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1.
少量H2对预混气着火的影响 总被引:2,自引:0,他引:2
对含有两种燃料气(H2和CH4)的预混气在热棒前驻点处的着火进行了研究,并与实验结果进行对比。CH4和水蒸汽首先在加热炉中发生催化重整反应,生成少量H2,再与空气预混后,在试验段出口处被热棒点燃。实验和计算结果都表明,H2的高反应率和高扩散性对着火有显著影响,大大降低了着火温度。据此提出了一种新的计算等效总体反应率的方法,同时采用热棒表面处的当地Damkohler数的梯度替代传统的温度梯度作为着火判据。 相似文献
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La2O3对CH4氧化的催化机制 总被引:2,自引:0,他引:2
本文研究了La2O3对CH4氧化燃烧和氧化偶联的催化机制。实验采用的是分子束技术,以及俄歇电子能谱(AES),四极柱质谱(QMS)和X射线光电子能谱(XPS)等表面分析技术。实验结果表明CH4分子的平动能和La2O3表面的晶格氧(O2-)是催化氧化CH4的两个关键因素。燃烧室内壁涂以稀土氧化物催化层将会提高燃烧效率和减少废气污染。 相似文献
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对CH4、水蒸汽和空气的预混气在涂有催化剂的热棒表面的着火进行了计算分析,并与实验结果作对比。实验和计算结果都表明,该催化剂使重整反应能够在较低温度下(200-500C)发生,产生少量H2。由于H2的高反应率和高扩散性对预混气性质育显著影响,大大降低了着火温度。对于改善烃类燃料的掺水燃烧有重要意义。传统的催化燃烧是用贵金属催化剂直接催化氧与燃料间的氧化反应,降低着火温度。与其不同,采用廉价含稀土的镍催化材料,催化燃料与水蒸汽的重整反应,使之在固体表面生成H2,利用H2来改善燃烧,是一种“间接”的催化燃烧。 相似文献
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用光纤燃烧传感器测量汽油机的燃烧时间参数的研究 总被引:2,自引:0,他引:2
本文介绍了一个光纤燃烧传感器及OMA4光多通道分析仪组成的测量系统,用以测量汽油机燃烧火焰光谱。光谱分析结果再次证实了燃烧火焰中CH(431.5nm),C2(516.5nm),H2O(589nm)等自由基的特征光谱同C粒子的热辐射连续光谱叠加在一起,构成了火焰光谱。根据光谱曲线中H2O光强峰值变化,可以确定汽油机燃烧过程中重要的时间参数:着火延迟期和燃烧持续期。由于汽油机燃烧循环变动大,与单色仪和BOXCAR积分平均器组成的测量系统相比,光纤燃烧传感器+OMA4用光多通道分析仪系统测量汽油机燃烧火焰光谱,测量精度高,工作效率高。 相似文献
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储热材料AlNH4(SO4)2.12H2O的过冷性实验研究 总被引:4,自引:0,他引:4
对储热材料AlNH4(SO4)2.12H2O添加成核剂CaF2及C时在不同冷却条件下进行了过冷性实验研究。 相似文献
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在一个流化床反应器和一个固定床反应器中研究了流化床煤燃烧中N2O及NOx生成的机理。发现流化床煤燃烧中N2O和NOx主要来自于煤中的氮,即挥发分氮和焦炭氮.部分NOx来自于空气中的N2.挥发分氮主要以两种形式HCN和NH3均相反应生成N2O和NOx;焦炭氮则以多种多相反应方式生成N2O和NOxN2O与NOx的消减机理有很大的区别。N2O主要通过为氢原子和氧原子的还原的反应、床层中各种固态物质的催化还原及自身的热分解而减少。NOx则通过在固态物质催化下与CO、H2、NH3和焦炭的反应而减少。 相似文献
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本文利用实验和求解化学热力学参数联合概率密度函数输运方程的方法,即概率密度函数(PDF)方法,研究并计算了NH_3-NO-O_2-N_2柱塞流中NO_x及N_2O的生成反应。PDF方法具有精确计算非线性化学反应速率的优势,很适合进行湍流燃烧中污染物生成反应的理论研究。本文采用差分和MonteCarlo相结合的方法求解PDF的输运方程,并考虑了详细的化学反应机理(共19个组分,73个基元反应)。计算结果和相应的实验数据进行了相互比较,二者较为吻合。结合实验和计算结果,分析了该柱塞流中影响NO-x及N_2O生成的主要基元反应和控制参数。 相似文献
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二氧化碳的等离子体化学固定化 总被引:4,自引:0,他引:4
二氧化碳排放控制和化学利用是全世界科学家面临的难题。人们已提出利用物理和生物方法来解决二氧化碳问题,但对二氧化碳这样一个巨大的碳资源,还没有特别有效的化学利用方法。在这方面,前人曾考虑过非均相催化。但非均相催化能耗大,而氢源紧缺;以及二氧化碳本身非常稳定,需高温激活,而高温又导致催化剂寿命很有限,很难达到工业化要求。而冷等离子体,包括各种气体放电现象,其某些作用方式类似于常规催化,但在低温高效激活二氧化碳方面更有效率。本文详细讨论了等离子体二氧化碳化学固定化的各种方法,包括直接法和间接法,并比较了等离子体法与常规催化方法的区别。讨论的物系包括:H2/CO2、CH4/CO2、H2O/CO2和H2S/CO2 相似文献
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拟闭式循环柴油机着火过程的研究 总被引:4,自引:0,他引:4
简要分析了以“人造大气”工作的闭式循环柴油机所需解决的技术问题和理论问题。针对发动机工作过程的特点,着重就工质成分对拟闭式循环柴油机自然着火过程的影响进行了实验和研究。结果表明,添加氩气有助于缩短冷焰和热焰诱导期,而工质中CO2浓度的增加则会延长冷,热焰诱导期;在着火滞燃期随工质成分而变化的趋势上,理论计算与实验测量基本相吻合。 相似文献
10.
生物质热裂解技术的实验研究 总被引:1,自引:0,他引:1
以木屑为原料,利用从荷兰引进的旋转锥反应器闪速热裂解装置进行了热裂解试验。对热裂解产物的组成及反应的物质平衡进行了分析。结果表明:木屑热裂解产物由生物油、不可冷凝气体和木炭组成。其中,生物油成分复杂,低热值为16 595kJ/kg;不可冷凝气体主要由CO,CH4 ,CO2 ,H2 和H2O蒸汽组成。在反应器温度为600℃,旋风机温度为500 ℃,旋转锥频率为10Hz 条件下,当木屑喂入率为26.42kg/h 时,生物油、不可冷凝气体及木炭的得率分别为53.37% ,21 .45% 和25.16% 。 相似文献
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《International Journal of Hydrogen Energy》2022,47(63):26789-26797
The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO2 and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized. 相似文献
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Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined. 相似文献
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基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁(MgO),研究了该型MgO膨胀剂(MEA)细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析(TG DSC)分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。 相似文献
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使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。 相似文献
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M.R. Salimpour M. SharifhasanE. Shirani 《International Communications in Heat and Mass Transfer》2011,38(1):93-99
This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed. 相似文献
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本文对漫灰均温物体在常物性条件下对外辐射传热的Yong值计算建立了数学模型。通过与物体内能Yong公式的数值计算比较,得出了辐射能量的Yong值不大于内能Yong值的结论。从初步的热射Yong值计算公式发现。Yong与物体表面辐射率有关。 相似文献
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《International Journal of Hydrogen Energy》2022,47(83):35515-35526
The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%. 相似文献
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General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996 相似文献