低温燃料化学特性对湍流预混火焰传播的影响

大分子碳氢燃料的低温化学反应及两阶段点火特性会显著影响火焰的分区及燃烧情况。本文采用数值模拟的方法探究了正庚烷/空气预混混合气在RATS燃具上的湍流火焰传播,与试验结果具有一致性。模拟使用的是44种物质,112步的正庚烷简化动力学机理。使用Open FOAM的reacting Foam求解器建立了简化模拟流道及出口的三维模型,模拟了在大气环境下,初始反应温度450–700 K、入口速度6 m·s~(-1)与10 m·s~(-1)、焰前流动滞留时间100 ms及60 ms、当量比φ=0.6的正庚烷/空气混合气湍流火焰燃烧情况。结果发现,标准化湍流燃烧速度与混合气初始温度以及流动滞留时间有关。在低温点火阶段,正庚烷氧化程度受到初始温度与速度的影响,燃料分解并在预热区中产生大量中间物质如CH_2O,继而会影响湍流火焰燃烧速度。随着初始反应温度的升高,湍流燃烧火焰逐渐由化学反应冻结区过渡到低温点火区;温度超过一定数值后,燃料不再发生低温反应,此时燃烧位于高温点火区域。     

界面膜引发的乳化燃油燃烧中的振荡反应

有关小分子醇、H。和CO等易燃气体在铂催化下的高温燃烧的温度振荡及以表面活性剂为关键组分的液膜扩散振荡已有报道"－'－．但由界面膜作用而产生的乳化燃油燃烧中的振荡反应尚无其它可操作的原始研究文献,只是在前文［'j中提及过出现该现象．为了解乳化燃油燃烧过程中界面变化及其对燃烧的作用,通过静态燃烧实验配方的调节及变换以改变燃烧界面的情况．实验发现,在乳化燃油中加入一般的食用豆油,并使之水解出长链竣酸盐,则富集在燃烧界面上的长链竣酸盐所形成的界面膜对燃烧的自阻抑作用便会产生明显的振荡反应,形成火焰温度与高…     

旋流煤粉燃烧的一维综合数值模拟

发展了综合考虑气－固两相旋流流动，气相燃烧，颗粒相变与燃烧及两相辐射传热的旋流煤粉燃烧－维数学模型，给出了气－固两相能量方程中颗粒相就源项的计算表达式，应用这一模型对涡旋燃烧炉环形通道内多组工况的旋流气体燃烧和煤粉燃烧进行了数值模拟，计算得到的炉内温度分布和燃烧效率与实验数据基本相符，表明本文建立的模型可用于旋流煤粉燃烧的一维综合数值模拟。     

第四届亚洲流体力学会议在香港举行

第四届亚洲流体力学会议(4ACFM)1989年8月21～25日于香港大学召开。会议共发表学术论文350篇,内容涉及边界层理论、湍流流动、喷嘴流动、涡旋流动、两相流动、非牛顿流动和流动传热等领域。来自     

用示差热天平测定油煤混合物的燃烧特性

为节约燃料油,在部分燃油设备中改用油煤混合物(COM)是目前可能采取的一种有效措施。因煤与油的燃烧特性不同,而油煤混合物并非简单的机械混合。因而,进行一些测定与分析,可为改造设备及以后操作提供部分依据。本文简要介绍了煤粉及油雾燃烧的一般机理,并分析影响其起燃及燃尽因素。通过示差热天平对烟煤煤粉、渣油及不同比例的COM在一定加热条件下失重与差热试验,认为COM的燃烧情况与煤粉不尽相同。在同样加热条件下,掺入煤粉越多,所需燃尽时间越长,但并非正比关系。在COM的热整曲线上,在450°—500℃间出现激烈的热量波动,文中对此进行了讨论。在采用COM代替燃油时,可根据原燃烧空间情况及燃料油、煤与COM的差热失重曲线的数据,来分析燃烧中的问题。     

燃烧源PM2.5凝结洗涤脱除实验研究

利用蒸汽在燃烧源PM2.5表面凝结,促使PM2.5凝结长大,建立一套燃烧源PM2.5凝结洗涤的实验台;考察了颗粒粒径分布、蒸汽添加量、液气比等对两种燃烧源PM2.5凝结洗涤脱除效果的影响。采用电称低压冲击器 (ELPI)在线测试分析燃煤和燃油PM2.5凝结洗涤前后的数浓度和粒径分布特性,并用SEM和XPS对两种不同燃烧源的颗粒进行了形貌和元素组分分析。结果表明,燃煤和燃油产生的PM2.5形貌和组分具有较大的差别,燃煤PM2.5主要为硅铝矿物质,而燃油PM2.5主要为含炭物质;相同条件下,燃煤PM2.5相变脱除效果优于燃油PM2.5;随着蒸汽添加量的增加,两者的脱除效率均升高;随粒径的增大,脱除效率提高;蒸汽添加量为0.08kg/m3时,粒径为0.4μm的燃煤和燃油细颗粒的脱除效率分别81％和72％;此外,适当增加液气比有利于凝结长大含尘液滴的脱除。     

煤浆燃烧、流动、传热和气化的理论与应用技术

该书是以中国工程院院士岑可法教授为首，组织９名专家学者撰写的专著。全书共有１７章，１７５万字（详见简介），内容十分丰富，是目前国际上第一本全面系统介绍煤基浆状燃料在管内流动、传热及在锅炉内燃烧、气化的原理，计算方法及工作应用技术方面的专业著作，由浙江...     

燃烧反应动力学研究进展

化学反应动力学是燃烧过程分析的重要工具。燃烧微观反应过程、复杂反应机理、燃烧实验测量和湍流燃烧数值模拟等方面的研究工作已经取得了长足进步。本文主要介绍燃烧反应动力学研究方法,包括电子结构方法、燃烧反应热力学和速率常数的计算方法、燃烧详细机理构建和简化、反应力场分子模拟以及燃烧中间体测量、燃料点火延迟和光谱诊断等方面的研究现状。燃烧反应动力学具有很强的应用背景,燃烧过程化学物种的反应速率计算是湍流燃烧数值模拟的一个中心任务。由于燃烧反应网络的高度复杂性,我们对燃烧机理的认识还远不清楚。化学反应和湍流相互作用研究的深入、燃烧反应动力学和计算流体力学的协同发展,将对新燃料设计、燃烧数值模拟、发动机内流道流场结构的准确描述产生深远影响。     

预混天然气在多孔介质燃烧器中的燃烧与传热

在一台小型渐变型多孔介质燃烧器上进行了预混天然气燃烧与传热试验研究,探讨了天然气速度和多孔介质厚度对多孔介质燃烧室的温度分布、排烟温度和流动阻力的影响。结果表明,天然气在渐变型多孔介质燃烧器中燃烧稳定,燃烧室与水冷夹套间的换热受天然气速度和多孔介质厚度影响,换热效果比空管中燃烧明显增强,同时预混天然气通过多孔介质的进出口压差随着天然气速度和多孔介质厚度的增加而增加。     

分析测试新成果(230~237)2种常见燃油添加剂对汽油燃烧烟尘的影响

采用气相色谱-质谱(GC-MS)联用技术,根据汽油原样中的特征成分,对未加入和分别加入汽油燃油精、海龙燃油宝的汽油燃烧烟尘进行对比分析.结果表明,汽油燃油精的加入会使汽油燃烧烟尘中各类特征成分的百分含量有所变化,但对谱图和特征成分的影响较小;而海龙燃油宝的加入对汽油燃烧烟尘的谱图、特征成分及其个数、各类特征成分的百分含量均产生较大影响.结果为火灾物证鉴定提供一定的参考依据.     

中国硫回收技术进展(英文)

综述了国内硫回收技术的现状,并对今后１０－１５年内硫回收技术的发展进行了展望。     

INCREASED UV EXPOSURE IN FINLAND IN 1993

Abstract—
Exceptionally low total ozone, up to 40% below the normal level, was measured over Northern Europe during winter and spring in 1992 and 1993. In 1993 the depletion persisted up to the end of May, resulting in a significant increase of biologically effective UV radiation. The increases were significantly smaller in 1992 and 1994 than in 1993. The UV exposure of the Finnish population was evaluated through measurements and theoretical calculations. The increase in measured erythemal (International Lighting Commission) UV falling onto horizontal surfaces on clear days was determined relative to model calculations for an average ozone amount. The increase was on average 10% from April to May 1993, and the maximal measured increase was 34%. Theoretical calculations for both erythemal and carcinogenic (Skin Cancer Utrecht-Philadelphia) UV indicated that in 1993 the theoretical annual increase to a vertical (cylinder) surface ranged from 8 to 13% in Finland. The reflection of UV from snow considerably increases facial UV doses in Northern Finland.     

COLLOID CHEMISTRY IN PETROLEUM INDUSTRY IN CHINA

Wool-wax alcohols are remarkably effective in stabilization of water-in-oil emulsions. The structural changes in the continuous phase have been analysed by X-ray diffraction technique between the emulsification temperature, when the alcohol phase is liquid, down to room temperature. Evidence is given for the formation of sterol multilayer structure at the oil/water interface. The bilayer thickness of the sterols is 34,3 Å, and at about 37 °C there is a transition into a phase with X-ray data in close agreement with these of anhydrous cholesterol. The aliphatic alcohol molecules, which thus separate from the sterol molecules, start to form an ordered structure at about 50 °C. First a lamellar liquid-crystalline phase is formed with a bilayer thickness of 41,1 Å. Ano α-crystal phase, with hexagonal chain packing and vertical molecules is formed at further cooling to about 40 °C. The relation between emulsion stability and ordered interfacial structure is discussed.     

ICP-AES 法测定我国三个不同地域生长的板栗中20种元素

应用ICP—AES测定了我国三个不同地域生长的板栗中20种无机元素的含量并作了成分的比较研究,对试样的溶解条件及仪器的工作参数也进行了研究和优化。各元素分析结果的RSD值在0．11％～6．9％之间,回收率在95．1％～108．0％之间。     

食品中氯丙醇测定方法研究进展

对食品中氯丙醇的检测方法进行了探讨,包括气相色谱法、气相色谱-质谱联用法、顶空-气相色谱法等,并针对样品处理所用衍生化方法作了详细介绍及对比。     

RHODOPSIN-PHOSPHOLIPID INTERACTION IN DETERGENT AND IN THE DISK

Abstract— Solubilization of cattle disk membrane in deoxycholate shifted the fluorescence emission maximum from 324 to 331 nm without changing the intensity. Tryptophyl residues are probably located at the hydrophobic interface between rhodopsin and phospholipid. Depletion of deoxycholate concentration from the solubilized disk by Sephacryl 200 column chromatography produced rhodopsin-phospholipid complexes with different characteristics that are the intermediate stages of membrane formation from homogeneous molecular solution. Association of rhodopsin takes place in a two-dimensional way even in the appreciably low content of phospholipid.
Sedimentation velocity studies showed that reassociation of lipid and rhodopsin occurs in 0.2% deoxycholate as well as in 0.05% sodium dodecylsulfate.
By using Sephacryl column we can now prepare, within 60 min, the rhodopsin-lipid complex that can form large vesicles in response to the addition of MgCl₂ without dialysis. This type of lipoprotein complex will be useful to the study of the mechanism of the two dimensional membrane formation.     

TRANSPORT OF LIGHT IN TISSUE IN PHOTODYNAMIC THERAPY

Abstract The dose rate in photodynamic therapy is proportional to the energy fluence rate and the concentration of the photosensitizer. Calculations of the energy fluence rate have been performed in slab, cylindrical and spherical geometries with the discrete ordinates transport method and diffusion theory. The attentuation of the energy fluence rate is least in slab geometry and greatest in spherical geometry. Violet (405 nm) light is attenuated much more rapidly than red (630 nm) light. Small tissue dimensions or narrow beam irradiation further decrease the energy fluence rate with radius and depth. Anisotropic scattering increases the energy fluence rate at large depths, but decreases it near the source. Measurements of the absolute energy fluence rate vs depth in a mouse tumor model exhibit an order of magnitude attenuation through the skin and a 3 mm thick tumor. Calculations of the energy fluence rate of the DHE fluorescence have been carried out to guide measurement of the concentration. Violet light excitation is much more efficient than red light excitation.