摩托车催化转化器性能台架评价方法研究

台架评价试验在摩托车催化转化器性能评价体系中起重要的作用，但国内摩托车催化转化器性能台架评价目前尚属空白。在借鉴国内外汽车催化转化器台架评价试验方法的基础上，建立了摩托车催化转化器性能台架评价试验装置，并进行了催化转化器空燃比特性、空速特性、温度特性、起燃时间特性试验。     

摩托车催化转化器性能台架评价试验研究

台架评价试验在摩托车催化转化器性能评价体系中起重要的作用。根据摩托车催化转化器的特点，参照汽车催化转化器台架评价试验方法，建立了摩托车催化转化器性能台架评价试验装置，用该装置进行了催化转化器空燃比特性，空速特性，温度特性，起燃时间特性等试验，为摩托车采用催化转化器提供了有效的技术支持和评价手段。     

某汽油机歧管式催化转化器结构设计与分析

采用一维和三维联合仿真的方法选择汽油机歧管式催化转化器最优设计方案.通过一维数值模拟方法计算该汽油机不同转速下的性能,通过三维CFD仿真计算最大功率点该歧管式催化转化器的总压损和速度分布,综合对比了两种方案下汽油机整机性能、排气歧管流通性与均匀性、氧传感器处及催化转化器前端气流分布,基于分析结果确定歧管式催化转化器最优设计方案.     

摩托车汽油机排气催化转化器试验研究

本文介绍了国内和气油机排气催化转化器技术的现状,对QM500W型木兰摩托车用二冲程汽油机进行了排气催化转化器的设计,并在发动机台架上进行了试验研究。     

三效催化转化器快速老化过程性能仿真

基于三效催化转化器详细化学反应机理以及老化机理,建立了包含老化过程的三效催化转化器表面动力学模型,并与CFD软件相耦合,根据100h快速老化试验条件,建立了三效催化转化器快速老化过程的二维单孔道老化特性模型.对该模型进行数值仿真,得到了特征转化效率随快速老化时间的变化规律以及老化前后三效催化转化器的起燃特性、空燃比特性曲线.结果表明:仿真结果与试验结果基本一致,这为三效催化转化器的老化过程性能分析提供了有效的理论方法.     

排气含氧量对催化转化器净化率的影响

本项研究是用美国和国产的两种催化转化器在492Q-A型汽油机上进行的.试验表明,排气含氧量影响催化转化器对排气排放物NO_x,CO,HC的净化率.本文主要介绍了这一试验研究的装置、方法和结果.试验结果给出了不同的催化转化器在排气含氧量变化时,其净化率的变化趋势,从而可以把空燃比调整在适当范围内,以提高催化转化器对排气排放物的净化率.     

基于优化尿素液滴蒸发特性的SCR混合器

从改善尿素溶液蒸发速率方面对一款选择性催化还原(SCR)系统催化转化器的混合器结构进行改进设计,提出一种由半球型和百叶窗组成的新型混合器结构.基于连续相与离散相的耦合计算,对改进前、后的催化转化器内部流场进行数值模拟,结果表明:新型混合器结构能显著提高尿素液滴的蒸发性能,改善催化转化器载体前端气流和氨(NH_3)蒸气分布的均匀性;采用新型混合器结构的催化转化器可使NO_x转化率较改进前明显提高,催化器内部基本无尿素结晶产生,满足国Ⅴ排放要求.     

江南风光车排气系统设计研究

针对江南风光车尾气后处理的实际情况,从降低发动机冷起动时HC排放的角度,运用HC吸附式催化转化器与主催化转化器相结合的排气系统,通过分析软件,对排气管径分别为50,60,70 mm的催化转化器壳体内的气流的流场特性进行分析,结果表明在相同的催化器锥角条件下,排气管管径为50 mm时,催化转化器内气体的流速最均匀,从而能达到较高的废气转化效率,经试验,排放优于欧Ⅱ标准的要求。此外,本文对消声器进行了设计,采用阻抗复合型两级消声器。     

基于RBFNN与CMGA的催化转化器劣化预测

应用径向基函数网络(RBFNN)和压缩映射遗传算法(CMGA)的融合理论,提出了车用催化转化器劣化的在线预测策略.利用催化转化器劣化试验数据作为RBFNN的输入,影响催化转化器劣化的性能参数作为RBFNN的输出,进行了车用催化转化器劣化的模糊预测.利用RBF-CMGA融合预测策略,进行了车用催化转化器的空燃比特性、起燃比特性的劣化试验.结果表明: CO、HC和NOx的劣化系数分别为1.27、1.48、1.03,验证了该融合预测策略具有较好的分辨率,可用于车用催化器在线劣化预测.     

汽油车用催化转化器综述

本文着重于综述催化转化器的结构、设计中的关键性技术以及影响其性能的因素和解决措施。     

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。     

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.     

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.