一种可与风轮高效匹配的水泵设计

为使风力提水机组能够高效匹配，设计了变扭矩容积式叶片泵，其特点是扭矩变化与转速二次方成正比，从而满足了风轮的输出特性，使风力提水机组既有良好的启动特性，又可将设计风速提高，达到了从启动风速到额定风速区间基本能够在高效工况下匹配。     

风力提水机性能的改进

在同样叶轮直径,同样运行条件下可对变行程与不变行程风力提水机进行了对比实验,实验结果表明,在低风速度下,可变行程风力提水机的性能与不变行风力提水机相比差别不大;但在高风速下,可变行程风力提水机具有提水量大,效率高,泵运行转速稳定等优点,极具开发利用价值。     

基于运行曲线的机械式风力提水机组匹配性设计方法研究

为改善风力提水机组设计中的部件匹配性问题,提高提水机组运行效率,提出一种机泵分离式风力提水机组匹配性设计方法。通过各部件运行曲线之间的工作点追踪与交叉确定风轮、空气压缩机以及隔膜泵之间相匹配的最佳设计点。并依照该方法设计试验样机,通过对样机的监测,各个运行参数之间的相关性与理论一致,样机运行稳定。该匹配性设计方法可普遍适用于机泵分离式风力提水机组,提高机组的寿命和运行效率。     

YFT3—6风力提水机

YET—3—6风力提水机是由盐山县农机研究所研究设计的,机组由真空井和帆式叶片风轮机组成,具有侧翼、配重调速系统,使YFT—3—6风力提水机具有自动迎风、自动停车的特点。主要技术参数: 风轮直径3m;叶片数6片;风轮中心高度3m;起动风速2.5m/秒;额定风速8m/秒;工作风速范围3～8m/秒;叶片安装角度φ根45°;φ尖15°;额定转速60±15转/分;额定功率0.9马力;风能利用系数0.26～0.3(经验数字);配套提水机具:真空井,井头内径135mm;活塞行程85、110、130mm;吸程     

风力机-螺旋泵提水机组合理匹配的研究

机组匹配是否合理对风力提水机组的性能影响很大。理想的匹配应根据风力机输出轴和配套水泵的实测特性曲线确定。其关键,一方面要考虑在常用工作风速下,风力机输出轴的转速是否与配套水泵效率较高时的转速范围相适应,另一方面要考虑在当地年平均风速下,风力机输出轴提供的扭矩是否能满足配套水泵所需的工作扭矩。此外还要兼顾机组在低风速下的起动性能,高风速下的调速性能等因素。在综合分析基础上,计算选择合适的传动比,最后绘制机组配套性能曲线并进行检验。     

FTS-6型风力提水机组的研制与应用

一、前言根据国家计委和江苏省科委下达的“关于沿海滩涂风能利用示范试验及风力机具的研制”项目的要求,我们研制成功一种适合滩涂使用的FTS-6型风力提水机组,并于1987年3月通过省级鉴定,图1是其外形图。该机组结构新颖,匹配性能好,各项指标均达到计划任务书的要求。二、主要设计参数的确定FTS-6型风力提水机组主要性能参数: 风轮直径D=6米,风轮叶片为8片,叶片材料为聚乙烯单面     

Gurney襟翼对风力提水机风轮性能影响的数值模拟

风力提水机在我国经过严格的生产考核运行和多年的实际应用,产品质量基本可靠,有些机组的水平达到或处于国际领先地位。针对风力提水机的应用,在来流风速3~14m/s、攻角4°~14°范围内,对装有不同高度襟翼的风轮采用Fluent软件进行模拟计算,比较分析其气动性能和叶片周围流场分布的差异,研究Gurney襟翼的增升原理。结果表明,Gurney襟翼有效增加了风轮的输出功率,特别是在大攻角、较高风速情况下,其中2%弦长高度的襟翼增升效果最好,并分析获得风轮输出功率增大的主要原因为襟翼后方出现的卡门涡街和襟翼前面的角涡。     

小型风力提水机的低实度风轮设计及其数值模拟

针对传统风力提水机实度大、风能利用率低的缺点,采用NACA4412航空翼型及叶素动量理论对小型风力提水机叶片的气动外形进行设计,采用6叶片风轮形式,引入修正因子,并根据工程实际优化了叶片的弦长及安装角,并采用CFD方法对风轮进行数值模拟。结果表明,设计的风力提水机在2.8 m/s的微风下可起动,在额定工况下风能利用系数达0.43,叶片具有很好的三维流动特性,风能利用系数高,降低了传统风力提水机风轮的实度,扩大了风能的利用范围。研究结果对风力提水机的改进设计有指导意义。     

风力离心泵提水机组的匹配特性及其影响因素

分析了风力离心泵提水机组的匹配特性，探讨了传动比，管路损失和扬程对匹配特性的影响。     

风力发电机大风限速保护方法的研究

小型风力发电机面临的最大难题是其可靠性问题,即大风时的限速保护问题.从能量守恒的角度分析了利用风轮与发电机的功率匹配特性实现风力发电机限速保护的可行性.另外,设计了2台风轮与发电机具有不同匹配特性的300 W/26 V风力发电机,为了使其具有可比性,使用了同样型号的发电机.通过实验测试了风轮的机械输出特性、发电机在输出电压不同时的功率特性和整机的功率输出,实验结果表明,风速12 m/s以下时2台风力机输出功率基本相同,风速12 m/s以上时其中1台随着风速的增加功率不断增加,而另外1台随着风速的增加输出功率不再上升,甚至有点下降,与大风机功率特性相似.     

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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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.