内河船舶LNG发动机-蓄电池混合动力系统性能仿真

为改善船舶天然气发动机动力系统调速性能,提高内河液化天然气（LNG）燃料动力船舶的操纵性及安全性,提出构建天然气发动机-蓄电池混合动力系统。分别针对LNG发动机动力系统及混合动力系统建立Matlab/Simulink仿真模型,并实现了船舶起动和变负荷过程。对两种仿真系统的仿真结果进行分析,结果表明：采用该混合动力系统的船舶变负荷过程航速变化区间变大,系统达到稳定时间缩短;采用设计的控制策略,天然气的消耗最多降低19.6%;NOx、CO、HC排放分别最多降低22.1%、18.5%、23.6%。     

内河船舶液化天然气发动机-蓄电池混合动力系统性能仿真

为改善船舶天然气发动机动力系统调速性能,提高内河液化天然气(LNG)燃料动力船舶的操纵性及安全性,提出构建天然气发动机-蓄电池混合动力系统。分别针对LNG发动机动力系统及混合动力系统建立Matlab/Simulink仿真模型,并实现了船舶起动和变负荷过程。对两种仿真系统的仿真结果进行分析,结果表明:采用该混合动力系统的船舶变负荷过程航速变化区间变大,系统达到稳定时间缩短;采用设计的控制策略,天然气的消耗最多降低19.6%;NO_x、CO、HC排放分别最多降低22.1%、18.5%、23.6%。     

电站甩负荷情况下动力系统的协调控制策略研究

针对电站甩负荷时,主蒸汽压力易产生超压,且传统PID控制器无法快速有效地控制主蒸汽压力的问题,设计了燃烧系统和主机回汽协调控制策略以及小脑神经网络(Cerebellar Model Articulation Controller,CMAC)与PID并行的控制器,并在Simulink平台上进行了电站甩30%和100%负荷时系统动态特性仿真。结果表明:所设计的控制策略和控制器能够使主蒸汽压力控制系统较快地对电站的大负荷扰动作出响应,取得较好的控制效果,保障动力系统的稳定。     

柴电混合动力系统电力推进模式下离合器柔性接排启动轴系过程仿真研究

以某公务船柴电混合动力系统为研究对象,利用AMESim软件建立动力系统仿真模型,开展电力推进模式中轴系接排启动过程的仿真研究。仿真分析了采用柔性接排技术后,轴带电机在齿轮箱离合器高速接排启动轴系过程中所受冲击的大小变化,并和试验数据进行比较。结果表明:柔性接排可有效降低接排过程中轴带电机所受的冲击,保证系统可靠运行;仿真模型动态精度大于90%,仿真模型有效。     

某型混合动力系统大功率轴带电机平稳启动并网的控制方法及实船应用

在双机双桨混合动力系统的并车推进/电机推进模式切换过程中,采用小电机辅助启动控制方法与主机辅助启动控制方法可实现大功率轴带电机平稳启动并网控制,避免其直接启动并网造成大电流危害船舶电网等问题。经实船验证,小电机辅助启动控制方法与主机辅助启动控制方法可靠且有效,在轴带电机启动过程中能够保障船舶安全航行,同时降低动力系统设备成本、节省船舶安装空间。     

基于定距舵桨的柴电混合港作拖轮动力系统设计

针对某型常规港作拖轮89%工作时间主机工作在30%以下的低负荷工况,导致排放差、油耗高的问题,基于该船定距舵桨条件,开展柴电混合动力推进系统的设计。经过船模试验的航速和拖力预报显示:所设计的动力系统满足技术要求。基于定距舵桨的柴电混合动力系统设计方法可为拖轮及拖网渔船等具有自航和拖带两种工况的船舶的动力系统设计提供借鉴。     

飞轮储能在钻机动力调峰中的应用研究

石油钻机起下钻工况中的载荷呈现脉冲波动特性,为了应对短时冲击负荷,有必要引入飞轮储能调峰运行技术,以平抑发动机的功率突增,减少动力热备容量,达到节能减排的目的。提出一种基于飞轮储能的混合动力传动系统,飞轮储能系统储存辅助发电机的小功率电能、下钻工况中的势能回收电能,大功率释放电能供给调峰电机。飞轮储能系统与绞车下钻势能回收系统、辅助发电系统、调峰电机系统组网联合调试,在卫453井示范工程中进行调峰试验、液力耦合器配置试验、能量回收功能试验、调峰电机系统电气总控试验。试验结果表明,飞轮储能动力调峰系统能够快速响应载荷的变化,将柴油机在响应冲击负荷时的功率突增减少40%~58%。柴油机与链条并车箱之间的液力耦合器可以用传动效率更高的齿轮变速器替代,无液力耦合器的混合动力系统油耗可降低10%以上。     

中央空调冷却水系统变频节能技术改造

根据一年中气温变化较大,制冷主机冷负荷变化较大,水系统大部分时间在大流量、小温差状态下运行的特点,将冷却水系统与变频器有机结合,形成环状系统,通过空调负荷的变化而改变电源频率,达到通过调节电机转速自动控制冷却水流量的目的。这样,既提高了水泵电机输出效率,又在满足制冷主机对冷却水流量要求的同时,降低了水泵电机轴功率,减少了电能消耗。     

柴电混合动力船舶机动性能研究

为解决传统机械推进系统在低速机动航行阶段出现油耗率高及环境污染严重等问题,结合柴油机驱动与电机驱动各自的优点,运用Matlab/Simulink分别建立四象限船-机-桨运动模型及柴油机、电机动力系统的动态仿真模型,对比分析低负荷机动航行工况下纯柴油机驱动船舶速度响应与电机驱动船舶速度响应及油耗量与耗电量情况。研究结果表明,低速机动航行起动工况下电动机驱动(power take in,PTI)模式具有经济、节能环保和动力性良好的优势,该研究为船舶混合动力系统的研究提供了理论支撑及指导。     

船舶柴电混合动力系统在电力助推模式下的性能仿真研究

应用AMESim软件对船舶柴电混合动力系统建模并进行试验验证。试验验证表明:所建立的模型稳态误差≤5%,满足精度要求。采用所建立的模型仿真分析了Booster模式下系统在不同工况下的匹配特性;并研究了柴油机与轴带电机稳定运行的控制策略。     

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.     

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。     

Contents in Volume 23,2014

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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.