小型太阳能—风力发电联合演示装置的设计

针对太阳能光伏和风力等新能源发电技术的科普及相关教育教学应用需求,设计开发了一种新型的便携式小型太阳能-风力发电联合演示装置,该装置同时采用了垂直轴/水平轴两种风力发电机和晶体硅太阳能电池,组成太阳能-风力发电联合发电系统,并基于MCU开发了演示控制系统,可以实现对不同风机和太阳能系统的发电演示,并通过对比实验室验证了装置的准确性。整个装置具有小型便携化、应用简便、可展示性和可扩展性好等特点。     

带有RCC的异步风力发电机系统的特性分析

介绍了带有转子电流控制器（RCC）的变桨距调节异步风力发电机系统的基本原理及其控制策略。基于Saber仿真软件，建立了变桨距风力机、绕线式异步发电饥、转子电流控制器以及风速等的仿真模型，并以此为基础深入研究了该类风力发电机系统的运行特性。仿真分析表明，引入转子电流控制可以明显改善发电机的输出电能品质，降低变桨距风力机的调节频率，延长变桨距机构的使用寿命。制作了一套7．5kW模拟异步风力发电机的RCC系统，对带有RCC的异步风力发电机系统进行了模拟实验研究。     

太阳能热风发电技术及其应用

在太阳能热气流发电的基础上增设进风口,形成了利用太阳能和风能的太阳能热风发电系统。建立了太阳能热风发电热动力稳态数学模型,通过此模型可判断出发电系统的稳定性,并可解出热风风速、集热棚出口温度及稳态数学模型的其它参数。文章介绍了太阳能热风发电系统的实际运行情况,运行结果与数学模型计算结果相吻合。理论分析和运行实践表明,提高塔筒高度、加大塔筒内外温差、增加集热棚的太阳能吸收率、增大集热棚面积系数及风力发电机组的风能利用率,是提高太阳能热风发电量的途径。     

用于槽式太阳能光热发电过热一体式蒸汽发生器的概念设计

文章提出了一种兼具过热段可用于槽式太阳能光热发电系统蒸汽发生器的概念机型．介绍了它的功能及运行原理。针对光热发电系统的特点对其主体结构进行了设计,使之能够适应大温差、变负荷的运行工况。从经济性和安全性的角度出发,对其运行方案及控制方案进行了分析。     

基于分级模糊控制风力太阳能混合发电控制系统的研究

针对分散式风力太阳能混合发电系统的特点,提出了基于分级模糊控制器的风力太阳能混合发电能量管理控制方法,设计了一四级分级模糊控制器来实现对系统的能量管理和控制;并对所设计的能量管理系统进行了仿真研究,仿真结果表明所设计的控制器具有良好的控制性能,证明此方案是可行的。     

离网型混合发电系统的分布式预测控制

针对离网型风力发电和光伏发电构成的混合发电系统,研究其功率的优化分配问题,提出采用分布式预测控制的分层控制结构。应用迭代分布式MPC(model predictive control)优化算法,分别设计风力/光伏发电子系统的MPC优化问题,通过MPC之间的信息交换,得到保证全局性能优化的风力/光伏发电子系统的功率参考值,根据此功率参考值,本地控制器调节风力/光伏发电子系统的运行状态,达到混合发电系统的全局优化运行,可解决混合发电系统中集中式MPC优化模型复杂、难以满足实时控制要求的问题。仿真结果表明,采用迭代分布式MPC的离网型混合发电系统,能够很好地满足负荷的功率需求,并延长蓄电池的使用寿命。与集中式MPC相比,迭代分布式MPC能够在保证较小性能指标的前提下,减小优化问题的计算复杂度。     

太阳能风力和柴油机混合发电系统

据《远东技术评论》报道,一种以太阳能、风力和柴油机为动力的混合发电系统已由英国霍克·西德利发电厂试制成功。这种供电系统利用自然的风力和太阳能,同时与一台构成一个备用发电系统的柴油发电机相连。其主要用途是为无     

液压型风力发电机组最优功率追踪控制方法研究

为研究风力发电机组风能利用率,对液压型风力发电机组的风力机特性和液压主传动闭式系统进行建模分析,提出一种变步长的最优功率追踪控制方法.该方法根据风力机角速度和发电功率判断风力机运行区间,依据不同的运行区间对给定功率进行实时调整,通过控制发电功率间接控制风力机角速度,实现最优功率追踪控制.基于30kVA液压型风力发电机组实验平台进行仿真和实验研究.结果表明:采用变步长最优功率追踪控制方法,系统压力和发电功率可准确地跟踪风速变化,该方法具有良好的控制效果.     

太阳能烟囱制冷系统的研究

通过分析制冷系统和太阳能烟囱热气流发电系统的技术和特点,提出了太阳能烟囱制冷系统.将太阳能烟囱系统与制冷系统相结合进行制冷,可实现制冷不用电.该系统由烟囱、集热棚、蓄热层、涡轮机、开启式制冷压缩机、冷凝器和变速器等组成.介绍了太阳能烟囱制冷系统的结构特点、工作原理以及系统相关参数的计算方法.分析结果表明,太阳能烟囱制冷系统结构简单,运行维护方便,制冷不用电,无污染,具有良好的环境效应,可根据环境温度改变压缩机运行转速调节供冷负荷,能有效解决热带及沙漠地区的供冷及供电问题.     

基于WINDOWS的微型燃气轮机实时智能监控系统

微型燃气轮机是一种新型的低排放的分布式发电装置，可广泛应用于分布式电站、冷热电联产以及混合电动汽车等领域。为对微型燃气轮机和动力电池组合进行混合动力应用试验研究，将微型燃气轮机与油耗仪、外接电池组和负载组成试验系统，通过控制发电机功率的数字功率控制器的用户维护串口，在Windows环境下开发监控程序，对微型燃气轮机运行状态参数，进行自动实时监控，并对发电功率进行自动调节。     

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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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.     

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.