进行了阐述,并在此基础上对轨压采样技术进行研究,分析了定时及定相位采样技术的优缺点,并研究定时及定相位采样对压力控制的影响。研究压力控制的各种故障模式,并分析故障源及判断方法,并从工程应用角度出发提出各种故障模式应急处理技术,从而为高压共轨系统市场化奠定基础,最后进行了试验。     

高压共轨系统限压阀试验研究

在电控高压共轨系统研究的基础上,对共轨管部件限压阀进行了试验研究,并对试验结果进行了分析,最后对自主开发的限压阀特性进行试验,并提出压力控制故障模式下的程序运行流程,从而为共轨系统故障诊断奠定了基础。     

基于专家系统的共轨柴油机实时诊断系统开发

在电控共轨系统开发的基础上,应用专家系统基本原理,对共轨系统故障诊断知识进行了合理分析,确定了共轨系统主要故障类型及判断方法,并在实际共轨系统上利用K线接口实现了与车辆诊断仪通讯功能。台架试验结果表明,实时诊断系统能对共轨柴油机主要故障进行可靠判断。     

高压油管对共轨系统性能影响的研究

归纳分析了高压共轨系统的数学模型,并选用FLOWMASTER建立了软件仿真模型.在发动机转速1 000 r/min、轨压110 MPa下,计算高压油管长度、直径、限流阀对系统性能的影响,并研究了小脉宽时的喷油特性.研究结果表明:系统内存在由喷油引起的压力波,高压油管长度为400 mm、直径3 mm时,系统阻力损失较小且响应迅速.流量限制阀有稳定管路压力波动的作用,小控制脉宽时平均喷油压力很低,控制脉宽为0.08 ms时,压力室压力小于3 MPa,不利于燃油雾化.     

高压共轨燃油喷射系统压力波动特征研究

在实验数据验证仿真模型正确的基础上,确立了高压共轨喷油系统GT-Fuel的仿真程序,分析了高压共轨燃油喷射系统波动特征,主要包括共轨系统各个零件尺寸的影响及共轨系统特性参数的影响,得到了各零件的最佳设计参数.     

基于Simulink的共轨柴油机怠速控制系统模型化开发方法

新一代汽车电控系统交联复杂,针对传统高压共轨柴油发动机控制系统开发模式,研究了使用MATLAB/Simulink软件进行模型化设计开发的方法和流程;对高压共轨柴油发动机怠速控制系统进行实例分析,实现了模型设计、仿真验证和代码自动生成等功能;进行了代码分析和模型仿真验证.结果表明,基于模型的高压共轨柴油机怠速控制系统研发...     

电控共轨系统限压保护标定

限压阀在共轨系统中承担零部件保护作用,油轨压力异常冲高时会导致限压阀开启。首先明确某机型共轨系统限压阀开启的边界条件,提出针对轨压控制中积分冻结功能的优化标定、故障模式下使用发动机限制扭矩功能的方案,并完成了供油系统台架验证试验,极大地降低了限压阀开启风险。     

高压共轨柴油机喷油器电磁阀故障诊断系统设计

根据电磁阀驱动回路仿真及试验,得出了高压共轨柴油机喷油器电磁阀在正常工作时以及短路、断路等各种故障状态时的驱动电流特性。根据对这些情况下驱动电流特征的对比,采用软件与硬件相结合的方法,设计了高压共轨柴油机喷油器电磁阀实时故障检测系统。该系统能够检测电磁阀的不同故障并且能在电磁阀故障时实现ECU的自保护功能。试验证明,该方法是一种实用而且快速的电磁阀故障检测方法。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.