柴油机微粒捕捉器主动再生特性的计算与分析

对柴油机排气微粒捕捉器（DPF）的主动再生特性进行了研究,建立了DPF主动再生数学模型,具体分析了柴油机转速、排气中的氧气浓度、DPF的微粒沉积量、微粒的活化能以及柴油机排气温度等参数对DPF主动再生特性的影响。结果表明,通过适当推迟柴油机喷油提前角以提高其排气温度,并辅以燃油加剂或利用催化剂降低微粒的活化能,在适当的条件下,进行DPF的主动再生是可行的。     

模拟柴油机排气微粒的试验研究

为了改善柴油机排气微粒袋滤器性能试验的可控性及经济性，本文研制了一种微粒模拟装置，用以模拟柴油机的排气微粒。并采用气溶胶粒度电分析仪、扫描电镜、透射电镜等对模拟微粒影响柴油机微粒袋滤器性能的主要物理特性进行了测试，并与柴油机微粒的相应特性做了对比分析，证明所模拟的微粒具有与柴油机微粒相似的物理特性。因此可用本文研制的微粒模拟装置代替柴油机进行柴油机排气微粒袋滤器的性能试验。     

柴油机微粒和苯并（a）芘排放特性的研究

本作采用稀释取样法测量和研究了自然吸气、增压和增压中冷高速柴油机的微粒排放特性，同时对一台高速柴油机排气微粒中的苯并（ａ）芘也进行了分析研究。     

柴油机排气微粒过滤器性能的研究

本文报导了在发动机台架试验中,泡沫陶瓷柴油机排气微粒过滤器的性能随柴油机工况变化的规律,为微粒过滤器的优化设计提供了一些依据。文中的数据是利用485Q 柴油机在发动机台架试验中获取的。此柴油机的排量为2.27L;压缩比为20:1;标定功率为37kW(当转速在3000r/min 时)。因柴油机排气微粒中含有部分未燃燃料的液态颗粒,这部分微粒不易被波许烟度计反映出来,所以本验试用过滤式质量浓度测量系统来测量微粒的数量。关于试验系统的设计及质量浓度测量装置,本文作者已有较详细的报导。试验时所采用的过滤材料是泡沫陶瓷。泡沫陶瓷为堇青石质(主要化学成分为SiO_2、Al_2O_3、Fe_2O_3等),平均孔径为0.3～0.5mm,     

柴油机排气微粒静电捕集的初步研究

本文通过对柴油机排气微粒电阻率的测量及其微粒固有荷电量与电晕荷电量的比较,分析了用静电技术捕集柴油机排气微粒的可行性。用485Q型柴油机进行了排气微粒静电捕集器模型的台架试验,证实了柴油机排气微粒的固有电荷不能满足静电捕集的需要,而强化荷电是必需的。     

柴油机排气微粒旋流净化技术的初步研究

根据柴油机排气微粒净化的要求,研制了一台柴油机排气微粒轴流直流式旋流净化器,并对旋流净化器的净化特性进行了初步的理论分析和试验研究,研究结果表明,排气微粒旋流净化技术对净化柴油机排气微粒是有效的;柴油机运行工况及旋流子结构参数对排气微粒净化效率有一定影响;排气微粒的凝聚是微粒旋流分离净化的前提。通过对净化器结构的优化以及采取必要的微粒凝聚措施,相信会显地提高柴油机排气微粒旋流净化器的净化效率,利     

过滤体对柴油机排气微粒粒径分布的影响

建立了柴油机排气微粒测量装置,对泡沫陶瓷与壁流式蜂窝陶瓷两种过滤体前后的柴油机排敢中的微粒分布进行了测量,发现壁流式蜂窝陶瓷对不同大小的微粒都有较高的过滤效率,而泡沫陶瓷过滤体对微粒的过滤效率与流速、微粒大小及泡沫孔参数有密切关系。     

柴油机排气碳烟微粒稀释采样系统的研究

本文介绍了一种小型稀释采样系统和相应的试验结果。1.柴油机排放微粒的稀释采样系统柴油机排放微粒是以较高浓度随高温气体排入大气的。当高温排气受到环境大气冷却时,排气中的挥发性物质会发生冷凝,微粒间的碰撞也会产生相互粘连而聚合。为尽量真实地测出微粒排放参数,对排气进行稀释可以有效地防止测量过程中发生微粒的聚合和凝聚。     

柴油机排气微粒捕捉器燃气再生技术的研究

提出了一种新的柴油机排气微粒捕捉器的加热再生技术 ,即利用燃气与排气中的氧气燃烧清除微粒捕捉器中沉积的微粒 ;根据液化石油气的物化特性和排气中的含氧量 ,对这种方法的可行性进行了理论分析和试验验证 ;研制了一种以液化石油气为再生燃料的柴油机排气微粒捕捉器 ,并对燃气流量、过滤体内的微粒沉积量以及再生时间等影响因素进行了台架试验研究。     

6102BQ柴油机排放特性的研究

摘要本文研究了6102BQ型柴油机排气中有害气体和微粒的排放特性.测量了不同喷油提前角时的发动机十三工况废气比排放量,并对微粒排放量的评价方法进行了探讨,认为目前参照我国十三工况法进行试验和计算比较合适.按照十三工况法进行了微粒排放试验,着重研究改变喷油提前角对No_x、微粒质量和微粒成份的影响.试验结果表明:当喷油提前角从21°CA减少到18°CA时,NO_x排放量明显减少,十三工况比排放量降低27.5%、微粒质量浓度平均增加9.1%,微粒中碳的含量随提前角减少而增加.     

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

<正>~~     

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.