Ignition and combustion characteristics of aluminum/manganese iodate/nitrocellulose biocidal nanothermites

Journal of Thermal Analysis and Calorimetry - The traditional energetic materials are insufficient to sterilize the deleterious microorganisms carried by biological weapons completely. Three kinds...     

JP-10点火延时的激波管研究

JP-10 (exo-tetrahydrodicyclopentadiene, C10H16) ignition delay times were measured in a preheated shock tube. The vapor pressures of the JP-10 were measured directly by using a high-precision vacuum gauge, to remedy the difficulty in determining the gaseous concentrations of heavy hydrocarbon fuel arising from the adsorption on the wall in shock tube experiments. The whole variation of pressure and emission of the OH or CH radicals were observed in the ignition process by a pressure transducer and a photomultiplier with a monochromator. The emission of the OH or CH radicals was used to identify the time to ignition. Experiments were performed over the pressure range of 151-556 kPa, temperature range of 1000-2100 K, fuel concentrations of 0.1%-0.55% mole fraction, and stoichiometric ratios of 0.25, 0.5, 1.0 and 2.0. The experimental results show that for the lower and higher temperature ranges, there are different dependency relationships of the ignition time on the temperature and the concentrations of JP-10 and oxygen.     

Ignition and combustion characteristics of compound of magnesium and boron

Compound of magnesium and boron (MB) is promising to be the ideal substitute of amorphous boron which is usually used as the raw material of boron-based fuel-rich propellants. In this study, the physical characteristics of MB and amorphous boron were studied by the scanning electron microscope, X-ray diffraction and X-ray photoelectron spectroscopy. The thermal reaction characteristics and the ignition and combustion characteristics were investigated through TG/DSC experiments and laser ignition experiments. The experimental results show that the MB particle is much more regular than amorphous boron, which favors for the preparation of boron-based fuel-rich propellants. Magnesium exists in the form of elementary substance, and boron oxide is produced during the preparation of MB which results in the longer ignition delay time of MB. The content of magnesium and the pressure have effects on the MB combustion performance. Although the combustion of magnesium can provide much heat for the combustion of boron, MB with moderate content of magnesium shows the best combustion performance. On the contrast, the ignition delay time of MB is independent on the content of magnesium and the pressure.     

正构烷烃/JP-10二元体系的体积性质

利用Anton PaarDMA55和Ubbelohde黏度管分别测定了正辛烷和正癸烷两种正构烷烃与挂式四氢双环戊二烯{C10H16, exo-tricycle[5.2.1.02.6]decane(JP-10)}组成的二元体系在298.15 K下的密度和黏度, 计算了正构烷烃/JP-10二元体系的超额摩尔体积、组分的表观摩尔体积和偏摩尔体积等体积性质以及组分对超额体积的贡献, 研究结果表明, 烷烃的加入使得二元体系的超额体积均为负值. 根据Eyring液体黏性流动理论, 关联了二元体系的黏滞性活化参数, 结果表明, 熵驱动起主要作用. 从分子间相互作用角度讨论了二元体系体积性质的变化规律.     

燃烧反应过程中胜利脱灰褐煤微结构演变特性研究

对胜利脱灰褐煤的燃烧反应性进行了测试,并利用FT-IR、XPS、XRD和Raman等对不同条件下的未反应残留物进行了表征,以分析胜利脱灰褐煤在燃烧过程中微结构演变特性。结果表明,在燃烧反应过程中,煤样的脂肪族官能团不断消耗,碳氧官能团和芳烃骨架的消耗与生成交替进行,褐煤表面C-C/C-H键合结构所占比例先增加后减少,碳-氧键合结构所占比例先减小后增加,未反应残留物的芳香度不断升高,褐煤的石墨缺陷指数先增加后降低,而脂肪族侧链指数则呈现先减少后增加的变化规律,表明随着燃烧反应进行对褐煤未反应残留物的石墨化程度逐渐提高,特别是在燃烧反应后期,石墨化程度显著提高。     

Effects of equivalence and fuel ratios on combustion characteristics of an RCCI engine fueled with methane/n-heptane blend

Rising fuel costs and efforts for reducing greenhouse gases have led researchers to propose optimized models of combustion which have high efficiency and low emissions. Reactivity controlled compression ignition (RCCI) engines are attractive due to their high efficiency and low NO_x and soot emissions over a wide range of operating conditions. In this study, methane and n-heptane are used as low and high reactive fuels, respectively, to create suitable fuel stratification within the cylinder. Modeling is carried out by AVL FIRE coupled with a chemical kinetics solver to investigate the effects of fuel ratio, initial temperature and equivalence ratio on the combustion performance and emission characteristics. Methane/n-heptane ratios are varied according to the energy ratio of each fuel while total input energy and total equivalence ratios are fixed. By increasing methane energy ratio from 65% to 85% in the constant intake temperature and pressure, the mixture Octane number increases, which would lead to an increase in ignition delay up to 5 crank angles. As a result, IMEP would be enhanced and also NO_x emission decreases because of lower combustion temperature. By increasing intake temperature, the maximum in-cylinder pressure, heat release rate and NO_x emission would increase significantly while soot emission decreases, and also ringing intensity increases up to 10%. On the other hand, increasing intake temperature reduces volumetric efficiency; as a result, IMEP is reduced by 11%. Also by increasing equivalence ratio from 0.35 to 0.55 in a constant energy ratio, noticeable growth in the maximum amount of pressure and temperature could be achieved; consequently, NO_x emission would increase significantly, IMEP increases by 43%, and ISFC decreases by 30%. The results indicate that these parameters have significant effects on the heavy-duty RCCI engine performance and emissions.

     

两类药渣的水热提质效果及其燃烧特性研究

以中药药渣（HTW）与抗生素药渣（PMW）为对象,采用X射线光电子能谱、热重分析仪、量热仪与傅里叶红外分光光度计等技术分析两类药渣的差异并探究水热处理对药渣的提质效果与作用机理。结果表明,HTW含有大量木质纤维类成分,而PMW则以蛋白质与多糖为主;尽管这两类组分在水热提质中的转化途径有所区别,但均能提高药渣的热值（HTW：从19.4到26.2 MJ/kg;PMW：从19.1到29.3 MJ/kg）。同时,药渣的煤化程度随温度的上升而增加,甚至能接近烟煤水平。此外,由于水热过程中的脱挥发分与芳构化作用使得药渣中低能量的碳氢键转变为高能量的碳碳双键,不仅改善了药渣的燃烧性能,还使药渣在燃烧过程更为稳定且充分。     

Effects of ionomer coverage on agglomerate effectiveness in catalyst layers of polymer electrolyte fuel cells

A large proportion of voltage losses in polymer electrolyte fuel cells (PEFCs) originates in cathode catalyst layers. Catalyst utilization and performance of conventional catalyst layers depend largely on their ionomer content and distribution. The present study explores effects of agglomerate size and ionomer distribution on reaction rate distributions and effectiveness factor of Pt utilization. To study the oxygen reduction reaction, we have developed an agglomerate model, which consists of coupled relations for proton and oxygen transport, metal charging behavior, and interfacial charge transfer kinetics. The model is considered under steady state conditions. Results show that higher effectiveness factor is attained for agglomerates with smaller size and larger oxygen partial pressure on the surface. In addition, low to medium coverage of the ionomer skin layer is beneficial in view of high effectiveness factors due to the optimized interplay of oxygen and proton supply.     

Thermal decomposition and combustion characteristics of Al/AP/HTPB propellant

Journal of Thermal Analysis and Calorimetry - Aluminum(Al)/ammonium perchlorate(AP)/hydroxyl-terminated polybutadiene (HTPB) propellant is the most widely used propulsion system currently. Its...     

Filtration combustion of solid fuel in countercurrent reactors

The works studying filtration combustion of solid fuels in the countercurrent mode are reviewed. The phenomenon of superadiabatic overheating is described. The data of experimental and theoretical studies and some results of the development of technological processes of production of thermal or electric energy from substandard raw materials and extraction of valuable components (for example, rare metals) from unconventional sources (industrial wastes, poor ores, burrows, etc.) are presented. The processes of safe treatment of problematic wastes are considered.     

Pd/MWCNTs贫燃甲烷催化燃烧性能研究

以MWCNTs为载体,用HNO_3做氧化剂对MWCNTs进行处理,通过XPS研究了处理前后MWCNTs表面官能团的变化,并采用超声浸渍法制得Pd/MWCNTs催化剂,借助TEM,揭示了Pd粒子在催化剂表面分散度和粒径与MWCNTs表面含氧量、羟基和羰基间的关系。并考察了Pd/MWCNTs催化剂预处理方法对低浓甲烷催化燃烧活性和稳定性的影响,研究表明,Pd的价态以及Pd粒子的粒径,都与催化剂的甲烷燃烧活性直接关联。单质Pd的氧化和Pd粒径的长大是导致催化剂性能衰减的原因。通过原位FT-IR技术对反应气氛下中间物种的监测,提出了Pd/MWCNTs催化剂上的低浓度甲烷催化氧化反应机理。     

A review on fuel cell types and the application of nanofluid in their cooling

Journal of Thermal Analysis and Calorimetry - The application of nanofluid in cooling systems is increasing. The nanofluid consists of a mixture of nanometallic and nonmetallic particles, which...     

生物油/乙醇混合燃料燃烧性能研究

在空气气氛下采用热失重技术研究生物油及其与乙醇混合燃料的燃烧性能,利用Achar微分法和Coats-Redfern积分法结合的方式进行动力学分析,并对热解焦炭的物化特性进行了测量。结果表明,生物油及其与乙醇混合燃料的燃烧可分为三个阶段,即轻组分挥发、重组分裂解和焦炭燃烧;随着升温速率的升高,生物油的挥发性能和燃烧性能提高;随着乙醇质量分数的增加,挥发段和焦炭燃烧段的活化能都呈先减小后增大的趋势;混合燃料中乙醇质量分数不宜超过26%,否则其燃烧段的活化能增大,且热解焦炭所含有机官能团强度变弱,燃烧性能反而变差。     

Study on combustion characteristics of bio-oil/ethanol blends

在空气气氛下采用热失重技术研究生物油及其与乙醇混合燃料的燃烧性能,利用Achar微分法和Coats-Redfern积分法结合的方式进行动力学分析,并对热解焦炭的物化特性进行了测量.结果表明,生物油及其与乙醇混合燃料的燃烧可分为三个阶段,即轻组分挥发、重组分裂解和焦炭燃烧；随着升温速率的升高,生物油的挥发性能和燃烧性能提高；随着乙醇质量分数的增加,挥发段和焦炭燃烧段的活化能都呈先减小后增大的趋势；混合燃料中乙醇质量分数不宜超过26％,否则其燃烧段的活化能增大,且热解焦炭所含有机官能团强度变弱,燃烧性能反而变差.     

Pore scale modelling of a cathode catalyst layer in fuel cell environment: agglomerate reconstruction and variables optimization

Journal of Solid State Electrochemistry - In this work, a new strategy is adopted to optimize the cathode catalyst layer of a PEM fuel cell and to analyse the impact of three pertinent design...     

Sulfur evolution from coal combustion in O2/CO2 mixture

O₂/CO₂ coal combustion technology is considered as one of the most promising technologies for CO₂ sequestration due to its economical advantages and technical feasibility. It is significant to study the sulfur transfer behavior of coal in O₂/CO₂ atmosphere for organizing combustion properly and controlling SO₂ emission effectively. To clarify the effect of atmosphere on the sulfur transfer behavior, thermogravimetry coupled with Fourier Transform Infrared (TG-FTIR) system was employed to study the formation behavior of sulfur-containing gas species from Xuzhou bituminous coal pyrolysis in CO₂ atmosphere compared with that in N₂ atmosphere. Also the SO₂ formation behaviors during Xuzhou bituminous coal combustion in O₂/N₂ and O₂/CO₂ atmospheres were investigated. Results show that COS is preferentially formed during the coal pyrolysis process in CO₂ atmosphere rather than in N₂ atmosphere. When temperature is above 1000 K, sulfate in the CO₂ atmosphere begins to decompose due to the reduction effect of CO, which comes from the CO₂ gasification. During coal combustion process, replacing N₂ with CO₂ enhances the SO₂ releasing rate. SO₂ emission increases first and then decreases as O₂ fraction increases in the O₂/CO₂ mixture. XPS result of the ash after combustion indicates that higher O₂ concentration elevates the sulfur retention ability of the mineral matter in the coal.     

The performance,emissions, and combustion characteristics of an unmodified diesel engine running on the ternary blends of pentanol/safflower oil biodiesel/diesel fuel

Journal of Thermal Analysis and Calorimetry - The objective of the present study is to scrutinize the influence of a binary blend of diesel–safflower oil biodiesel and ternary blends of...     

Insight into the combustion mechanism of nitroglycerin/nano-aluminum composite materials

Structural Chemistry - The ReaxFF-lg is used to simulate the thermal decomposition of the pure nitroglycerin (NG) and nitroglycerin/nano-Al (NG/Al) systems. The simulation results show that the...     

Stability and magnetization of Fe3O4/water nanofluid preparation characteristics using Taguchi method

Journal of Thermal Analysis and Calorimetry - In this paper, the effect of different parameters on Fe3O4/water nanofluid preparation characteristics is investigated experimentally. Two criteria,...