燃池内的阴燃过程的实验分析研究

为了分析燃池内的燃烧过程,设计制造了水平和竖直的纤维质燃料阴燃实验台,进行了 阴燃过程气体成分的实验分析。实验结果给出了在不同的阴燃阶段ＣＨ４、Ｈ２、ＣＯ和ＣＯ２等 气体的生成规律,以及含水量、空气量和阴燃传播方向等对生成气体的影响,为深入研究阴燃的机 理,提高燃池的用能水平提供了必要的依据。     

清洁及氧修饰Cu（100）表面上水煤气变换反应的能量学

分别以清洁及氧修饰Ｃｕ（１００）表面作为金属态铜和部分氧化态铜的表面模拟，用键级守恒Ｍｏｒｓｅ势法研究了两种表面上水煤气变换（ＷＧＳ）反应的能量学。计算结果表明：清洁Ｃｕ（１００）表面上，ＷＧＳ反应有可能同时按表面氧化还原和甲酸根两种机理进行；表面氧化还原机理中，ＣＯｓ主要由ＯＨｓ（而不是Ｏｓ）氧化为ＣＯ２ｓ。与清洁铜表面相比，Ｃｕ（１００）ｐ（２×２）Ｏ表面上ＷＧＳ反应中活化能最大的基元步骤Ｈ２     

角分辨XPS对自组装单分子层厚度和官能团位置的定性及定量研究

用角分辨ＸＰＳ（Ａｎｇｌｅ－ｒｅｓｏｌｖｅｄＸＰＳ）研究研究了ＨＳ（ＣＨ２）１０ＣＯＯＨ（Ｉ）ＨＳ（ＣＨ２）３ＯＣ６Ｈ４Ｎ＝ＮＣ６Ｈ４（ＣＨ２）７ＣＨ３（ＩＩ）和ＨＳ（ＣＨ２）６ＨＳ（Ⅲ）３种分子在Ａｕ膜表面制备的自组装单分子层，得出了（Ｉ）中Ｓ原子，（Ⅱ）中Ｓ，Ｎ原子距膜表面的垂直距离，并结合构象分析确定了分子的取向和倾角，对分子（Ⅲ）则得出分子在紫外光照射下氧化反应的选择性，发现氧化主要在底层     

利用光谱技术研究硝基甲烷快速反应波传播

本文利用研制的光谱技术，在爆炸激波管中成功地研究了硝基甲烷和氧混合物快速反应波传播的微观特性。光谱测量结果说明：ＯＨ基和Ｈ_２Ｏ、ＮＨ_３的辐射没有发生明显改变，ＣＨ_３Ｏ、ＣＨ、ＮＯ_２、ＣＯ_２、ＮＯ、ＨＣＮ的辐射随反应波传播距离的增加而增长；但是ＣＯ和ＣＨ_２Ｏ的辐射呈倒“Ｕ”型曲线。本文的研究为我国开展含能材料快速反应微观机理的研究探索到一个方法，这种方法投资不大，而且行之有效。     

铝粉对己烷与氧混合物快速反应发射光谱的影响

观察高温激波管中己烷与氧气在不同摩尔比下加入不同粒度铝粉前后的快速反应发射光谱。整个光辐射范围从４００ｎｍ一直延伸到探测上限８３０ｎｍ。对几种较重要反应产物的辐射时间变化进行了研究，发现铝粉的加入提高了己烷的反应特性，确定了几种反应产物光辐射出现的可能顺序为：Ｃ２、ＣＨ、ＣＨ２Ｏ、ＣＨＯ、ＯＨ、Ｈ２Ｏ、ＣＯ２，并对己烷快速反应点火机理进行了初步分析。     

氮气对CH3NO2＋O2快速反应抑制机理的研究

采用激波管技术、光电探测技术及高速数据采集系统研究氮气对ＣＨ３ＮＯ２＋Ｏ２快速反应的抑制作用，通过探测ＣＨ３Ｏ、ＣＨ的辐射强度随氮气加入量的变化关系，分析氮气抑制反应进行的微观机制，得出了氮气抑制ＣＨ３ＮＯ２＋Ｏ２快速反应的主要过程是通过基元反应Ｎ２＋Ｏ→Ｎ２Ｏ消毁掉自由原子Ｏ，从而使自由基ＯＨ、ＣＨ的产量大为减少，支链反应不能继续进行下去，阻碍爆轰反应的实现。     

La—Ce—Mn系钙钛矿型催化剂性能研究

采用共沉淀法制得了Ｃｅ＾４＋，部分取代Ｌａ＾３＋的Ｌａ１－ｘＣｅｘＭｎＯ３钙钛矿型催化剂，实验结果表明，随Ｃｅ＾４＋取代量ｘ的增大，Ｌａ１－ｘＣｅｘＭｎＯ３催化剂越易被还原，其还原活化逐渐降低，对于ＣＯ，ＣＨ４氧化的反应其活性有一最大值，ＣＯ反应ｘ的０．４，ＣＨ４反应ｘ为０．２，这是由于随ｘ值的增大，催化剂晶格缺陷增多，晶格氧的化学势增大，以及ＣｅＯ２杂质相的协同作用的结果，在ＣＯ氧化和用Ｈ２还原     

甲酸乙酯氧化偶联催化剂的表面特征

用ＴＰＳＲ，ＴＰＤ，ＣＴＰＲ和ＩＴＤ在线分析技术，初步考察了ＨＺＳＭ－５负载型金属氧化物催化剂上甲酸乙酯氧化偶联表面反应性能，以及催化剂表面对氧的吸附能力，对ＣＯ吸附和反应性能，同时，通过ＸＰＳ，ＥＰＲ和ＣＯ－ＩＲ，ＣＯ２－ＩＲ等物理方法，对甲酸乙酯氧化偶联催化剂的表面组成，表面酸碱性及在不同温度下ＣＯ和ＣＯ２在催化剂表面吸附态的变化，进行了初步的探索，研究结果初步揭示，不同载体，不同金属氧化组成     

乙烯渣油沥青基活性炭纤维和粘胶基活性炭纤维的表面性质与脱硫活性

研究了在Ｏ２和Ｈ２Ｏ存在下,乙烯渣油肝基活性炭纤维（ＥＴＰ ＡＣＦ）和粘胶基活性炭纤维（Ｃｅｌｌｕｌｏｓｅ ＡＣＦ）的脱硫活性,结果表明,在比表面积相近的情况下,ＥＴＰ ＡＣＦ的脱硫活性明显低于Ｃｅｌｌｕｌｏｓｅ ＡＣＦ,官可归因于后者具有较强的吸附和催化氧化ＳＯ２能力及较大的吸水量,尤其是具有较强的催化氧化Ｓ２的能力,这些能力又珉春表面含有含氮官能团以及某些含氧官能团有关,因此ＡＣＦ的表面官能团     

ZrO2在Rh/γ-Al2O3催化剂中对NO催化还原反应的作用

测定了含ＺｒＯ２的Ｒｈ／γ－Ａｌ２Ｏ３催化剂上ＮＯ＋Ｃ２Ｈ４和ＮＯ＋Ｃ２Ｈ４＋Ｏ２的反应活恬性,并应用ＴＰＲ、ＸＲＤ、ＢＥＴ比表面等表征了ＺｒＯ２的加入方式和晶型对Ｒｈ／γ／Ａｌ２Ｏ３催化剂活性和结构的影响。结果表明,ＺｒＯ２的加入一定程度也抑制了Ｒｈ＾３＋与γ－Ａｌ２Ｏ３之间的相互作用和Ａｌ２Ｏ３的相变,提高了催化剂的热稳定性,明显提高了８５０℃老化样品的ＮＯ＋Ｃ２Ｈ４反应活性。对于ＮＯ＋Ｃ２     

On the mathematical modelling of processes of peat firing and smoldering

Based on a mathematical model of a porous reacting medium the statement and mathematical solution are presented for a problem of the peat smoldering rise as a result of the effect of a lower seat of fire. It is found that at moderate temperatures T ≤ 750 K the firing and smoldering of the initial reagent are determined by the intensity of the external burning seat as well as by the processes of the peat drying, pyrolysis, and the oxidation reaction of the coked fixed bed. The work was financially supported by the Program of the Federal Agency for Education (Grant No. P 042242).     

不同燃烧状态飞火颗粒自由燃烧规律研究

飞火是开放空间中大尺度火灾非连续性蔓延的主要形式。本文通过不同热流下的木质飞火颗粒自由燃烧实验,揭示不同燃烧状态飞火颗粒的结构变形、质量损失及温度分布的变化规律。研究表明,颗粒结构变形受材料化学反应机制和热机械力作用共同影响;颗粒燃烧反应易造成热解气体的内部积聚,以致内压激增、诱发喷射或喷溅细小颗粒的现象;阴燃过程颗粒表面温度变化较小但持续时间很长,明火状态的颗粒持续高温并且温度与质量变化剧烈。     

水雾与可燃多孔介质火焰相互作用的实验研究

采用非传播扩散火焰形式,研究了固体可燃多孔介质中水雾-火焰的相互作用,探讨了床层厚度、多孔介质粒度以及燃料预燃时间对水雾灭火效果的影响。结果表明,随着预燃时间增长,水雾停止后床层内部可能发生闷烧现象,随着燃料粒度的减小,这种闷烧几率反而降低。这表明,固体火焰与水雾的相互作用有其独特之处。     

Mathematical modelling of thermophysical processes at peat firing and smoldering

A new statement and the numerical solution of the problem of the peat layer firing as a result of the effect of the surface fire is given on the basis of a mathematical model of a porous reacting medium. The original reagent smoldering at moderate temperatures (T ₁ ≤ 750 K) is found to be determined by the processes of heat and mass exchange with the forest fire source, peat drying and pyrolysis, reaction of the carbon oxide oxidation, thermophysical characteristics, and the peat height as well as by the thickness of the water layer under the peat layer.     

聚氨酯泡沫反向阴燃的数值模拟

本文根据两步反应机理,建立了2维非稳态燃料阴燃的数学模型.该模型考虑了气体在多孔介质内扩散系数的变化.应用该模型模拟了来流速度对阴燃速度及平均最高温度的影响,结果表明;首先阴燃传播速度随着来流速度的增大而增大,当风速为0.2 cm/s时,阴燃速度达到最大值0.0093 cm/s,而后随着风速的增大阴燃速度逐渐降低直至熄灭;来流速度对阴燃最高温度影响不大.同时还模拟了氧气浓度的影响、燃料阴燃中气体组分和固体成分的变化以及温度分布情况.     

Transition from forward smoldering to flaming in small polyurethane foam samples

Experimental observations are presented of the effect of flow velocity, oxygen concentration, and a thermal radiant flux on the transition from smoldering to flaming in forward smoldering of small samples of polyurethane foam with a gas/solid interface. The experiments are part of a project studying the transition from smoldering to flaming under conditions encountered in spacecraft facilities, i.e., microgravity, low velocity variable oxygen concentration flows. Because the microgravity experiments are planned for the International Space Station, the foam samples had to be limited in size for safety and launch mass reasons. The feasible sample size is too small for smolder to self-propagate because of heat losses to the surroundings. Thus, the smolder propagation and the transition to flaming had to be assisted by reducing heat losses to the surroundings and increasing the oxygen concentration. The experiments are conducted with small parallelepiped samples vertically placed in a wind tunnel. Three of the sample lateral-sides are maintained at elevated temperature, and the fourth side is exposed to an upward flow and a radiant flux. It is found that decreasing the flow velocity and increasing its oxygen concentration, and/or increasing the radiant flux enhances the transition to flaming and reduces the time delay to transition. Limiting external conditions for the transition to flaming are reported for this experimental configuration. The results show that smolder propagation and transition to flaming can occur in relatively small fuel samples if the external conditions are appropriate. The results also indicate that transition to flaming occurs in the char region left behind by the smolder reaction, and it has the characteristics of a gas-phase ignition induced by the smolder reaction, which acts as the source of both gaseous fuel and heat. A simplified energy balance analysis is able to predict the boundaries between the transition/no transition regions.     

Combustion of slugs of propane and air moving up through an incipiently fluidized bed

A mathematical model is proposed to show the evolution of temperature, chemical composition and energy release or transfer in slugs, clouds and particulate phase, in a fluidized bed where there are slugs, of a mixture of air and propane, moving up through the particulate phase previously set in the state of incipient fluidization with air. The analysis begins as the slugs are formed at the orifices of the distributor, until they explode inside the bed or emerge at the free surface. The model also makes the analysis of what happens in the gaseous mixture that leaves the free surface of the fluidized bed until the propane is thoroughly burnt. It is essentially built upon a simple quasi-global mechanism for the combustion reaction and the mass and heat transfer equations from the two-phase model of fluidization. The aim was not to propose a new modelling approach, but to combine classical models, one concerning the reaction kinetics and the other the bed hydrodynamic aspects, to obtain a better insight on the events occurring inside a fluidized bed reactor, enhancing the understanding of this type of reactor. Experimental data to balance with the numerical model were obtained through tests on the combustion of commercial propane, in a laboratory scale fluidized bed, using four sand particle sizes: 400–500, 315–400, 250–315 and 200–250 μ m. The mole fractions of CO₂, CO and O₂ in the flue gases and the temperature of the fluidized bed were measured and compared with the numerical results.     

林火中的阴燃现象:研究前沿与展望

森林中的植物腐殖质和有机泥炭土的阴燃是地球上尺度最大的燃烧与火灾现象,造成了巨大的经济损失及跨国界的雾霾,并严重破坏了生态系统.本文综述了阴燃林火的基础燃烧理论和化学反应机理,总结了其点火、火蔓延和熄火的行为特性.同时,归纳了近年来泥炭阴燃火的研究动态,包括如何通过小尺度的阴燃实验理解大尺度的阴燃林火,如何构建阴燃的数...     

Mechanism and kinetics of lithium vapor capture in a high-temperature packed bed of kaolinite

This study investigated the characteristics of high-temperature lithium vapor-capturing reaction in a packed bed of calcined kaolin particles. The packed-bed sorption experiments were carried in the a temperature range of 700-900 °C. The high-temperature reaction between LiCl vapor and calcined kaolin sorbent generated lithium aluminum silicate (Li₂O·Al₂O₃·2SiO₂). An increase in kaolin bed temperature results in an increase in lithium-capturing rate, but it has no effect on the maximum lithium uptake. The resistance of LiCl vapor diffusion into the pores of calcined kaolin particles was negligible, and the chemical reaction at the kaolin surface controlled the overall sorption reaction rates by up to 60% of metakaolinite conversion. The order of the reaction between metakaolinite and LiCl vapor was determined as 1.94 and its activation energy was estimated as 7.95 kcal/mol according to the Arrhenius relationship.