2205双相不锈钢硅铝复合脱氧的实验研究

在实验室进行了不同加铝量的2205双相不锈钢硅铝复合脱氧及钙处理的热模拟实验,研究了钢中铝含量对总氧含量和脱氧产物的影响。结果表明:在一定的加铝范围内,加入的铝粒越多,钢中酸溶铝Al S含量越高,最终的氧含量越低。未加铝粒的实验组中,脱氧阶段夹杂物类型为SiO_2-Al_2O_3-MnO和SiO_2-Al_2O_3-MnO-MgO。加入铝粒的实验组中,钢中w(Al_S)0.005 4%,脱氧阶段夹杂物为SiO_2-Al_2O_3-MnO和MgO-Al_2O_3,加入铝含量越多,SiO_2-Al_2O_3-MnO夹杂物成分中Al_2O_3的含量越多;w(Al_S)≥0.005 4%,脱氧阶段夹杂物只有MgO-Al_2O_3。当w(Al S)≤0.005 4%,钙处理后的夹杂物为CaO-SiO_2-Al_2O_3-MgO,加入铝量越多,夹杂物成分中Al_2O_3的含量越多;w(Al_S)=0.016%时,钙处理后的夹杂物为CaO-Al_2O_3-MgO。     

电弧炉出钢过程在线喷粉Al-C复合脱氧研究及应用

为了降低合金脱氧剂的消耗，提高钢液纯净度，对电弧炉出钢过程在线喷粉Al-C复合脱氧技术进行研究。对Al-C复合脱氧反应进行了热力学理论研究，并设计试验方案验证该技术的应用效果及影响因素。试验结果表明：在Al投入钢液中开始进行脱氧反应时，Al完全起主导作用，先于钢液中C参与脱氧反应；随着钢液中C浓度的升高，Al的溶解度呈明显下降趋势；在应用炉后喷粉的工艺后所需的Al合金的投入量明显减少。在某钢厂初步应用该技术，发现确实可以降低脱氧剂的消耗，提高钢种洁净度。     

开式简单布雷顿制冷循环热力学优化 2.性能优化

为对开式简单布雷顿制冷循环的热力学性能进行优化,根据本文第一部分建立的热力学模型,采用数值计算的方法,分别给出了空气制冷循环制冷率分析和优化结果,在输入功率、装置总的流通面积和总的热导率约束条件下制冷系数分析和优化的数值计算结果。研究结果表明,存在最佳的压缩机入口压降使制冷循环时的制冷率最大;当给定循环输入功率和装置总尺寸时,存在压缩机最佳入口压降使制冷循环时的制冷系数(制冷率)最大,存在最佳的高低温侧换热器热导率分配使制冷系数最大;最大制冷系数(制冷率)对压缩机压比有最大值。     

中碳高钛合金钢水口结瘤形成机理的研究

针对中碳高钛合金钢钢水浇注过程中形成的水口结瘤物进行了机理研究和控制方法分析。扫描电镜检测结果显示,结瘤物主要是由Ti Ox-Al2O3-Mg O矿相组成,部分结瘤物掺杂Ti N以及冷铁等物质。利用热力学软件FACTSAGE进行计算,结果表明1 823 K下,将中碳高钛合金钢钢水中w(Al)降低到48×10-6以下或升高w(Ti)至620×10-6以上,可将镁铝尖晶石变性为液态的Ti Ox-Al2O3-Mg O夹杂物,从而提高钢水可浇性。     

铝钛脱氧钢中夹杂物特征及水口结瘤问题分析

含钛微合金钢普遍存在钢水可浇性不高,水口易堵塞的问题.综述了国内外铝钛镇静钢的发展和研究现状,分析了铝钛镇静钢脱氧特征,总结了不同脱氧工艺和钢水二次氧化对钢中夹杂物特征的影响,并重点分析了铝钛镇静钢水口结瘤成因及预防措施,以期为提高铝钛镇静钢钢水可浇性和产品质量提供借鉴作用.     

喷射器性能及太阳能喷射制冷系统工质的优化

考虑实际流体热力学性质、混合效率和激波等因素,建立了喷射器热力学模型,计算结果与文献中实验数据吻合很好。文中计算了采用环境友好工质R134a、R152a、R717、R290、R600a时喷射系数及喷射制冷系统性能系数。结果表明,对于确定几何参数的喷射器,喷射系数和喷射制冷系统性能系数主要取决于膨胀比与压缩比,两者分别随膨胀比的增加而增大,压缩比的增加而减小。太阳能驱动喷射制冷系统时(发生温度在80℃左右),采用R134a可以使喷射系数和喷射制冷系统能效比最大,明显优于其他工质。     

复叠式制冷系统中的分析

一、引言 对制冷循环经济性的评价习惯上常采用制冷系数来表示,即ε=Q_0/w(Q_0代表制冷量,w代表制冷过程中消耗的功)。但它和其它热力学经济指标,如热机的效率、热泵的供热系数、设备的传热效率等一样,建立在热力学第一定律基础之上,只反映出能量在“数量”方面被利用的程度而不能直接反映出能量在“品质”方面的变化程度。而且这些热力经济指标可大于1(制冷系数)、     

热再生氨化学电池的实验研究及热力学分析

热再生化学电池是一种利用低品位热能的新型途径,其中,热再生氨化学电池(TRAB)具有能量密度高的优势。为了提高电池容量,本文对电解液含0.1~3.5 mol/L Cu(NO_3)_2的TRAB进行了实验与理论研究。在常压、293.15~323.15 K温度范围内,实验测得TRAB阳极对Cu(NH_3)_4~(2+)/Cu的温度系数为-0.879 mV/K,与理论计算值相差6.14%。进而对一个TRAB基本循环进行热力学分析,研究TRAB工作温度和再生温度的影响。当TRAB工作温度从293.15 K升至323.15 K时,放电效率从50.77%提高至54.91%;当再生温度为373.09 K、环境温度为303.15 K时,发电效率为0.49%,相应的循环热力学完善度为5.51%。     

丁烯/丁醇异构体低温氧化Waddington反应机制理论研究

Waddington机理是烯烃和醇类异构体低温氧化机理建模的重要组成部分．针对丁烯/丁醇异构体,系统研究了低温氧化过程的Waddington动力学机制．基于量子化学原理,对该反应机制下的反应速率常数和物种热力学性质进行计算．基于过渡态理论,结合RRKM/ME方法,获得目标体系温度-/压力依赖的速率系数．在统计热力学的基础上,计算了所有关键物种温度相关的内能、生成焓、熵和热容等热力学量．与文献结果比较发现,异丁烯(R4和R5体系)的动力学与热力学参数均与文献值吻合较好．该理论计算结果可直接用于丁烯和丁醇异构体低温氧化动力学模型构建．     

基于CFD数值模拟下的蒸汽喷射器性能预测

建立了蒸汽喷射器热力学模型,并验证了该模型性能及结构计算的可靠性。并针对实际情况中,对该模型进行了动态模拟。结果显示：当工作流体的温度升高时,工质流体的质量流量都会增加,引射系数存在峰值,峰值所对应温度为热力学模型设定温度值;当引射流体的温度升高时,其质量流量也会随之增大,而工作流体的质量流量则较稳定,因此引射流体温度与压力的升高可以改善喷射器的性能;当背压升高时,在一定压力范围内,工质流体的质量流量都趋于稳定,而当背压超过热力学模型设定背压值时,引射流体的质量流量便随背压的升高而急剧下降,喷射器性能严重恶化,故认为该压力值为喷射器的临界背压。本文研究结果对喷射器的设计计算具有一定的指导作用。 关键词：蒸汽喷射器;热力学模型;数值模拟;引射系数     

合成渣在电炉冶炼SPCC出钢过程中的应用

介绍了采用新型合成渣的改进工艺以后,电炉实现了SPCC钢的规模化生产,克服了铝镇静钢在电炉生产线中存在的脱硫困难、精炼炉冶炼时间过长、钢水吸气增氮、钢水中铝夹杂物含量超标、铸坯质量下降和浇铸过程中的结瘤现象,供同行参考.     

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。