Fuel recycling feedback control via real-time boron powder injection in EAST with full metal wall

A feedback control of fuel recycling via real-time boron powder injection,addressing the issue of continuously increasing recycling in long-pulse plasma discharges,has been successfully developed and implemented on EAST tokamak.The feedback control system includes four main parts:the impurity powder dropper(IPD),a diagnostic system measuring fuel recycling level represented by D_(α)emission,a plasma control system(PCS)implementing the Proportional Integral Derivative(PID)algorithm,and a signal converter connecting the IPD and PCS.Based on this control system,both active control and feedback control experiments have recently been performed on EAST with a full metal wall.The experimental results show that the fuel recycling can be gradually reduced to lower level as PCS control voltage increases.In the feedback control experiments,it is also observed that the D_(α)emission is reduced to the level below the target D_(α)value by adjusting boron injection flow rate,indicating successful implementation of the fuel recycling feedback control on EAST.This technique provides a new method for fuel recycling control of long pulse and high parameter plasma operations in future fusion devices.

Effect of metal powders on explosion of fuel-air explosives with delayed secondary igniters

In order to improve the energy level of fuel air explosive(FAE) with delayed secondary igniters, high energetic metal powders were added to liquid fuels mainly composed of ether and isopropyl nitrate.Metal powders’ explosive properties and reaction mechanisms in FAE were studied by high-speed video,pressure test system, and infrared thermal imager. The results show that compared with pure liquid fuels, the shock wave overpressure, maximum surface fireball temperature and high temperature duration of the mixture were significantly increased after adding high energetic metal powder. The overpressure values of the liquid-solid mixture at all measuring points were higher than that of the pure liquid fuels. And the maximum temperature of the fireball was up to 1700C, which was higher than that of the pure liquid fuels. After replacing 30% of aluminum powder with boron or magnesium hydride, the shock wave pressure of the mixture was further increased. The high heat of combustion of boron and the hydrogen released by magnesium hydride could effectively increase the blast effect of the mixture. The improvement of the explosion performance of boron was better than magnesium hydride. It shows that adding high energetic metal powder to liquid fuels can effectively improve the explosion performance of FAE.

In situ grown nanoscale platinum on carbon powder as catalyst layer in proton exchange membrane fuel cells(PEMFCs)

An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode （GCE） to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic （IV） acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm （diameter） x l0 nm （length） by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry （CV） and scanning electron microscope （SEM） as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants （oxygen or hydrogen）.

Synthesis of La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3-δ) Powder for Solid Oxide Fuel Cell by a Nitrate-Citrate Combustion Route

A nitrate-citrate combustion route to synthesize La0.9Sr0.1Ga0.8Mg0.2O3-σ powder for solid oxide fuel cell application was presented. This route is based on the gelling of nitrate solutions by the addition of citric acid and ammonium hydroxide, followed by an intense combustion process due to an exothermic redox reaction between nitrate and citrate ions. The optimum technical parameters are that the pH value is 5, and the molar ratio of citric acid to the total metallic ion is 1.5:1. X-ray diffraction characterization of calcined gel shows that pure phase was synthesized after calcination at 1400℃for 10 h, and the TEM result shovvs the calcined powder with average particle size is about 150 nm. The grain resistance contributes to the total resistance of sintered peliet below 500℃. The conductivity of the sintered peliet at 800℃ was 0.07 S-1·cm-1 higher than the conductivity of YSZ (0.05 S-1·cm-1 at 800℃)

A Steam-Plasma Igniter for Aluminum Powder Combustion

High-temperature ignition is essential for the ignition and combustion of energetic metal fuels, including aluminum and magnesium particles which are protected by their high- melting-temperature oxides. A plasma torch characterized by an ultrahigh-temperature plasma plume fulfills such high-temperature ignition conditions. A new steam plasma igniter is designed and successfully validated by aluminum power ignition and combustion tests. The steam plasma rapidly stabilizes in both plasma and steam jet modes. Parametric investigation of the steam plasma jet is conducted in terms of arc strength. A high-speed camera and an oscilloscope method visualize the discharge characteristics, and optical emission spectroscopy measures the thermochemical properties of the plasma jet. The diatomic molecule OH fitting method, the Boltzmann plot method, and short exposure capturing with an intensified charge coupled device record the axial distributions of the rotational gas temperature, excitation temperature, and OH radical distribution, respectively. The excitation temperature at the nozzle tip is near 5500 K, and the gas temperature is 5400 K.

Single-step Preparation of Nano-homogeneous NiO/YSZ Composite Anode for Solid Oxide Fuel Cells

Homogeneous co-precipitation and hydrothermal treatment were used to prepare nano- and highly dispersed Ni O/YSZ(yttria-stabilized zirconia) composite powders. Composite powders of size less than 100 nm were successfully prepared. This process did not require separate sintering of the YSZ and Ni O to be used as the raw materials for solid oxide fuel cells. The performance of a cell fabricated using the new powders(max.power density ~0.87 W/cm^2) was higher than that of a cell fabricated using conventional powders(max. power density ~0.73 W/cm^2). Co-precipitation and hydrothermal treatment proved to be very effective processes for reducing cell production costs as well as improving cell performance.

The impact of NiO on microstructure and electrical property of solid oxide fuel cell anode

Ni-Ce0.8Sm.2O.9 （Ni-SDC） cermet was selected as anode material for reduced temperature （800℃） solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electrode performance was investigated so that the result obtained can be applied to make high-quality anode. Three kinds of NiO powder were synthesized with a fourth kind being available in the market. Four types of anode precursors were fabricated with these NiO powders and Ce0.8Sm.2O.9 （SDC）, and then were reduced to anode wafers for sequencing measurement. The electrical conductivity of the anodes was measured and the effect ofmicrostructure was investigated. It was found that the anode electrical conductivity depends strongly on the NiO powder morphologies, microstructure of the cermet anode and particle sizes, which are decided by NiO powder preparation technique. The highest electrical conductivity is obtained for anode cermets with NiO powder synthesized by NiCO3-2Ni（OH）2-4H2O or Ni（NO3）2-6H2O decomposition technique.

高燃烧效率含卤氧化剂包覆硼粉的制备及性能

为了提升硼粉的点火燃烧性能,采用高能球磨与喷雾干燥相结合的技术制备了4种微纳米B-Fe-Bi_(2)O_(3)@AP/PVDF复合物,根据其高热值和高燃烧效率的特点将四种复合物命名为μBHH_(c)、μBHC_(e)、nBHH_(c)及nBHC_(e),并对其形貌结构、热反应性、点火延迟、质量燃速和凝聚相产物进行了表征分析。结果表明,μBHH_(c)和μBHC_(e)复合物在氩气中最大热值达9.7 k J·g^(-1),最高燃烧效率达66.2%;在氧气中最大热值达14.6 k J·g^(-1),最高燃烧效率达93.3%,空气中氧化峰温在750~760℃之间。n BHH_(c)和n BHC_(e)复合物在氩气中最大热值达9.9 k J·g^(-1),最高燃烧效率达68.9%;在氧气中最大热值达14.8 k J·g^(-1),最高燃烧效率达97.2%,空气中氧化峰温在595~600℃之间。各类复合物的最高燃烧温度达1954~2011℃,其中n BHH_(c)复合物的点火延迟最短(26 ms),且质量燃速最高(1.84 g·s^(-1));μBHC_(e)复合物的点火延迟最长(39 ms),质量燃速也最低(0.80 g·s^(-1))。各类复合物燃烧产物主要由B_(2)O_(3)、B_(4)C及少量未完全燃烧的硼组成,形貌包含5~10μm的球体及10~20μm的片状物质。

旋转爆轰发动机内煤粉-氢气两相爆轰流场数值研究

旋转爆轰发动机因其较高的热循环效率在航空航天领域备受关注。为了研究气固混合燃料在空气氛围中的旋转爆轰特性,在圆柱坐标系中建立了气固混合相燃料爆轰理论模型,并基于三维守恒元与求解元方法,对圆盘形燃烧室内的爆轰过程进行三维数值模拟。计算获得了气固混合相旋转爆轰波稳定传播时的流场结构,分析了爆轰流场的热力学参数分布特征、化学反应区分布以及旋转爆轰波后的波系分布特点。研究结果表明,微米级煤粉在氢气辅助作用下可快速反应并支持旋转爆轰波的稳定传播,但因盘形燃烧室的扁平结构特征和非预混喷注方式,导致爆轰波波阵面呈现为不规则的曲面。煤粉和氢气射流穿透空气层的能力差异导致气固混合燃料的化学反应区发生分离,最终以双反应区的爆轰组织形式支持旋转爆轰波稳定传播。旋转爆轰波不规则的曲面结构使其在扁平的燃烧室中发生多次反射,进而在爆轰波后有规律地出现多道反射激波。

典型金属粉末对FAE冲击波效应和热毁伤性能的影响

为了探究典型金属粉末对燃料空气炸药(fuel air explosive,FAE)冲击波效应和热毁伤性能的影响,采用20 L球形液体爆炸测试系统并结合比色测温方法,深入研究了不同金属粉种类和含量下环氧丙烷(epoxypropane,PO)的燃爆特性、火焰结构及温度分布特征。实验结果表明:纯环氧丙烷的最佳质量浓度为780 g/m^(3),最大爆燃超压Δp_(max)=0.799 MPa,最大压力上升速率(dp/dt)_(max)=52.438 MPa/s。添加Al粉、Ti粉和Mg粉的环氧丙烷最大燃爆超压、最大压力上升速率和最大火焰平均温度均随着金属粉末质量比(I)的增加而增大,而最大压力上升时间的变化趋势则与之相反;最大燃爆超压和最大火焰平均温度的变化规律一致,从大到小依次为:Al/PO、Mg/PO、Ti/PO,且当金属粉的质量比I=40%时,3种固-液混合燃料的?pmax值相较于纯环氧丙烷分别增加了12.00%、8.41%和11.54%;此外,最大压力上升速率和燃烧速率的变化规律一致,从大到小依次为:Mg/PO、Al/PO、Ti/PO,且当金属粉的质量比I=40%时,3种固-液混合燃料的(dp/dt)max值相较于纯环氧丙烷分别增加了41.91%、39.60%和45.29%。研究结果表明,不同高能金属粉末在改善环氧丙烷燃爆性能方面各有优势,在FAE的配方设计时,应根据毁伤性能指标合理选择金属粉末作为含能添加剂。

气固两相粉末燃料爆轰及其推进应用研究进展

粉末燃料因其能量密度高、稳定性好等优势,作为爆轰推进动力系统的燃料或添加剂,具有广阔的应用前景。根据气固两相粉末爆轰的燃料种类进行分类,并以指导粉末爆轰推进技术应用为导向,回顾粉末燃料在氧化剂氛围以及气体燃料/氧化剂氛围中起爆特性和传播特性的国内外研究进展,并对二者进行理论和工程技术的研究归纳,概括影响气固两相爆轰起爆和传播特性的因素以及重要的研究结论。从应用前景、推进性能、难点与挑战等角度对两相爆轰发动机研究进行综述,在总结发动机数值和实验研究现状的基础上,对未来需要开展的研究工作进行展望。

粉末燃料典型流化装置流量调节对流化的影响

粉末燃料供应系统是实现粉末冲压发动机流量调节的最关键技术,供应系统的优劣直接影响发动机性能,也是需要解决的主要问题之一。本文运用欧拉连续介质方法对粉末燃料典型流化装置流量调节对流化的影响进行研究,探究流量调节过程中等固气比调节对流化的影响,分析粉末在存储罐、流化区域、出口管路上的分布规律。通过分析等固气比调节的输出粉末质量流量变化规律、粉末分布、罐体气相压降判断粉末流化效果的优劣,进而完成粉末燃料典型流化装置流量调节对流化影响的研究。结果表明,随着输入粉末质量流量的增大,粉末供应到达稳定供应状态的时长逐渐减小;输入粉末平均质量流通量在12732.4~16976.5 kg/(m2·s)的设计工况,到达稳定供应状态需要的时间短,是较为理想的输入粉末质量流量的设计工况;粉末燃料供应系统为欠阻尼系统,供应系统开机后推力增加的过程中,阻尼振荡频率随着输出粉末质量流量的增大而增大;在到达稳定前,流化区域形成的旋流影响范围先增大再变小后保持稳定(或者消失),旋流具有稳定粉末供应的作用。

燃料燃烧特性及其对烧结烟气CO排放的影响

本文采用热重分析试验开展焦粉和洗精末的燃烧特性分析,随后通过烧结杯试验探究不同燃料结构和粒度分布下燃料的燃烧行为对烧结烟气中CO排放的影响,从烧结CO生成机理分析出发,深入解析了固体燃料在热解和燃烧过程中固体碳的反应机制,阐述了烧结燃料结构与粒度分布变化导致料层内部温度及氧势变化对燃料燃烧产生CO的不同影响。结果表明,随着洗精末比例的逐渐提高,烟气中CO体积分数逐渐上升,尤其在洗精末配比超过50%后,CO体积分数由2.12%显著上升到2.60%,燃料粒级分布改善后烟气中的CO体积分数有较明显的下降,降幅约为39.5%。因此,适当的增加烧结燃料中洗精末的配比再配合燃料粒度的提高可以有效降低烧结烟气中CO的排放。

微波辅助Al@PVDF⁃OH复合燃料的制备及其燃烧性能

聚偏氟乙烯(PVDF)等氟聚物可有效抑制铝粉的团聚并提高铝粉的反应活性。但氟聚物与被氧化铝覆盖的Al颗粒表面之间亲和性较差,氟聚物直接包覆在Al表面对团聚的抑制效果并不理想。为增强氟聚物与铝粉间的相互作用,改善铝粉燃烧性能,研究采用微波辅助反应的方法得到了羟基化改性的PVDF-OH,利用溶剂/非溶剂法将PVDF-OH包覆在铝粉表面得到了Al@PVDF-OH复合燃料,并进一步制备了复合固体推进剂。采用红外光谱、X射线衍射仪对PVDF-OH的分子结构与元素组成进行了研究;采用扫描电子显微镜、差示扫描量热仪、高速摄像机和氧弹量热仪等设备对Al@PVDF-OH复合燃料的微观结构组成及其燃烧性能进行了研究。结果表明,微波辅助制备得到的PVDF-OH有着较高的羟基含量,微波功率240 W下处理1 min时制备得到的PVDF-OH最佳。Al@PVDF-OH复合燃料的燃烧性能优于包覆PVDF的Al@PVDF复合燃料与加热改性处理PVDF-OH(H)的Al@PVDF-OH(H)复合燃料,在PVDF-OH含量为15%时最佳。与纯Al相比,PVDF-OH含量为15%的Al@PVDF-OH复合燃料的燃烧热值由19140 kJ·kg^(-1)增加到24912 kJ·kg^(-1);与AP混合后的燃烧测试结果表明,Al@PVDF-OH复合燃料燃烧性能相较于Al有明显改善,点火延迟时间由77 ms缩短至70 ms,燃速由195.7 mm·s^(-1)提高到225.7 mm·s^(-1)。基于Al@PVDF-OH复合燃料的固体推进剂与铝基固体推进剂相比,其燃烧热值由13281 kJ·kg^(-1)增加到14020 kJ·kg^(-1);燃速由1.281 mm·s^(-1)提高到1.915 mm·s^(-1),凝聚相燃烧产物D90由74.324μm降至52.749μm。

Effects of the nozzle structure and fluidized gas composition on the gas-particle two-phase jet characteristic in a powder fuel scramjet

The interaction between nozzle design and fluidization gas composition significantly influences the dynamics within a powder fuel scramjet's combustion chamber.To investigate this relationship,an experimental study utilized high-speed shadow imaging technology to explore the macroscopic aspects of powder fuel injection.The investigation examined various convergence angles,nozzle throat lengths,and fluidized gas compositions.Key findings include:During jet development,powder fuel initially concentrates near the axis,with non-convergence angle nozzles exhibiting longer concentrated distribution periods than convergence angle conditions.Decreasing nozzle convergence angles lead to increased penetration distance,frontal velocity,and radial diffusion distance during the initial stages of jet development.Additionally,stable jet shapes show larger divergence angles as nozzle convergence angle decreases,with the largest divergence angle observed atα=60°.In the initial 0-7 ms of jet development,the powder fuel jet demonstrates greater penetration distance and frontal velocity under certain conditions.Moreover,penetration distance and frontal velocity increase with throat length from 7 to 20 ms,accompanied by changes in divergence angles.Specifically,at a throat length(l)of 2 mm,the near-field divergence angle measures 46.50°,and the far-field divergence angle is 22.25°.Conversely,at l=8mm,the near-field divergence angle is 33.49°,and the far-field divergence angle is 23.21°.The fluidization gas composition minimally affects jet penetration distance and frontal velocity during the initial 0-3 ms.However,due to hydrogen's low density,hydrogen/powder fuel jets exhibit shorter distances and velocities compared to nitrogen/powder fuel jets.Hydrogen fluidization also results in larger divergence angles,particularly in the near field.These findings underscore the importance of nozzle design and fluidization gas composition in optimizing scramjet performance and efficiency.

首钢股份焦粉粒级优化实践

为提高烧结矿产量和质量、优化烧结机参数,采用对辊+四辊破碎工艺替代原有对辊破碎工艺。通过一系列工艺改进措施,焦粉粒级+5 mm含量由20.16%降至9.45%,-3 mm粒级含量由62.98%增加至70.64%;烧结机参数得到优化,其中终点温度降低17.13℃,总管温度降低9.15℃;烧结矿产量提高140 t/d,转鼓强度提高1.24%,平均粒径提高0.45 mm,-10 mm粒级含量降低1.02%,燃耗降低0.72kg/t。

不同粒度级配的硼基粉末燃料装填特性和流动性

为了阐明粒度级配对粉末燃料装填特性和流动性的影响规律,提高粉末冲压发动机工作性能,以硼基粉末燃料为对象,研究了颗粒物性和级配方式等对粉末燃料装填特性和流动性的影响,并利用粉末供给系统验证了级配粉末的流化输运性能。结果表明,大粒径颗粒间隙中填充小粒径颗粒能够提升装填密度,但却会降低其流动性;多级级配粉末中的小粒径颗粒流动性较差时,预混装填方式的级配颗粒装填密度高于分批装填方式,反之则分批装填方式更好;团聚造粒制备的硼基粉末燃料粒度分布均有分形分布特征,分形级配的方式也可以提高颗粒装填密度,提升幅度约15.7%,分形级配后分形维数为2.33,装填密度为0.957g/cm^(3),装填率为53.8%,并保持较好的流化性能。

硼基粉末燃料冲压发动机掺混燃烧特性研究

针对硼基粉末燃料冲压发动机超声速燃烧组织难题,建立气-固两相掺混燃烧方法,开展典型工况(26 km,Ma=6.0)的数值仿真研究,得到了发动机燃烧室内的流动燃烧特性,仿真分析了粉末燃料喷注速度、燃料颗粒粒径以及凹腔结构对燃烧室内气-固两相掺混燃烧情况的影响。结果表明:粉末燃料点火温度是影响燃料掺混燃烧效率的关键因素,当粉末喷注于气相燃烧高温区时,可显著提高燃烧效率;合理的喷注速度有利于增强颗粒与燃气和来流的掺混程度,使得颗粒燃烧更充分;当颗粒粒径从5μm提高至20μm时,射流穿透深度显著增加,粒径5μm时粉末燃烧效率最高,随着粒径增大颗粒点火的难度提高,不利于燃料充分燃烧释热;凹腔结构形成的回流区可以形成较好的点火区域,对于粉末燃料及富燃燃气和超声速来流的掺混起到较好的增益效果,有利于提高燃烧效率。

双硬质相材料Cr_(3)C_(2)-WC-NiCoCrMo热喷涂工艺研究

采用团聚-烧结法制备了双硬质相材料Cr_(3)C_(2)-WC-NiCoCrMo热喷涂粉末,并利用超音速火焰(HVOF)喷涂技术制备了涂层,研究了粉末微观结构和热喷涂氧燃比(λ)对涂层显微组织和性能的影响。结果表明:随着烧结温度升高,喷涂粉末的松装密度和流动性增加,微观结构趋于致密;在热喷涂氧燃比固定为1.09的条件下,当喷涂粉末的烧结温度为1 295℃时,制备的涂层综合性能较好,显微硬度为(1 135.8±40.7)HV_(0.3),孔隙率为1.1%±0.1%;在喷涂粉末的烧结温度固定为1 295℃的条件下,当热喷涂氧燃比为1.0时,制备的涂层综合性能最好,其显微硬度为(1 145.8±39.6)HV_(0.3),沉积效率为48.8%,孔隙率为1.0%±0.1%。

首钢股份高炉喷吹煤粉助燃剂实践探究

21世纪以来,随着高炉喷煤理论技术的不断完善,利用煤粉替代昂贵的高炉冶金焦已是钢铁企业降本增效的重要手段。在当今严峻的经济形势下,首钢股份高炉不断强化创新,寻求技术突破,喷吹煤粉量的提升就是高炉强化带来的结果。首钢股份高炉在大喷煤技术的运用下,率先尝试添加煤粉助燃剂的喷吹试验,旨在改善高炉生产指标,增加煤焦置换比,降低吨铁成本,提高企业竞争力。实际生产试验结果表明,助燃剂中的有效成分能够影响煤粉微观结构,总而言之使煤粉中C原子更易于与O原子结合,促进煤粉燃烧,降低了燃料消耗,最终高炉燃料比降低了6.44 kg,带来了可观的效益。同时,对添加助燃剂前后高炉的一些重要参数变化进行了分析探究。