秦山二期600MW压力容器顶盖组件CRDM及热电偶管座冷装

核电站压力壳顶盖组件上CRDM和热电偶管座的冷装是整个产品的关键工艺之一 ,通过实物试验 ,验证管座冷装段浸入液氮后直径大小与时间长短的变化关系 ,并已按试验得到的结果成功地应用于产品的冷装。     

喷射正时和喷油持续期对正丁醇-正辛醇双燃料发动机性能的影响

将正丁醇、正辛醇分别作为预混合直喷燃料应用于双燃料发动机中,并利用KIVA4-CHEMKIN程序研究喷射正时和喷油持续期对正丁醇-正辛醇双燃料发动机燃烧及排放特性的影响。结果表明：喷射正时从5°提前到10°时,可以提高发动机的缸内平均压力、热释放率 （heat release rate,HRR）峰值和平均指示压力 （indicated mean effective pressure,IMEP）,减少CO排放量,但会使最大压力升高率和NO_x排放量增加。当喷射正时进一步提前到15°时,会导致机械损失增加,IMEP下降。延长喷油持续期可以降低缸内平均压力、HRR峰值、最大压力升高率和NO_x排放量,提高IMEP,但会使CO排放量先减少后增加。     

聚甲氧基二甲醚和汽油双燃料火花辅助压燃燃烧及排放试验研究

试验平台基于汽油缸内直喷（gasoline direct injection, GDI）发动机改造,缸内直喷聚甲氧基二甲醚（polyoxymethylene dimethyl ether, PODE）,进气道喷射汽油,并将压缩比从10提升至15以利于压燃,以点火和直喷策略作为控制参数,获取双燃料火花辅助压燃（dual-fuel spark-assisted compression ignition, DF-SACI）发动机的运行特征。试验结果表明：DF-SACI呈现多阶段放热,直喷正时提前可提高混合气均匀性,减小不同燃烧阶段的界限,放热率明显提高;直喷比例可以更为有效地调节CA50和等容燃烧的比例,对热效率影响明显;同时放热率受点火正时提前的影响最小。试验中有效热效率最高可达37.5%。排放方面,DF-SACI模式在合适的点火和喷射策略下,可在一定程度上降低HC和CO的排放,HC体积分数可降低至3 00010^-6以下,CO体积分数可降低至1 50010^-6以下,同时将NO_x排放控制在较低水平。通过对燃烧策略的合理调整,PODE/汽油双燃料发动机借助火花辅助压燃可实现高效清洁燃烧。     

气门座圈人工液氮冷却工艺压装试验研究

为解决采用液氮冷却工艺人工压装气门座圈时,气门座圈在液氮中冷却时间、从液氮中取出后装配完成时间均无设置依据的问题,进行气门座圈液氮冷却外径收缩及室温下外径恢复试验。结果表明：气门座圈最佳冷却时间为10 min,确保气门座圈与座圈底孔为间隙配合;气门座圈从液氮取出后需在1 min内完成装配,确保气门座圈与座圈底孔为过渡配合,提高气门座圈压装质量。     

轴承巴氏合金补焊试验研究

介绍了采用氧一乙炔补焊方法修复铸造轴承巴氏合金的工艺试验,通过试验数据和使用情况论证了补焊修复轴承巴氏合金的可行性.     

西德铜铅合金轴瓦材料的生产工艺概况

西德GLYCO 公司以生产铜铅合金轴瓦与轴套为主,此外还生产铝基合金轴瓦与轴套、巴氏合金轴承及塑料轴承等。铜铅合金轴瓦轴套用的双金属材料有带材连续浇铸、带材粉末烧结与离心浇铸等三种生产方法。该厂浇铸的铜铅合金化学成分是含铅22~(±3)%,锡1.5～     

离心浇铸巴氏合金轴瓦质量的改进

要获得优质的巴氏合金轴瓦，需要优质的轴承合金原料，合理的轴瓦结构设计和浇铸工艺。本文主要通过对加镉和镍等元素的锡基轴承合金的金相组织分析，相成份分析，显微硬度分析，以及对合金的各项物理一力学性能试验，比较了含镉镍巴氏合金与传统巴氏合金之间的区别；同时，对取得优良的铸造轴瓦所必需的结构，设计和离心浇铸工艺进行了探索并取得了实际数据。     

柴油机轴瓦巴氏合金浇注工艺优化及试验验证

针对目前采用传统巴氏合金浇注技术所浇注的大功率低速船用柴油机轴瓦性能难以达到工作性能要求,通过对巴氏合金的浇注技术进行优化研究,建立了轴瓦浇注工艺的优化模型,应用神经网络和遗传算法对优化模型进行了求解,获得了最优的浇注工艺参数,对采用新工艺浇注的轴瓦进行试验验证.结果表明,优化后的浇注工艺明显改善了轴瓦性能.     

巴氏合金轴瓦结合性能的检测

叙述了巴氏合金轴瓦结合性能的检测方法，通过试验轴瓦的各项结合性能试验，如Chalmers试验Chisel试验和微观组织检查等，对评定、改进浇铸工艺和提高产品质量具有实际意义。     

汽轮机巴氏合金轴瓦缺陷焊接修复的可行性

本文简述了巴氏合金的工作性能、要求。通过对用氧乙炔气焊修补巴氏合金轴瓦工作及试验、检测的总结,提出用焊补修复有缺陷的巴氏合金轴瓦可以保证轴瓦的工作性能不会下降,同时可以节约贵重金属。还介绍了具体的焊补工艺经验。     

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.