汽车排放物中NOx、HC和CO的预测模型研究

为更深入细致的研究汽车有害排放物的排放规律,提出了用以计算机仿真计算的柴油机排放物的数学模型。该预测模型是以现象学燃烧模型为基础的,NOx的数学模型用广义Zeldoich不平衡原理建立,HC和CO的数学模型采用化学平衡和反应动力学原理建立。用该模型计算了某型号柴油机的排放物,得到了这3种排放物在缸内的生成过程,并从它们的生成机理出发,分析了不同喷油定时对排放规律的影响,讨论了推迟喷油措施对降低排放物的效果。实机实验结果表明计算值与测量值吻合较好,并且都反映出相同的规律:NOx和CO的生成量随喷油提前角的增大而增大,而HC排放量随喷油提前角的增大而减少。     

汽车排放物中NOx、HC和CO的预测模型

为更深入细致的研究汽车有害排放物的排放规律,提出了用以计算机仿真计算的柴油机排放物的数学模型。该预测模型是以现象学燃烧模型为基础的,NOx的数学模型用广义Zeldoich不平衡原理建立,HC和CO的数学模型采用化学平衡和反应动力学原理建立。用该模型计算了某型号柴油机的排放物,得到了这3种排放物在缸内的生成过程,并从它们的生成机理出发,分析了不同喷油定时对排放规律的影响,讨论了推迟喷油措施对降低排放物的效果。实机实验结果表明计算值与测量值吻合较好,并且都反映出相同的规律：NOx和CO的生成量随喷油提前角的增大而增大,而HC排放量随喷油提前角的增大而减少。     

现象学燃烧模型在直喷式柴油机试验研究中的应用

本文介绍一种4区的现象学燃烧模型，它可根据小缸径直喷式柴油机实测示功图推求质量燃烧率与NOx排放浓度，文中依据LD1100型柴油机的试验结果，分析讨论了计算模型中各需选值的参数对推求结果的影响，并对比了用热力学模型或现象学模型求得的燃烧率的差别。     

柴油机排气波许烟度值和微粒排放浓度相关性的研究

本文通过对柴油机微粒排放浓度和波许烟度值进行分析，研究了微粒中碳粒浓度和波许烟度值的关系，并对经验公式进行了修正；分析了微粒中碳粒百分比含量与发动机负荷的关系。提出了用波许烟度值估算柴油机微粒排放浓度的方法。结果表明：波许烟度值和碳粒质量浓度之间能建立较好的数学关系，微粒中碳粒百分比含量随负荷的增加而增大，并与波许烟度值的变化趋势一致，通过测定的柴油机排气烟度值可以粗略估算微粒排放的质量浓度。     

柴油机排气波许烟度值和微粒排放浓度相关性的研究

本文通过对柴油机微粒排放浓度和波许烟度值进行分析，研究了微粒中碳粒浓度和波许烟度值的关系，并对经验公式进行了修正；分析了微粒中碳粒百分比含量与发动机负荷的关系。提出了用波许烟度值估算柴油机微粒排放浓度的方法。结果表明：波许烟度值和碳粒质量浓度之间能建立较好的数学关系，微粒中碳粒百分比含量随负荷的增加而增大，并与波许烟度值的变化趋势一致，通过测定的柴油机排气烟度值可以粗略估算微粒排放的质量浓度。     

柴油机燃用生物柴油的非常规气态排放试验研究

通过FTIR技术,对燃用混合不同比例的棉籽生物柴油的柴油机的气态非常规排放物进行了在线测量,对生物柴油排放的二氧化硫、醛类、苯类进行了分析。试验结果表明,生物柴油能够降低柴油机二氧化硫的排放;生物柴油对柴油机的气态醛类排放和苯类排放无明显影响,说明较低比例生物柴油的添加不增加柴油机气态排放的毒性。     

影响柴油机排放的基本因素

本文在有关参考文献的基础上，分析了影响柴油机气态排放物、碳烟和颗粒排放的基本因素，提出了降低柴油机有害排放物的措施，以期给柴油机的设计和使用引出新的思路     

影响柴油机排放的基本因素

本文在有关参考文献的基础上，分析了影响柴油机气态排放物，碳烟和颗粒排放的基本因素，提出了降低柴油机有害排放物的措施，以期给柴油机的设计和使用引出新的思路。     

车用直喷式柴油机微粒排放与排气烟度、碳氢化合物排放的关系

本文针对自然吸气式车用直喷柴油机６１１０的微粒排放与排气烟度、碳氢化合物的关系进行了试验研究。结果表明，柴油机的微粒排放可按简单的经验关系式根据排气烟度和碳氢化合物排放计算，算出的值和直接通过稀释排气并用滤纸采样法测得的值吻合较好。本算式可用于确定６１１０及类似柴油机按ＥＣＥＲ４９十三工况的微粒加权比排放量，而不必用复杂的微粒测量系统。     

风冷非道路柴油机排放特性研究

利用车载排放检测仪(SEMTECH)和电子低压冲击仪(ELPI)进行了某非道路风冷非增压柴油机的气态污染物的测量和排放颗粒物粒径及质量分布特征研究.试验按照非道路柴油机排放标准规定的工况进行测量.试验结果表明:试验用非道路柴油机气态污染物中NOx的排放较差;微粒数量排放均成单峰对数正态分布,积聚模态微粒数浓度随负荷增加而增大,随负荷的减小积聚模态的粒径分布向小粒径方向移动,变化规律与车用柴油机相似,但粒径整体要大于车用柴油机;不同粒径微粒的质量呈双峰分布,分别对应积聚模态和粗粒子模态,积聚模态微粒对总质量排放的贡献较大,但与车用柴油机相比分担率有所不同.     

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.     

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。     

Contents in Volume 23,2014

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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.