单缸柴油机实现国Ⅱ排放可行性及措施

根据cB19756--2005《三轮汽车和低速货车用柴油机排气污染物排放限值及测量方法》对排放时限的要求，结合企业生产及产品技术水平，对该排放标准的实现进行了可行性分析，同时提出了若干满足该标准要求的技术改进措施，认为：农用单缸柴油机虽然是技术含量较低的一种机型，但是，通过一定的技术改进提高，其排放性能能够达到国标CB19756—2005第Ⅱ阶段的排放要求。     

满足单缸柴油机国-Ⅱ排放的技术难题与对策

结合单缸柴油机产品特点,分析了国内外小功率段柴油机排放法规标准的限值变化,针对单缸柴油机结构特点、行业现状及技术问题,阐明了低排放高性能单缸柴油机的研发难度和需解决的问题,给出了单缸柴油机优化性能及降低排放的技术路线和对策.分析表明:通过柴油机喷油系统、换气系统与燃烧室结构优化设计和匹配,特别是提高单缸柴油机用喷油系统的性能,优化燃烧过程的机内净化措施能满足GB19756、GB20891的排放限值的要求.     

新闻

根据《新生产机动车污染申报检测机构管理办法》的规定,国家环境保护总局发布2006年65号公告,核准山东省内燃机产品质量监督检验站等13个检测机构承担新生产机动车排放污染申报检测工作。该公告核准该站的检测业务范围如下:三轮汽车和低速货车用柴油机排放限值:依据标准GB19756     

满足国Ⅲ排放标准的经济型柴油机的开发研究

结合具体柴油机机型,介绍了一种符合中国国情,满足车用轻型柴油机国Ⅲ排放标准的系统方案。通过对4100QBZL型柴油机关键系统进行设计改进,并用具有高泵端压力的PM型电调泵和电控冷却废气再循环(EGR)系统与之匹配,使该柴油机达到了国Ⅲ排放标准的要求,研究表明:运用"直列泵 电子调速器 冷却EGR"技术,可以实现车用轻型柴油机的国Ⅲ排放标准要求,给众多发动机企业国Ⅲ排放技术开发提供了一种参考。     

重型车用发动机WHTC与ETC瞬态测试循环试验对比研究

针对我国原重型柴油机排放标准对道路实际工况覆盖不全面,尤其不能全面反映城市车辆长期低速低负荷状态,北京地标在原GB17691-2005基础上增加对城市用重型车的WHTC循环的要求.本文利用一台国Ⅳ排放水平的柴油机,试验分析了同是瞬态测试循环的WHTC与ETC工况点的差异,发动机负荷及工作状态的差异.总结了最终导致两个循环比排放量差异的原因,阐述了增加WHTC对改善城市车辆或发动机排放的意义,以及增加WHTC对排放后处理技术所形成的新的挑战.     

中国小功率非道路用柴油机低排放技术路线的探讨

对国内外小功率段柴油机实现低排放的技术路线进行了分析,针对中国目前现状得出实现第三阶段排放及今后更高排放标准的技术路线:37kW以下功率段柴油机采用改进燃烧过程和降低机油消耗的机械优化+DOC技术或机械优化+电控喷油技术,生产企业通过提升生产条件及加强质量控制,特别是有效实现全负荷最大油量限制,可使批量生产的柴油机满足中国第三、四阶段排放标准的要求;为更有效控制批量生产产品的排放和性能使其满足更高的排放标准,需开展15~37kW小缸径多缸柴油机低排放技术研究和产品研发。     

ZS1115单缸柴油机达欧Ⅰ排放标准的改进措施及试验研究

本文介绍了ZS1115型单缸柴油机进行排放性能改进中使用的技术措施。通过改善进气涡流比、改进燃烧室形状、延迟供油定时、提高供油速率等改进措施,并进行优化匹配,降低了各项柴油机的排放,使该机型达到欧I排放标准。     

ZS1115单缸柴油机达欧Ⅰ排放标准的改进措施及试验研究

本文介绍了ZS1115型单缸柴油机进行排放性能改进中使用的技术措施.通过改善进气涡流比、改进燃烧室形状、延迟供油定时、提高供油速率等改进措施,并进行优化匹配,降低了各项柴油机的排放,使该机型达到欧I排放标准.     

降低单缸直喷柴油机排放的思路及有效措施

随着<非道路移动机械用柴油机排放限值及测量方法(中国Ⅰ、Ⅱ阶段)>节能减排标准的实施,我们对柴油机燃油喷射系统进行了优化改进,验证了一些能有效降低单缸直喷柴油机排放指标的措施,有利于达到国家标准要求.本文从柴油机燃油喷射系统的喷油泵、高压油管、喷油器的改进入手,对降低排放的措施进行原理分析和验证.     

浅议车用柴油机欧II和欧III排放标准之异同

针对我国重型柴油机和轻型车现行的GB17691-2001《车用压燃式发动机排气污染物排放限值及测量方法》和GB18352.2-2001《轻型车污染物排放限值及测量方法(II)》的排放标准以及将要实施的等效于欧III的第3阶段排放标准进行描述释义,并简述2个阶段标准之间在限值、测试方法和技术保证措施等之间的异同。     

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%.     

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.     

Contents in Volume 23,2014

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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.     

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.