生物柴油热重分析及柴油机试验研究

利用热重分析仪在氮气及氧气气氛下,对生物柴油和0#柴油进行热分析,考查了样品的挥发热解及氧化特性,并计算热分析特性参数.对两种燃料进行了柴油机台架对比试验,并对燃烧特性数据进行分析.结果表明:生物柴油有良好的替代性;生物柴油的燃烧性能更加优越,使用在柴油机上时,较为提前的着火延迟期可以使柴油机工作柔和,不粗暴.热重法对燃料蒸发性能的研究对发动机缸内雾化蒸发和燃烧过程有着指导意义.     

不同气氛下柴油热解及热动力学特性分析

利用热重分析技术研究了不同载气流量、载气气氛和升温速率下柴油的热解过程.比较分析了单一反应模型和DAEM模型对柴油热解动力学分析的适应性.结果表明,单一反应模型不能在整个温度区间内对柴油热解特性进行预测;而DAEM模型可以由3条不同升温速率下的失重曲线直接得到不同失重率下柴油热解的活化能分布和频率因子的值,较为准确地求解动力学参数.由DAEM模型所得的不同气氛下活化能分布曲线表明,CO2气氛中柴油稳定性更好;柴油在CO2气氛中比N2气氛中热解速度大.     

生物油催化裂解的动力学分析

以CaO·MgO混合物为催化剂,采用热重分析法探讨了混合物中MgO含量对生物油催化裂解反应速度和最终残留率的影响.实验结果显示,生物油的热重变化过程可以分为室温～200℃范围内的挥发阶段和200～520℃范围内的热裂解阶段.在热裂解阶段中,反应速率常数和温度的关系可以用Ardaenius方程式表示.在MgO含量为50%的CaO·MgO混合物的催化作用下,生物油热裂解反应活化能从无催化剂时的20.9kJ/mol降低到16.5kJ/mol,最终相对残留率降低到0.75.MgO含量为38.7%的煅烧白云石是有效的生物油裂解催化剂.     

生物柴油燃烧化学动力学数值模拟

应用零维单区模型对生物柴油在发动机燃烧中的化学动力学过程进行了数值模拟,通过分析生物柴油在内燃机边界条件下燃烧氧化过程的关键基元反应、关键中间产物的生成速率(ROP)以及重要自由基,总结出了生物柴油燃烧氧化的主要反应路径.生物柴油的燃烧过程经历低温放热和高温放热两个阶段;在低温放热阶段生物柴油燃料主要通过脱氢反应进行消耗,在高温阶段则通过直接裂解和脱氢反应进行消耗,OH自由基无论在低温阶段还是在高温阶段对燃料的脱氢都起到了主导作用.     

乙醇柴油的热重分析及其排放特性研究

利用TGA(热重分析仪)以15℃/min的升温速率,分别在氮气及氧气气氛下,对0#柴油(D100)、以生物柴油作助溶剂的乙醇柴油(B10E10)、以复配乳化剂为助溶剂的乙醇柴油(R5E10)进行热分析,考察了样品的挥发热解及氧化特性,并计算热分析特性参数.对3种燃料进行了发动机台架对比试验,并对排放数据进行分析.结果表明:以生物柴油为助溶剂的乙醇柴油具有较好的热稳定性;相对普通柴油而言,乙醇柴油的失重特性指数较低,完全挥发氧化需要更高的温度.发动机台架试验也表明,当100％负荷时,柴油机燃用B10E10的排放得到改善,但是燃用R5E10时排放中的CO,HC略有升高.     

生物柴油和石化柴油喷雾特性的对比研究

采用相位多普勒粒子分析仪,从索特平均直径、喷雾锥角和喷雾贯穿距等方面对生物柴油和0#柴油的喷雾特性进行了对比研究.基于高速摄像技术,拍摄了几个典型时刻生物柴油和0#柴油的喷雾图片.结果表明:在相同的喷射条件下,生物柴油的索特平均直径和喷雾贯穿距大于0#柴油,而喷雾锥角小于0#柴油.     

柴油和生物柴油喷雾特性的对比研究

为了研究生物柴油与柴油在雾化质量方面的差异,在燃油雾化质量评价理论的基础上,采用高速摄像机和马尔文激光粒度分析仪对柴油、生物柴油的喷雾特性进行了对比研究;计算分析了喷雾发展的不同时刻的喷雾锥角、贯穿距离,以及喷雾液滴的尺寸体积分布、累计体积分布、特征直径、平均直径和发散边界。结果表明:由于生物柴油的运动粘度、密度和表面张力都大于柴油,所以生物柴油的贯穿距、平均直径、特征直径、发散边界都比柴油的大,喷雾液滴的尺寸体积分布曲线和累计体积分布曲线都偏向大颗粒方向,喷雾锥角和相对尺寸范围比柴油的小,这说明生物柴油的雾化质量差。     

生物柴油与石化柴油的性能对比研究

以脂肪酸甲酯为原料,制成不同比例的生物柴油B10,B20,B30和基准石化柴油在CA4DB1-10E3发动机上进行对比测试.试验结果表明,生物柴油可明显降低柴油发动机排出的PM,HC,CO,对NOx有些负面的影响,发动机功率随掺烧比例的增加而下降,油耗随掺烧比例的增加而增加.     

双金属络合物催化废油制生物柴油的动力学

高酸值废油与甲醇经过双金属氰基络合物催化同时发生酯化与酯交换反应可以制备生物柴油,以配位金属表示的催化剂活性顺序为锌>镍>铜>钴>(铅、铬).催化剂用量为3%,反应温度70℃,反应时间12h后转化率达78.2%(Fe-Zn).用气相色谱分析产物中甲酯的含量,发现反应温度和催化剂组成影响反应速率,在开始阶段接近二级反应,以后转为一级反应和零级反应.常压下65℃和70℃时速率常数分别为2.43、2.57mL·mol-1·min-1,活化能Ea=10.588kJ/mol.     

酯交换法制备生物柴油反应机理和影响因素分析

阐述了生物柴油的生产制备技术,从生物柴油酯交换合成反应出发,探讨了各种酯交换反应的反应机理;从原料油中的水分、游离脂肪酸、温度、压力、催化剂、反应时间、醇油比和原料混合程度等各个方面分析了对生物柴油制备的影响,得出了最佳的反应工艺条件。     

Preparation and thermal stability of ternary sulfate molten salt

以硫酸钠、硫酸钾和硫酸镁为原料,采用在硫酸钠-硫酸钾二元共晶盐中加入硫酸镁的方法制备三元硫酸熔盐。应用TG-DSC联用分析仪、热常数分析仪、X射线衍射仪以及热循环法对复合熔盐的熔点、相变潜热、热导率、比热容、分解点以及热稳定性进行表征。结果表明：所制备的三元硫酸熔盐熔点分布在667.5～669.7 ℃之间,较二元熔盐熔点降低了160 ℃左右,硫酸镁含量为30%（质量分数）的三元硫酸熔盐相变潜热值最大为94.3 J/g,比热容最大为1.13 J/(g·K)（720℃≤T≤800℃）,导热系数为0.41 W/(m·K),分解温度为1070 ℃,经50次热循环后,相变潜热值降低约4.34%,熔点和物相保持基本恒定,具有良好的热稳定性。该研究为硫酸盐作为高温传热蓄热介质提供了依据。     

Effect of hydrogen enrichment in the intake air of diesel engine fuelled with honge biodiesel blend and diesel

In the current investigation, the enrichment of hydrogen with the honge biodiesel blend and diesel is used in a compression ignition engine. The biodiesel is derived from the honge oil and mixed with diesel fuel by 20% (v/v). Thereafter, hydrogen at different volume flow rates (10 and 13 lpm) is introduced into the intake manifold. The outcomes by enrichment of hydrogen on the performance, combustion and emission characteristics are investigated by examining the brake thermal efficiency, fuel consumption, HC, CO, CO₂, NOₓ emissions, in-cylinder pressure, combustion duration, and rate of heat release. The engine fuelled with honge biodiesel blend is found to enhance the thermal efficiency, combustion characteristics. Compare to diesel, the BTE increased by 2.2% and 6% less fuel consumption for the HB20 + 13H₂ blend. Further, reduction in the emission of exhausts gases like CO and HC by 21% and 24%, respectively, are obtained. This is due to carbon-free structure in hydrogen. Moreover, due to high pressure in the cylinder, there is a slight increase in oxides of nitrogen emission compare to diesel. The combustion characteristics such as rate of heat release, combustion duration, and maximum ₂rate of pressure rise and in-cylinder pressure are high due to hydrogen.     

Kinetics of the thermal decomposition of Eucommia ulmoides Oliver leaves and its fermentation products

The pyrolysis characteristics of Eucommia ulmoides Oliver leaves untreated and treated by biological fermentation were investigated using thermogravimetric analysis. The derivative thermogravimetry curves, kinetic characteristics, and activation energy of the samples were significantly different from other biomass. The average activation energies (253.40 and 268.77 kJ/mol, 257.71, and 270.82 kJ/mol) were close almost similar to that obtained from Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa methods and were higher due to the presence of gutta-percha. Meanwhile, the decomposition and kinetic characteristics could be changed by fermentation technology. Besides, Coats–Redfern revealed that second-order model (f(α) = (1–α)²) could be used to better describe the decomposition mechanism of these samples.     

Verification of hydrothermal stability of adsorbent materials for thermal energy storage

This paper presents an experimental protocol for the cycling stability of adsorbent materials for thermal energy storage (TES) applications under hydrothermal conditions. Two different aging conditions were identified, namely, cycle and shelf test. The former one mimicking the cycling between desorption and adsorption conditions, while the latter one keeping a constant temperature for long time under constant water vapor pressure. A flexible experimental setup was then designed and realized to contemporarily perform both aging condition under selectable operating conditions. The protocol defines different characterization methods to compare the fresh and the aged samples. The measurement of the water vapor adsorption equilibrium isobars represents the main parameter to directly highlight possible degradation phenomena. Subsequently, X‐ray diffraction patterns (XRD), nitrogen physisorption, and scanning electron microscopy coupled to energy dispersive x‐ray (SEM–EDX), are used to evaluate structural, textural, morphological, and elemental composition variation that can help in identifying the causes of possible degradation. The proposed protocol was employed to validate the stability of a commercial adsorbent, AQSOA Z02, that proved a quite stable behavior both under cycle and shelf investigated conditions.     

火锅废油合成生物柴油的研究

以火锅废油为原料,通过单因数和正交实验,得出了以浓硫酸为催化剂进行酯交换的最优条件是:甲醇与废油物质的量比为9,硫酸量为废油质量的4%,反应时间为3h,反应温度为65℃。并采用气相色谱测定了产物的主要成分。     

生物柴油贮藏稳定性研究进展

贮藏稳定性是保证生物柴油质量和生物柴油作为交通运输及加热燃料进入市场的关键。文章总结了测定生物柴油贮藏稳定性的几种方法以及影响生物柴油贮藏稳定性的因素，并着重阐述了抗氧化剂对生物柴油贮藏稳定性的影响。     

Comparison of fuel characteristics of green (renewable) diesel with biodiesel obtainable from algal oil and vegetable oil

To fulfill the need of renewable, sustainable, and cleaner form of fuel, scientists are attracted toward biodiesel and hydrotreated vegetable oil or green (renewable) diesel. Biodiesel is generally obtained from vegetable oil by the process of transesterification while green diesel is obtained by hydrogenation. However, chemically both are completely different and thus their physical properties are highly affected. In present work, authors have compared the important properties of Pongamia biodiesel, algal biodiesel and hydrotreated vegetable oil. It is observed that both the biofuels may be blended for use in diesel engines as this will complement their fuel characteristics.     

Comparison of performance characteristics of agricultural tractor diesel engine operating on home and industrially produced biodiesel

Owing to unstable diesel fuel prices in the world market, many farmers have been looking for alternative fuels. Vegetable oils are one of the alternatives, which can be used as fuel in diesel engines either in the form of straight vegetable oil or in the form of biodiesel. This study aims to present experimental data by utilization of home and industrial biodiesel as fuel in an agricultural tractor diesel engine. The home biodiesel production was made from different vegetable oils (crude rapeseed, edible sunflower and waste oil) with the process of one‐stage‐based catalyzed transesterification. A commercially available agricultural tractor ZETOR 7745 was employed. Measurements were taken on the power take‐off shaft by electrical dynamometer FROMENT XT200. According to the results, agricultural tractor diesel engine operating on home biodiesel fuels had better performance characteristics related to industrially produced biodiesel and similar to conventional diesel fuel. Copyright © 2009 John Wiley & Sons, Ltd.     

An investigation of thermal behaviour of biomass and coal during co‐combustion using thermogravimetric analysis (TGA)

The thermal behaviour and kinetic analysis of biomass (cypress wood chips and macadamia nut shells) and Australian bituminous coal during combustion were studies using the thermogravimetric technique with four different heating rates under an air atmosphere. Each type of biomass was blended with coal at mass ratios (biomass:coal) of 95:5, 90:10, 85:15 and 80:20 to investigate the effect of coal as a supplementary fuel on thermal behaviour during the combustion process. Combustion of the individual samples and the blends took place in three steps comprising dehydration, devolatilisation and char oxidation. During co‐combustion, the thermal decomposition behaviour of the blends followed that of the weighted average of the individual samples in the blends. In kinetic analysis, thermal decomposition of biomass and coal appeared to take place independently, and thus, the activation energy of the blends can be calculated from that of the two components. No evidence for any significant synergetic effects or thermal interaction was found between either type of biomass and the coal during co‐combustion based on the lack of deviation from expected behaviour of the blends. Copyright © 2013 John Wiley & Sons, Ltd.     

Nonlinear thermal stability of eccentrically stiffened FGM double curved shallow shells

This article presents analytical solutions for the nonlinear static and dynamic stability of imperfect eccentrically stiffened functionally graded material (FGM) higher order shear deformable double curved shallow shell on elastic foundations in thermal environments. It is assumed that the shell’s properties depend on temperature and change according to the power functions of the shell thickness. The shell is reinforced by the eccentrically longitudinal and transversal stiffeners made of full metal. Equilibrium, motion, and compatibility equations are derived using Reddy’s higher order shear deformation shell theory and taking into account the effects of initial geometric imperfection and the thermal stress in both the shells and stiffeners. The Galerkin method is applied to determine load–deflection and deflection–time curves. For the dynamical response, motion equations are numerically solved using Runge–Kutta method. The nonlinear dynamic critical buckling loads are found according to the criterion suggested by Budiansky–Roth. The influences of inhomogeneous parameters, dimensional parameters, stiffeners, elastic foundations, initial imperfection, and temperature increment on the nonlinear static and dynamic stability of thick FGM double curved shallow shells are discussed in detail. Results for various problems are included to verify the accuracy and e?ciency of the approach.