共轨式电子控制燃油喷射系统控制原理及故障检修

采用高压共轨电子控制系统降低柴油机排放,目前已经成为柴油机排放达到欧Ⅲ排放标准采取的一项重要措施.本文以日野E13C型发动机采用的新型共轨系统为例介绍了共轨系统的工作原理、故障维修的方法.     

柴油机共轨喷油系统匹配与计算模型

采用共轨式喷油系统是提高柴油机性能、降低排放污染的有效手段，也是适应更加严格的排放法规和改善发动机的性能的途径之一。分析了柴油机共轨式喷油系统的研究热点及发展趋势，结合燃油系统的特点，讨论了喷油压力、喷油速率参数对排放和工作过程的影响，介绍了共轨系统的多分支共轨管贴体网格及多分支计算模型，提出了共轨系统与柴油机进气、燃烧系统的优化匹配措施。     

现代车用柴油机电控共轨喷射技术综述

阐述了现代车用柴油机电控共轨喷射系统的发展目的、意义和现状。电控共轨喷射系统无论从降低车用柴油机排放和噪声,还是提高车用柴油机的动力性和经济性都具有很大优势,随着排放法规日趋严格,对动力性,经济性和驾驶性要求越来越高,共轨式电喷射技术必将是今后现代车用柴油机发展趋势     

电控高压共轨低排放D114柴油机的研制

在现已批量生产的D114柴油机的基础上,为满足欧Ⅲ排放法规的要求,研制开发了低排放的D114电控高压共轨柴油机。研究结果表明,电控共轨系统具有较好的应用适应性,可改善柴油机的整机性能,达到欧Ⅲ排放标准。     

共轨柴油机燃烧排放性能数值仿真研究

为了研究柴油机燃烧排放性能,建立共轨620柴油机包括进气道和燃烧室在内的三维几何模型,利用FIRE软件划分网格并且进行数值仿真计算,在喷油量一定的前提下分析共轨系统中各参数对柴油机燃烧与排放性能的影响。结果表明喷油提前角和共轨压力对整机性能的影响较大。增大喷油提前角和共轨压力、减小喷孔直径有利于改善燃烧排放性能。     

船用大功率柴油机共轨喷射系统匹配研究

为提高船用柴油机的性能,进行了高压共轨喷油系统与大功率柴油机的匹配研究。在分析柴油机基本参数的基础上,通过计算喷油系统结构匹配参数,设计了高压共轨系统共轨组件的结构参数。进行了原机和配机的仿真与试验研究,结果表明所匹配的高压共轨系统比原机的燃烧排放性能有明显改善。     

柴油机高压共轨技术研究

柴油机高压共轨技术因其柔性可调的突出特点使排放水平和性能得到有效提高.论述了高压共轨技术组成结构和工作原理,给出了传统柴油机的高压共轨改造系统匹配流程.     

柴油机共轨喷射系统的应用现状及发展前景

由于共轨喷射系统具有高度的控制灵活性，已在为降低柴油机排放的主要核心技术之一，本文简要介绍了近年来国外轿车和卡车柴油机上共轨喷射系统发展现状及前景。     

电控共轨喷油系统柴油机性能的研究

介绍了电控共轨喷油系统在柴油机上的应用;进行了直喷柴油机与电控共轨喷油系统的匹配试验;研究了共轨压力、喷油提前角及转速、负荷等工作参数对柴油机性能的影响。结果表明,对于不同的工况选择合适的共轨压力和喷油提前角,可以降低燃油消耗率和最高爆发压力,改善排放,达到对柴油机性能的综合要求。     

CA6110／125ZLRA5高压共轨电控柴油机的开发研究

阐述了高压共轨燃油系统的结构与工作原理 ,对原样机进行了性能与排放试验。在对共轨样机的试验中 ,通过改变共轨压力、喷油定时、预喷间隙和预喷量以及发动机的进气涡流比等参数 ,找出了这些参数对柴油机性能和排放的影响规律 :降低涡流比可使柴油机的烟度、颗粒度及标定点的比油耗明显改善 ;提高轨压可明显改善柴油机的烟度和比油耗 ;增大提前角可使烟度降低。对两种柴油机均进行了负荷特性、速度特性、排放特性试验 ,共轨样机与原样机相比烟度、比油耗明显下降 ;随着负荷的增大NOX 也大幅度下降。研究结果表明 :共轨发动机的各排放指标均超过了欧Ⅱ排放标准。     

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.