Preparation and emission characteristics of ethanol-diesel fuel blends

The preparation of ethanol-diesel fuel blends and their emission characteristics were investigated. Results showed the absolute ethanol can dissolve in diesel fuel at an arbitrary ratio and a small quantity of water(0.2%) addition can lead to the phase separation of blends. An organic additive was synthesized and it can develop the ability of resistance to water and maintain the stability of ethanol-diesel-trace amounts of water system. The emission characteristics of 10%, 20%, and 30% ethanol-diesel fuel blends, with or without additives, were compared with those of diesel fuel in a direct injection(DI) diesel engine. The experimental results indicated that the blend of ethanol with diesel fuel significantly reduced the concentrations of smoke, hydrocarbon(HC), and carbon monoxide(CO) in exhaust gas. Using 20% ethanol-diesel fuel blend with the additive of 2% of the total volume, the optimum mixing ratio was achieved, at which the bench diesel engine testing showed a significant decrease in exhaust gas. Bosch smoke number was reduced by 55%, HC emission by 70%, and CO emission by 45%, at 13 kW/1540 r/min. However, ethanol-diesel fuel blends produced a few ppm acetaldehydes and more ethanol in exhaust gas.

Comparative Study of Performances of a Single-Cylinder Diesel Enginefueled with Pure Diesel and Blends of Biodiesels/Pure Diesel

In this study, the principal objective is to compare the performances of an air-cooled one cylinder, four-stroke direct injection diesel engine using the blends (5% by volume B5, 10% by volume B10) of diesel and biodiesels derived respectively from palm oil, castor oil and raphia sese De Wild oil with pure diesel. All the biodiesels used in this work come from the plant species of the democratic republic of Congo as listed above. The engine performances (power, torque and brake specific consumption) at different engine speeds were determined at both full and partial loads. According to experimental results, the increments in the power output and torque when the mixtures of diesel and biodiesels were used and were observed. On the other side, the specific fuel consumption of the mixtures is higher than that of pure diesel although the calculated lower heating values are almost within the same range for the all studied fuels. Finally, in partial load 1/1, pure diesel blended with biodiesels B5 derived from castor oil presented high specific brake consumption values compared to the other fuels while B10 from the same oil presents low brake specific consumption values for power greater than 3.2 kW.

Performance Evaluation of Spark Ignited Engine Fueled with Gasoline-Ethanol-Methanol Blends

In this paper, experimental investigations are presented to assess the performance variations in a single cylinder spark ignited engine when run with three different gasoline-alcohol blends： （88% gasoline-12% methanol, 88% gasoline-12% ethanol and 88% gasoline-6% methanol-6% ethanol）. Additional tests are carried out with the basic gasoline fuel for comparison analysis and performance assessment. Engine performance is investigated under a variety of engine operating conditions. The results are presented in the domain of engine speed. In particular, the brake power of the engine is shown to be slightly increased. The brake thermal efficiency showed an increase compared with the basic gasoline engine. Similarly, it is shown that brake specific fuel consumption is enhanced compared with basic gasoline engine. The exhaust gas temperature showed a decrease compared with gasoline fuel which is preferable to reduce emissions. The alcohol additives are strongly recommended to enhance performance, increasing the mileage and reducing the emissions.

Diesel molecular composition and blending modeling based on SUBEM framework

Diesel molecular compositional model has important application for diesel quality prediction,blending,and molecular-level process model development.In this paper,different types of diesel molecular compositional and blending models were constructed based on the SU-BEM framework.More than 1500 representative molecules were selected to form the molecular structure library.The probability density functions(PDFs)combination was determined by experimental data and experience.A quadratic optimization strategy combining genetic algorithm with local optimization algorithm was adopted to improve the accuracy of the compositional model.The model results show good agreement with the experimental data.The diesel blending model was constructed at the molecular-level based on the above diesel compositional models.The properties of the blending model accord with the experimental regulations.It is proved that the compositional models and blending model constructed have high accuracy and strong prediction capability,and are applicable to the industrial process.

Dispersion Performance of Methanol-Diesel Emulsified Fuel Prepared by High Gravity Technology

A new continuous process for preparing methanol-diesel emulsified fuel with an Impinging Stream-Rotating Packed Bed is proposed. The droplet size of dispersed phase(methanol) of the emulsified fuel has a significant effect on the combustion of methanol-diesel emulsified fuel. In this paper, the methanol-diesel emulsified fuel uses diesel as the continuous phase and methanol as the dispersed phase. The Sauter mean diameter of the dispersed phase of methanol-diesel emulsified fuel was characterized with microphotography and arithmetic method. The experimental result showed that the Sauter mean diameter of the dispersed phase, which was decreased with the augmentation of the high gravity factor, liquid flow rate and emulsifier dosage, was inversely proportional to the methanol content. The Sauter mean diameter of the dispersed phase can be controlled and adjusted in the range of 12—40 μm through the change of operating conditions. The correlative expressions of the Sauter mean diameter of emulsified fuel were obtained and the calculated values agreed well with the experimental values.

Experimental Study on Performance and Combustion Analysis of a Diesel Engine Fueled with Diesel and Jatropha Oil Blended with Heptane

This work focuses on blending Jatropha oil with diesel fuel and heptane to improve its physico-chemical characteristics for production of blends and their use as fuel in a diesel engine. The influence of the heptane content was evaluated by comparing the results obtained from the engine (performance and combustion parameters) with those of the diesel fuel and straight Jatropha oil. The results obtained show an improvement in engine performance especially at low loads. Specifically, a reduction in the specific fuel consumption of the engine is obtained when the heptane content in the mixture is around 10% compared to that obtained with pure Jatropha oil. The best results were obtained with the blend containing 70% Jatropha oil, 20% diesel fuel and 10% heptane (J70G20H10). Overall engine efficiency and exhaust gas temperatures are comparable for all fuels tested. Engine combustion parameters are improved with J70G20H10. The results obtained with J70G20H10 are close to those of the engine operating on diesel fuel. The cyclic dispersion is low with coefficients of variation of the indicated mean effective pressure (COVIMEP) whose values are less than 10%. The lowest values of the COVIMEP are obtained with the blend J70G20H10.

Experimental Study on the Performance and Emission of Chinese Small Agricultural Diesel Engine Fuelled with Methanol/Biodiesel/DTBP

Diesel engine alternative fuels, such as methanol and biodiesel, are beneficial to reduce diesel engine emission. In order to study the influence of methanol and biodiesel on the performance, economy and emission of small agricultural diesel engine, the physical-chemical properties(cetane number, lower heat value(LHV), viscosity, etc.) of methanol and biodiesel were analyzed. The methanol and biodiesel showed good complementary property to some extent. When a large proportion of methanol was added into biodiesel, the cetane number of the methanol/biodiesel blend will be greatly reduced. Since the cetane number of the blend fuel has great influence on the combustion process of diesel engine, after testing for blending ratio of methanol/biodiesel, the blend was prepared with 5%(BM5), 10%(BM10) and 15%(BM15) methanol, respectively. Di-Tert-Butyl Peroxide(DTBP) was chosen as a cetane number improver to be added into methanol/biodiesel blend. 0.25%, 0.50% and 0.75% of DTBP was added into BM15. The bench test was carried out on a 186 FA diesel engine to study the effect of methanol and DTBP on the engine performance and emissions. The results show that, at rated condition, compared with biodiesel, the NO;concentration of BM5, BM10 and BM15 is reduced by 5.02%, 33.85% and 21.24%, and smoke is reduced by 5.56%, 22.22% and 55.56%. However, the engine power is also reduced by 5.77%, 14.23% and 25.41%, and the brake specific energy consumption is increased by 3.31%, 7.78% and 6.37%. The addition of DTBP in methanol/biodiesel could recover the engine power to the level of diesel. DTBP shows good effect on the reduction of the brake specific energy consumption and NO_(x), CO, HC concentration, but a little increase of exhaust smoke.

Effect of <i>γ</i>-Valerolactone Blending on Engine Performance, Combustion Characteristics and Exhaust Emissions in a Diesel Engine

γ-valerolactone (GVL) is a C5-cyclic ester that can be produced from biomass providing a potentially renewable fuel for transportation and feedstock for the chemical industry. Experiments were performed with fossil diesel (D), D + biodiesel (BD) and D + BD + GVL blends. A four-cylinder, turbocharged direct injection diesel engine was used for the tests. The engine was coupled to a dynamometer to vary the load. CO, NOx, THC and smoke emissions were measured by using a multi-channel gas analyzer. Combustion characteristics were assessed by in-cylinder pressure data with respect to crank angle and the derived heat release rates. Compared with D, and D + BD blends, addition of GVL had relatively little effect on engine performance and NOx emission, but reduced the exhaust concentration of CO, unburned fuel and smoke significantly. The smoke reduction is particularly notable in view of the very recent suggestion that black carbon is the second most important greenhouse gas in the atmosphere next to carbon dioxide. No diesel engine study with GVL has been reported so far.

1,1-Dibutoxybutane as a Petroleum Diesel Fuel BlendingComponent and Their Mixture Performance

Effect of 1,1-dibutoxybutane （DBB） addition on petroleum DF （diesel fuel） performance has been studied. The study wasstarted by preparing DBB from decomposition of 1 -butanol on manganese impregnated on activated carbon （Mn/AC） catalyst at 450 ℃ in stainless steel reactor. The product was distilled at 200 ℃ and the residue obtained was analyzed by GC-MS and HSQC NMR toconfirm its structure and purity. The DBB-DF mixtures were prepared at different compositions and determined their excess molarvolume, homogeneity, phase stability, ignition quality, lubricity, cold flow quality, energy content, and viscosity. The addition of DBBinto DF formed a homogeneous mixture and had a good phase stability. The mixtures gave positive excess molar volume values overthe whole concentration ranges. The ignition quality and lubricity of the mixtures increased without lost in cold flow quality. Slightdecreased in viscosity and energy content per mass unit were observed.

乳化剂对甲醇柴油液滴蒸发微爆特性的影响

乳化燃油微爆能够促进燃油雾化和混合,影响其微爆性能的关键是乳化剂。文章采用机械搅拌加超声搅拌法制备了微乳化甲醇柴油,研究了乳化剂种类和含量对微乳化甲醇柴油稳定性和分散性的影响规律。研究结果表明:采用复合乳化剂和增加乳化剂含量均能提高微乳化甲醇柴油的分散性;增加乳化剂含量能够提高液滴微爆强度,推迟初次微爆时刻,减少液滴寿命,降低稳定阶段的液滴蒸发速率;当甲醇和乳化剂的质量比为10∶5和10∶8时,液滴微爆强度分别比甲醇和乳化剂质量比为10∶3时提高了34.3%和37.6%。

OP2S双燃料发动机气口匹配特性研究

对置活塞二冲程(OP2S)发动机是一种结构可调性较高的动力系统,采用等效二冲程方法建立并校验了OP2S柴油机的一维仿真模型,研究了不同甲醇含量下进排气口高度冲程比对OP2S柴油机动力性能、燃油经济性、换气性能和排放性能的影响。结果表明:OP2S柴油机具有换气性能和排放性能的双“trade-off”关系。甲醇含量增加会促进经济性能的提高和动力性能的降低,也会促进扫气效率的增加和捕获率的降低。进排气口的匹配设计是提升OP2S柴油机性能的关键之一。进气口通过增加新鲜空气主动促进燃烧,而排气口通过减少能量和新鲜充量损失被动改善换气性能。随着气口高度的增加,OP2S柴油机的性能曲线具有双转捩点。将性能曲线分为3个区域,其中第2区域为最佳性能区,该区域对应的进/排气口高冲程比分别为0.056~0.122和0.078~0.100。

利用SE-GPR模型对甲醇/柴油混合燃料柴油机性能的预测

为了对柴油机的经济性和排放参数进行高效、准确的预测,根据4190型船用柴油机实验数据与边界参数,建立AVL-BOOST甲醇/柴油混合燃料柴油机仿真模型;利用模型进行仿真实验,并建立甲醇掺混比、废气再循环(exhaust gas recirculation,EGR)率、喷油提前角和进气压力4个控制参数对有效油耗率和NO x排放预测数据集;利用该数据集对5种不同核函数的高斯过程回归(Gaussian process regression,GPR)模型进行训练;最后将最优的平方指数高斯过程回归(squared exponential-Gaussian process regression,SE-GPR)模型、AVL-BOOST仿真数据和柴油机实验数据进行对比。结果表明:在数据量为180组时,SE-GPR模型对有效油耗率和NO x排放均取得拟合关联度99%以上,均方根误差(root mean square error,RMSE)分别为1.859,0.3445,平均绝对误差(mean absolute error,MAE)分别为0.954,0.2489;并且,相较于AVL-BOOST仿真实验,SE-GPR模型对实验数据具有更好的拟合性。

不同海拔下甲醇替代率和主喷正时对RCCI发动机性能的影响

为探究不同海拔条件下甲醇/柴油反应活性控制压燃(reactivity controlled compression ignition, RCCI)发动机的运行特性,该研究基于甲醇/柴油双燃料发动机试验台架,试验研究1 800 r/min、100%负荷和3 200 r/min、100%负荷下不同甲醇替代率、柴油喷射正时对发动机燃烧与排放性能的影响规律。结果表明:不同海拔条件下随着甲醇替代率的增加,缸压和瞬时放热率峰值逐渐升高,燃烧始点和燃烧中心前移,当量有效燃油消耗率(equivalent brake specific fuel consumption, ESFC)降低,有效热效率升高,NO_x和碳烟排放大幅降低,THC(total hydrocarbons)和CO排放增加。1 800 r/min、100%负荷工况下,甲醇替代率由0增至20%,0、1 000、2 000 m海拔下最大缸压平均增加1.72 MPa,瞬时放热率峰值平均升高25.08 J/(°),ESFC平均降低4.67%,有效热效率平均升高4.90%,NO_x和碳烟排放分别平均降低16.63%和50%,THC和CO排放量分别平均增加142.03、388.18 mg/kg。3 200 r/min下甲醇替代率由0增至7%,不同海拔高度下ESFC平均降低1.76%,有效热效率平均升高1.79%,NO_x和碳烟排放量分别平均降低8.17%和20.70%。海拔高度由0升至2 000 m,1 800 r/min、20%甲醇替代率与3 200 r/min、7%甲醇替代率下,瞬时放热率峰值分别降低4.80和8.08 J/(°),燃烧中心分别推迟1.44°和1.43°,有效热效率分别降低0.82%和0.68%,ESFC分别升高2.10%和1.99%,NO_(x)排放量分别减少10.61%和7.35%,碳烟排放分别增加26.54%和32.12%,THC排放分别升高29.88%和15.45%,CO排放量分别增加22.42%和18.15%。固定甲醇替代率后,随着柴油主喷正时提前,不同海拔条件下缸压和放热率峰值逐渐升高,燃烧中心向上止点靠近,ESFC逐渐降低,有效热效率升高,碳烟排放减少,NO_(x)、THC和CO排放增加。1 800 r/min、15%甲醇替代率下,主喷正时从-1.5°提前至-7.5°,不同海拔高度下ESFC平均降低8.27%,有效热效率平均升高9.08%,碳烟排放平均减少90.94%。为提升高海拔条件下甲醇/柴油RCCI发动机的热效率和燃油经济性,可以适当增大柴油主喷正时。研究结果可为不同海拔环境下甲醇/柴油RCCI发动机燃烧与污染物排放控制优化提供参考。

煤基燃料燃烧颗粒物对颗粒捕集器沉积过程的影响

探讨了柴油机燃用代用燃料后,排气颗粒物结构特征的变化规律。依据柴油机台架试验,使用0%、5%、15%甲醇掺混比的F-T(Fischer–Tropsch)合成柴油,在标定工况下采集颗粒。用同步辐射小角散射分析方法测量颗粒物摩擦力、粒径等参数。基于实验数据,在EDEM软件中建立颗粒模型,模拟了颗粒碰撞沉积过程。结果表明:随甲醇掺混比的增加,甲醇、F-T柴油燃烧颗粒间摩擦力增加0.6 N,平均粒径增加2.44 nm。沉积过程中,颗粒捕集器(DPF)单元体非迎风面的沉积量急剧增加;颗粒沉积效率随沉积时间的增加而增加;随摩擦力增大、粒径增大,颗粒层厚度及颗粒链长度也随之增加。甲醇掺混比的改变使得颗粒整体向更多、更细的方向变化,燃料类型及掺混比的改变显著影响了颗粒在DPF载体上的沉积状态。

掺混策略对聚甲氧基二甲醚/甲醇双燃料燃烧影响的可视化研究

基于一台单缸光学发动机,采用高速摄影和瞬态压力同步测量方法,开展了不同掺混策略对聚甲氧基二甲醚(polyoxymethylene dimethyl ethers,PODE)/甲醇双燃料燃烧及火焰发展特性的影响研究,其中掺混策略包括P/M20(甲醇和PODE以2∶8的体积比掺混)燃料双喷射模式和缸内直喷PODE引燃预混甲醇混合气的反应活性控制压燃(reactivity-controlled compression ignition,RCCI)模式。结果表明,对于P/M20燃料双喷射模式,随着气道喷射比例增加,低温反应增强,滞燃期缩短,着火时刻显著提前,进而显著改善了燃烧稳定性;对于RCCI模式,随着气道喷射甲醇占比的增加,滞燃期延长,燃烧相位推迟,峰值压力和放热率均降低,并伴随着燃烧稳定性变差。燃烧可视化显示,两种掺混策略下,随着气道喷射比例的增加,蓝色预混火焰占比增大,最大火焰传播速度降低,由于末端未燃混合气浓度增加,火焰发展由明显的扩散燃烧逐渐转变为末端混合气不断出现新自燃点的顺序自燃模式。对比两种掺混策略可以发现,推迟缸内直喷时刻均能在一定程度上优化燃烧相位,显著改善指示热效率,然而其原因侧重点不同:对于P/M20燃料双喷射模式,提高气道喷射比例可以增强低温放热,促进着火,显著改善燃烧稳定性;对于RCCI模式,其燃烧过程主要位于上止点之后,燃烧相位更接近最佳燃烧相位,进一步减小了传热损失和循环负功,因此其具有更高的指示热效率,也更适合PODE/甲醇双燃料燃烧模式。

同牌号油品不同密度差值范围对油品调和影响的探讨

通过实验室模拟试验和石油库油罐混调试验,分别对汽油和柴油的不同密度差值范围的油品混调时呈现的分层现象进行了试验和分析,结果表明:随着密度差值范围的增大,油品的相溶区域在不断收缩变窄,相溶区域内的密度差幅度也在增大,密度分布分层现象也越来越严重。汽油组的硫含量和辛烷值指标数据以及柴油组的硫含量和闪点指标数据都是同步随着油品混合状态进行分布。为此,建议成品油销售企业制定调和方案时:油品密度差值范围在0~2kg/m^(3)时,大部分的混合区域能呈现混溶状态,可进行调和;密度差值范围在2~4kg/m^(3)时,相溶区域逐渐缩减,分层趋势逐渐显现,可进行调和,但需将管控等级设为中风险级,应做好调和后的取样监测工作;密度差值范围大于4kg/m^(3)后,相溶区域集中在油品交界区域内,已呈现明显的分层现象,管控等级为高风险级,不建议进行调和。

进气参数对柴油引燃的甲醇发动机性能影响

进气温度及进气压力对缸内燃烧效果和传热传质效果有很大的影响,进而影响柴油机的动力特性和排放特性,为此本文开展了进气参数对柴油引燃的甲醇发动机燃烧和排放性能的影响研究。研究表明,与原机进气压力1.91 bar相比,进气压力在2.31 bar时,柴油机缸内最大爆发压力升高14.3%,CO最终排放量下降66.3%,soot最终排放量升高20.8%,NOx最终排放量下降2.8%。较原机进气温度380 K相比,进气温度在420 K时,缸内最大爆发压力下降4.2%,CO最终排放量升高2.3倍,soot最终排放量升高15.7%,NOx最终排放量升高19.4%。2种进气参数的组合可以给柴油机带来更高的动力性和更好的排放性能。研究结果表明,适当的调整进气压力和进气温度可以改善柴油引燃的甲醇发动机的动力性能和排放性能。

甲醇替代率对两段喷射F-T柴油/甲醇双燃料发动机排放的影响

以一台高压共轨柴油机为基础,在进气歧管处加装甲醇喷射系统,同时缸内两段直喷(预喷+主喷)煤制费托合成柴油(F-T柴油),搭建F-T柴油/甲醇(F/M)双燃料发动机试验台架,在转速为2 000 r/min,负荷为25%,50%,75%和100%的工况下分别探究甲醇替代率对发动机排放性能的影响,同时为实现F-T柴油/甲醇反应活性控制压燃模式探寻理论基础。研究结果表明:在中高负荷下,F/M双燃料发动机的燃油经济性较好;与单燃料压燃模式相比,F/M双燃料燃烧模式的HC,CO,Soot,甲醇和甲醛排放量均有所增加,且随着甲醇替代率的增大而增加,随着负荷的升高而下降;CO_(2),NO_(x)和NO的排放量随着甲醇替代率的增大而减小,随着负荷的升高而增加;NO_(2)的排放量随着甲醇替代率和负荷的增大而增加。

燃煤锅炉点火系统甲醇替代柴油改造探析

介绍了燃煤锅炉几种常用的点火方式。针对长青能化公司3台燃煤锅炉柴油点火及稳燃系统存在的点火和稳燃过程中油雾燃烧不完全、排放黑烟、尾部除尘器布袋阻力大等问题,利用自产清洁绿色甲醇替代柴油作为燃料,对柴油点火及稳燃系统进行了改造。改造后彻底解决了上述问题,还可节约48%的燃料费用。此外,还解决了甲醇点火及稳燃系统出现的新问题。

催化裂化装置掺炼直馏柴油效果分析

针对催化裂化装置掺炼直馏柴油进行了分析。某石化公司在降低柴汽比过程中,2套催化裂化装置掺炼了常减压装置10%的直馏重柴油,在确保质量合格及操作参数没有大幅度变化的情况下,2套催化装置汽油收率提高了0.5%~3%,液化气收率提高了0.3%~1%,柴油收率降低了0.5%~2.5%,明显降低了柴汽比,为后续装置进行直馏柴油掺炼累部分操作经验,同时为全厂降低柴汽比积累了数据。