Oxidation of Sulphur pollutants in model and real fuels using hydrodynamic cavitation

Hydrodynamic Cavitation (HC) offers an attractive platform for intensifying oxidative desulphurization of fuels. In the first part of this work, we present new results on oxidising single ring thiophene in a model fuel over the extended range of volume fraction of organic phase from 2.5 to 80 v/v %. We also present influence of type and scale of HC device on performance of oxidative desulphurization. Further experiments revealed that oxidising radicals generated in-situ by HC alone were not able to oxidise dual ring thiophenes. External catalyst (formic acid) and oxidising agents (hydrogen peroxide, H₂O₂) were therefore used with HC. Based on our prior work with acoustic cavitation (AC), the volumetric ratios for H₂O₂ and formic acid were identified as 0.95 v/v % and 6.25 v/v % respectively. The data of oxidation of dual ring thiophenes with n-dodecane and n-hexane as model fuels and typical transport fuels (diesel, kerosene, and petrol) using these oxidant and catalyst is presented. The observed performance with HC was compared with results obtained from a stirred tank and AC set-up. The presented data indicates that HC is able to intensify oxidation of sulphur species. The presented results provide a sound basis for further developments on HC based oxidative desulphurization processes.     

Visible Raman spectroscopy for the discrimination of olive oils from different vegetable oils and the detection of adulteration

We have investigated the potential of Raman spectroscopy with excitation in the visible spectral range (VIS Raman) as a tool for the classification of different vegetable oils and the quantification of adulteration of virgin olive oil as an example. For the classification, principal component analysis (PCA) was applied, where 96% of the spectral variation was characterized by the first two components. A significant similarity between sunflower oil and extra‐virgin olive oil was found using this approach. Therefore, sunflower oil is a potential candidate for adulteration in most commercially available olive oils. Beside the classification of the different vegetable oils, we have successfully applied Raman spectroscopy in combination with partial least‐squares (PLS) regression analysis for very fast monitoring of adulteration of extra‐virgin olive oil with sunflower oil. Different mixtures of extra‐virgin olive oil with three different sunflower oil types were prepared between 5 and 100% (v/v) in 5% increments of sunflower oil. While in the present context the adulteration usually refers to the addition of reasonable amounts of the adulterant (given the similarity with the basic product), we show that the technique proposed can also be used for trace analysis of the adulterant. Without using techniques like surface‐enhanced Raman scattering (SERS), a quantitative detection limit down to 500 ppm (0.05%) could be achieved, a limit irrelevant for adulteration in commercial terms but significant for trace analysis. The qualitative detection limit even was at considerably lower concentration values. Based on PCA, a clear discrimination between pure extra‐virgin olive oil and olive oil adulterated with sunflower oil was achieved. The adulterant content was successfully determined using PLS regression with a high correlation coefficient and small root mean‐square error for both prediction and validation. Copyright © 2009 John Wiley & Sons, Ltd.     

基于自加权交替三线性分解的荧光检测油类污染物

设计水中油类污染物检测仪,采用脉冲氙灯作为光源,选择阶跃型多模纯石英光纤对激发光和发射光进行传输。采用非对称Czemy-Turner光路的高精度光栅单色器。应用该装置测定柴油、汽油和煤油的荧光光谱,0#柴油、97#汽油和煤油的最佳激发波长/发射波长分别为：290/330,270/300和280/330 nm。检出限：柴油(0.025 mg·L-1)、汽油(0.042 mg·L-1)和煤油(0.054 mg·L-1)。相对误差：柴油(2.55%),汽油(2.06%)和煤油(1.71%),实验表明所设计的检测仪具有较高的测量精度。配置不同浓度的柴油、汽油和煤油的混合溶液,测量其三维荧光光谱,采用自加权交替三线性分解算法对光谱数据进行分解,预测浓度及回收率均表明自加权交替三线性分解算法对混合油类物质有较高的分辨能力。     

Quantification of Ethanol in Ethanol-Petrol and Biodiesel in Biodiesel-Diesel Blends Using Fluorescence Spectroscopy and Multivariate Methods

Ethanol blended petrol and biodiesel blended diesel are being introduced in many countries to meet the increasing demand of hydrocarbon fuels. However, technological limitations of current vehicle engine do not allow ethanol and biodiesel percentages in the blended fuel to be increased beyond a certain level. As a result quantification of ethanol in blended petrol and biodiesel in blended diesel becomes an important issue. In this work, calibration models for the quantification of ethanol in the ethanol-petrol and biodiesel in the biodiesel-diesel blends of a particular batch were made using the combination of synchronous fluorescence spectroscopy (SFS) with principal component regression (PCR) and partial least square (PLS) and excitation emission matrix fluorescence (EEMF) with N-way Partial least square (N-PLS) and unfolded-PLS. The PCR, PLS, N-PLS and unfolded-PLS calibration models were evaluated through measures like root mean square error of cross-validation (RMSECV), root mean square error of calibration (RMSEC) and square of the correlation coefficient (R ²). The prediction abilities of the models were tested using a testing set of ethanol-petrol and biodiesel-diesel blends of known ethanol and biodiesel concentrations, error in the predictions made by the models were found to be less than 2%. The obtained calibration models are highly robust and capable of estimating low as well as high concentrations of ethanol and biodiesel.     

多种薄油膜光谱反射率特性外场测试方法及结果分析

水面溢油机载航测工作需要以全面的溢油模拟目标的光谱反射率特性数据作为支撑,选择合适的工作波段,并通过获得的数据对溢油情况进行分析与判断。针对汽油、柴油、润滑油、煤油与原油五种目标样本,油膜从紫外波段到近红外波段进行了反射光谱测量,并将结果与相同实验环境下的水的反射光谱对比。实验结果表明油膜的光谱反射特性与油品类型以及油膜的厚度相关。不同种类的油膜在相同厚度的情况下,光谱反射率曲线的差异很大,而同一种类的油膜,随着油膜厚度的改变,光谱反射率曲线亦随之发生改变,因而就单一油膜而论,可以通过反射率曲线区分不同的油膜厚度。以相同的油膜厚度而论,柴油,煤油,润滑油在380 nm附近存在反射率峰值,与水的反射率差异明显,原油在大于340 nm波长的反射率远小于水,所得到的反射光谱能够在一定程度上区分不同类型油膜。实验涉及主要溢油油种,数据全面覆盖探测常用的光谱波段,定量化描述了油膜光谱反射率特性,为机载水面溢油探测工作的波段选择与水面溢油的早期发现与分析提供了全面的理论与数据支持。     

Simulations of laminar non-premixed flames of kerosene with hot combustion products as oxidiser

The effects of hot combustion product dilution in a pressurised kerosene-burning system at gas turbine conditions were investigated with laminar counterflow flame simulations. Hot combustion products from a lean (φ = 0.6) premixed flame were used as an oxidiser with kerosene surrogate as fuel in a non-premixed counterflow flame at 5, 7, 9 and 11 bar. Kerosene-hot product flames, referred to as ‘MILD’, exhibit a flame structure similar to that of kerosene–air flames, referred to as ‘conventional’, at low strain rates. The Heat Release Rate (HRR) of both conventional and MILD flames reflects the pyrolysis of the primary and intermediate fuels on the rich side of the reaction zone. Positive HRR and OH regions in mixture fraction space are of similar width to conventional kerosene flames, suggesting that MILD flames are thin fronts. MILD flames do not exhibit typical extinction behaviour, but gradually transition to a mixing solution at very high rates of strain (above A = 160, 000 s^?1 for all pressures). This is in agreement with literature that suggests heavily preheated and diluted flames have a monotonic S-shaped curve. Despite these differences in comparison with kerosene–air flames, MILD flames follow typical trends as a function of both strain and pressure. Further still, the peak locations of the overlap of OH and CH₂O mass fractions in comparison with the peak HRR indicate that the pixel-by-pixel product of OH- and CH₂O-PLIF signals is a valid experimental marker for non-premixed kerosene MILD and conventional flames.     

同步荧光光谱方法测定柴油中的溶剂油

同步荧光光谱方法与表面荧光技术结合,研究了柴油中混120#溶剂油的荧光光谱.通过佑发射峰位置蓝移程度可以快速分析出柴油中是否含有120#溶剂油,并发现含有120#溶剂油的柴油其发射峰相对纯柴油的发射峰偏移量与柴油中含有120#溶剂油的百分含量具有一定的关系.通过这种关系可以定性的判断出柴油中掺杂120#溶剂油的多少,这对于分析市场上柴油的真伪、维护市场稳定具有重要的意义.     

Raman Spectroscopy for the Undergraduate Teaching Laboratory: Quantification of Ethanol Concentration in Consumer Alcoholic Beverages and Qualitative Identification of Marine Diesels Using a Miniature Raman Spectrometer

Raman spectroscopy has steadily gained popularity as a powerful tool in both the analytical lab and the undergraduate classroom. The technique is attractive because it allows for rapid, nondestructive qualitative or quantitative analyses of many analytes with little or no sample preparation requirements. The introduction of less expensive, smaller, and more powerful diode laser excitation sources and the recent availability of rugged, red‐sensitive, charge‐coupled device–based miniature modular spectrometers has prompted the integration of Raman spectroscopy into the undergraduate curriculum. We have evaluated the analytical utility of a small, portable Raman instrument for the qualitative and quantitative analyses of two “real” samples. The experiments in this paper were designed to be used as a laboratory component for undergraduate education and include the quantification of ethanol in consumer alcoholic beverages and the qualitative identification of marine diesel fuels that had been spilled on surface waters. In the case of the liquor samples, the ethanol concentration in colorless, odorless alcoholic beverages could be determined very rapidly, but colored and heavily scented liquors proved more difficult and required pretreatment with activated carbon to remove fluorescence that masked the Raman signal. Similarly, a high‐intensity fluorescence background was observed to mask characteristic Raman bands of the diesel fuels. Some reduction in the intensity of the fluorescence was observed after carbon pretreatment of the fuels. The set of undergraduate experiments described in this paper treat the concepts of quantitative and qualitative analysis using portable instrumentation, instrumental calibration by the standard addition and external curve methods, and method development for the analysis of real consumer and environmental samples.     

A surrogate fuel for kerosene

Experimental and numerical studies are carried out to develop a surrogate that can reproduce selected aspects of combustion of kerosene. Jet fuels, in particular Jet-A1, Jet-A, and JP-8 are kerosene type fuels. Surrogate fuels are defined as mixtures of few hydrocarbon compounds with combustion characteristics similar to those of commercial fuels. A mixture of n-decane 80% and 1,2,4-trimethylbenzene 20% by weight, called the Aachen surrogate, is selected for consideration as a possible surrogate of kerosene. Experiments are carried out employing the counterflow configuration. The fuels tested are kerosene and the Aachen surrogate. Critical conditions of extinction, autoignition, and volume fraction of soot measured in laminar non premixed flows burning the Aachen surrogate are found to be similar to those in flames burning kerosene.A chemical-kinetic mechanism is developed to describe the combustion of the Aachen surrogate. This mechanism is assembled using previously developed chemical-kinetic mechanisms for the components: n-decane and 1,2,4-trimethylbenzene. Improvements are made to the previously developed chemical-kinetic mechanism for n-decane. The combined mechanisms are validated using experimental data obtained from shock tubes, rapid compression machines, jet stirred reactor, burner stabilized premixed flames, and a freely propagating premixed flame. Numerical calculations are performed using the chemical-kinetic mechanism for the Aachen surrogate. The calculated values of the critical conditions of autoignition and soot volume fraction agree well with experimental data. The present study shows that the chemical-kinetic mechanism for the Aachen surrogate can be employed to predict non premixed combustion of kerosene.     

几种常用油品拉曼光谱的检测及分析

采用拉曼光谱技术检测不同种类油品,探索汽油、柴油、石脑油等常用油品的拉曼光谱图的规律性。方法:利用自行研制的785nm激发波长便携式拉曼光谱仪检测150例种类不同的油品,并对这些油品的拉曼光谱图进行拉平及归一法处理。结果:汽油、柴油、石脑油、航煤这四大类油品的拉曼谱图具有各类的特点及规律,根据其中烯烃峰的拉曼位移及对应峰的强度可以对汽油及石脑油进行鉴别,并且可以筛查出一部分不合格汽油。利用拉曼光谱法检测不同种油品其操作简便,无需前处理,需要的样本量小,不同种油品的拉曼位移和强度上存在着差异,拉曼光谱法在建立油品现场快速筛查、检测及鉴别方法上具有很大潜力。     

Surrogate formulation for diesel and jet fuels using the minimalist functional group (MFG) approach

Surrogate fuels aim to reproduce real fuel combustion characteristics in order to enable predictive simulations and fuel/engine design. In this work, surrogate mixtures were formulated for three diesel fuels (Coryton Euro and Coryton US-2D certification grade and Saudi pump grade) and two jet fuels (POSF 4658 and POSF 4734) using the minimalist functional group (MFG) approach, a method recently developed and tested for gasoline fuels. The diesel and jet fuel surrogates were formulated by matching five important functional groups, while minimizing the surrogate components to two species. Another molecular parameter, called as branching index (BI), which denotes the degree of branching was also used as a matching criterion. The present works aims to test the ability of the MFG surrogate methodology for high molecular weight fuels (e.g., jet and diesel). ¹H Nuclear Magnetic Resonance (NMR) spectroscopy was used to analyze the composition of the groups in diesel fuels, and those in jet fuels were evaluated using the molecular data obtained from published literature. The MFG surrogates were experimentally evaluated in an ignition quality tester (IQT), wherein ignition delay times (IDT) and derived cetane number (DCN) were measured. Physical properties, namely, average molecular weight (AMW) and density, and thermochemical properties, namely, heat of combustion and H/C ratio were also compared. The results show that the MFG surrogates were able to reproduce the combustion properties of the above fuels, and we demonstrate that fewer species in surrogates can be as effective as more complex surrogates. We conclude that the MFG approach can radically simplify the surrogate formulation process, significantly reduce the cost and time associated with the development of chemical kinetic models, and facilitate surrogate testing.     

Cogeneration: One way to use biomass efficiently

Cogeneration in district heating systems is the most energy-efficient way to convert biomass into heat and electricity with current or nearly commercial technologies. Methanol produced from biomass and used in vehicles instead of petrol or diesel could reduce carbon dioxide emissions nearly as much per unit of biomass as if the biomass were used to replace natural gas for cogeneration, but at some higher cost per unit of carbon dioxide reduction. The most energy-efficient way to use biomass for cogeneration appears to be combined cycle technology, and the world's first demonstration plant is now being built. Potentially, this technology can be used for electricity production in Swedish district heating systems to provide nearly 20% of current Swedish electricity production, while simultaneously reducing carbon dioxide emissions from the district heating systems by some 55%. The heat costs from cogeneration with biomass are higher than the heat costs from fossil fuel plants at current fuel prices. Biomass can only compete with fossil fuels if other advantages, for example a lower environmental impact, are considered.     

基于拟Monte-Carlo方法测定油类混合物组分含量的研究

汽油、煤油、柴油是由原油加工而成,但其相应馏程特征有所不同,其中汽油的沸程约为35~205 ℃,煤油的沸程约为140~250 ℃,柴油的沸程约为180~370 ℃,同时,其碳链长度有所不同,汽油在C7～C11范围内,煤油在C12～C15范围内,柴油在C15～C18范围内,由于其碳数分布特征有所差异,其荧光光谱也相应有所差别,这是对三类不同油种进行识别与定量检测的基础。由于海洋时常发生油类污染,监测海洋中油类有机物的含量十分重要,采用拟Monte-Carlo方法计算三维荧光光谱特征峰幂次积分,结合最优算法求解最佳特征峰数量及积分区域范围,利用BFGS法解非线性方程组,提出一种光谱重叠的多种矿物油混合物组分含量测定的方法。由于对选定特征区域内确定点列对应峰值的幂次进行累加,对荧光谱线微小变化敏感,从而对组分含量微小变化敏感。同时由于点列的选取,相比于单点测量法,在一定程度上减小了随机误差的影响,可以进一步提高测量灵敏度。以煤油、柴油、汽油为研究对象,将单一油种视为整体,不考虑每种油的具体组分,测量单一油种及混合物的三维荧光光谱及等高线图谱,经最优算法选择六个特征峰进行特征峰幂次积分,测定混合油中组分含量,与峰值法,均值法等单点测量方法相比较,测量灵敏度提高约50倍,实现了混合物组分含量的高精度测量,为不需化学分离直接测定光谱重叠混合物组分含量提供了一种实用算法。     

三维荧光光谱及平行因子分析在石油类污染物检测分析中的应用

以三维荧光光谱技术结合平行因子分析算法研究了石油类污染物识别与浓度测量方法,重点分析了两种以上成品油共存时对测量的影响。以0#柴油、97#汽油与煤油的CCl4溶液为测量样本,通过两种或三种油不同配比的混合溶液来模拟多种石油类污染物共存的状态,研究平行因子分析方法在复杂混合物共存体系成分分析时的特点。实验分别针对汽柴油混合溶液、柴煤油混合溶液以及存在少量煤油干扰成分的汽柴油溶液,分解得到各溶质的激发与发射特征光谱,实现了各混合样品中主要成分含量的同时测量,计算了平均回收率。结果表明,该方法能够实现石油类污染物中共存成分的识别与浓度测量。     

三维荧光光谱差谱法测定柴油中的溶剂油

文章通过三维荧光光谱差谱技术研究了柴油中混有溶剂油的性质.这种技术可以快速分析出柴油中是否含有120#溶剂油,并对差谱后的三维谱进行体积分发现,总的体积与柴油中含有120#溶剂油的百分含量有一定的关系.这对于分析市场上柴油的真伪、维护市场稳定具有重要的意义.     

基于荧光光谱的五维数据处理方法

石油是一种成分复杂的混合物,通过常规的检测方法很难对其进行定性识别。本文用汽、煤、柴油的混合物来模拟环境中的油类污染物。汽、煤、柴油在特定波长范围的激发下可以发出含有物质自身信息的荧光,根据朗伯-比尔定律可知荧光强度与物质浓度成正比,利用该性质对特定物质进行识别。通过FS920稳态荧光光谱仪对样本进行测量,将实验所得的三维数据拓展为五维数据,提出了一种将展开偏最小二乘耦合到残差四线性的五维数据处理方法,同时采用五维平行因子法和该算法分解数据,实现了对汽、煤油的定量分析,并恢复出了其激发和发射光谱。结果表明,展开偏最小二乘法的分析效果更好。     

Laser metrology — a diagnostic tool in automotive development processes

Laser measurement techniques are widely used in automotive development processes. Applications at Volkswagen are presented where laser metrology works as a diagnostic tool for analysing and optimising complex coupled processes inside and between automotive components and structures such as the reduction of a vehicle's interior or outer acoustic noise, including brake noise, and the combustion analysis for diesel and gasoline engines to further reduce fuel consumption and pollution. Pulsed electronic speckle pattern interferometry (ESPI) and holographic interferometry are used for analysing the knocking behaviour of modern engines and for correct positioning of knocking sensors. Holographic interferometry shows up the vibrational behaviour of brake components and their interaction during braking, and allows optimisation for noise-free brake systems. Scanning laser vibrometry analyses structure-born noise of a whole car body for the optimisation of its interior acoustical behaviour.Modern engine combustion concepts such as in direct-injection (DI) gasoline and diesel engines benefit from laser diagnostic tools which permit deeper insight into the in-cylinder processes such as flow generation, fuel injection and spray formation, atomisation and mixing, ignition and combustion, and formation and reduction of pollutants. The necessary optical access inside a cylinder is realised by so-called ‘transparent engines’ allowing measurements nearly during the whole engine cycle. Measurement techniques and results on double-pulse particle image velocimetry (PIV) with a frequency-doubled YAG laser for in-cylinder flow analysis are presented, as well as Mie-scattering on droplets using a copper vapour laser combined with high-speed filming, and laser-induced fluorescence (LIF) with an excimer laser for spray and fuel vapour analysis.     

生物柴油发动机非常规排放的FTIR检测

采用傅里叶变换红外光谱FTIR,研究了汽车发动机燃用生物柴油的非常规排放物。所用燃料分别为纯柴油、纯生物柴油、生物柴油掺混比为20%的B20混合燃料。结果表明,该机燃用纯柴油和B20燃油的甲醛排放差别不大,纯生物柴油的甲醛排放则明显高于柴油。燃用B20燃油的乙醛排放略低于纯柴油;纯生物柴油的乙醛排放在中低负荷低于纯柴油,在高负荷时高于柴油及B20燃油。燃用B20燃油和纯生物柴油的丙酮排放要高于柴油,但排放量均较低。随着生物柴油掺混比例的增加,发动机甲苯和二氧化硫均呈逐渐下降趋势,纯生物柴油的二氧化硫排放大幅降低。燃用生物柴油后,发动机的二氧化碳排放有所降低,表明了生物柴油有利于温室气体的控制。     

基于近红外光谱法的多组分复杂溢油源定量建模分析

研究利用近红外光谱分析方法进行模拟复杂混合溢油源的定量分析问题。选取汽油、柴油、煤油三种轻质石油类产品,按照不同浓度比例配置成40个模拟混合溢油样本,利用傅里叶变换近红外光谱仪采集其在4 000～12 000 cm-1谱区范围内的近红外光谱;采用不同预处理方法,利用偏最小二乘算法建立混合溢油样本三组分各自的浓度定量模型。汽油、柴油和煤油的最优预处理方法均为二阶导数方法,分别在8 501.3～7 999.8 cm-1,6 102.1～4 597.8 cm-1,6 549.5～4 597.8 cm-1,7 999.8～7 498.4 cm-1和6 102.1～4 597.8 cm-1谱区范围内,预测模型的决定系数R2分别为0.998 2,0.990 2和0.993 6;RMSEP值分别为0.474 7,0.936 1和1.013 1;RPD值分别为25.126 9,10.517 3和13.072 0。实验结果表明：利用近红外光谱分析技术结合化学计量学方法能够定量确定模拟混合溢油样本中各组分的浓度,为海洋复杂溢油源的定量检测与分析提供有效手段。     

DMM及纳米颗粒添加剂对农用柴油机燃烧与排放性能的影响

本文通过在柴油中添加小比例二甲氧基甲烷(DMM)以及纳米氧化铝(Al2O3)颗粒研究一台小型农用柴油机的燃烧与排放特性。研究表明,随着柴油中DMM添加比例的增大,发动机燃烧特性参数如缸内压力、燃烧放热率及制动热效率得到明显地提升,着火延迟期以及CA50逐渐减小;排放方面HC和NOx增加,而CO和碳烟得到有效地抑制。燃油中同时添加DMM和纳米Al2O3颗粒后,发动机燃烧及排放方面得到了不同程度地优化。因此,将DMM与纳米颗粒的有机结合可为代用燃料在农用发动机中的推广应用提供新的思路。