The Effect of Lateral Offset Distance on the Aerodynamics and Fuel Economy of Vehicle Queues

The vehicle industry is always in search of breakthrough energy-saving and emission-reduction technologies.In recent years,vehicle intelligence has progressed considerably,and researchers are currently trying to take advantage of these developments.Here we consider the case of many vehicles forming a queue,i.e.,vehicles traveling at a predetermined speed and distance apart.While the majority of existing studies on this subject have focused on the influence of the longitudinal vehicle spacing,vehicle speed,and the number of vehicles on aerodynamic drag and fuel economy,this study considers the lateral offset distance of the vehicle queue.The group fuel consumption savings rate is calculated and analyzed.As also demonstrated by experimental results,some aerodynamic benefits exist.Moreover,the fuel consumption saving rate of the vehicle queue decreases as the lateral offset distance increases.

Engine performance and combustion characteristics of a direct injection compression ignition engine fueled waste cooking oil synthetic diesel

Biodiesels produced from various feedstocks have been considered as alternative fuels used in internal combustion engines without major modifications.This research focuses on producing biodiesel from waste cooking oil(WCOSD)by the catalytic cracking method using MgO as the catalyst and comparing the engine operating characteristics of the test engine when using WCOSD and traditional diesel(CD)as test fuels.As a result,the brake power of the test engine fueled WCOSD,and traditional diesel is similar.However,the engine fuel consumption in the case of using WCOSD is slight increases in some operating conditions.Also,the nitrogen oxides emissions of the test engine fueled WCOSD are higher than those of CD at all tested conditions.The trend is opposite for hydrocarbon emission as the HC emission of the engine fueled by WCOSD reduces 26.3%on average.The smoke emission of the test engine in case of using WCOSD is lower 17%on average than that of CD.However,the carbon monoxide emissions are lower at the low and medium loads and higher at the full loads.These results show that the new biodiesel has the same characteristics as those of commercial biodiesel and can be used as fuel for diesel engines.

Evaluation of a Pulse Width Modulated Bypass Nozzle for the Development of a Variable Load Residential Oil Burner

Due to the need for energy conservation in buildings and the simultaneous benefit of cost savings, the development of a low firing rate load modulating residential oil burner is very desirable. One of the two main requirements of such a burner is the development of a burner nozzle that is able to maintain the particle size distribution of the fuel spray in the desirable (small) size range for efficient and stable combustion. The other being the ability to vary the air flow rate and air distribution around the fuel nozzle in the burner for optimal combustion at the current fuel firing rate. In this paper, which deals with the first requirement, we show that by using pulse width modulation in the bypass channel of a commercial off-the-shelf bypass nozzle, this objective can be met. Here we present results of spray patterns and particle size distribution for a range of fuel firing rates. The results show that a desirable fuel spray pattern can be maintained over a fuel firing rate turndown ratio (Maximum Fuel Flow Rate/Minimum Fuel Flow Rate) of 3.7. Thus here we successfully demonstrate the ability to electronically vary the fuel firing rate by more than a factor of 3 while simultaneously maintaining good atomization.

How Much Fossil Fuel Is in the Earth?

In this work, by using an indirect method based on the correspondence between the amount of oxygen in the atmosphere and the quantity of fossil fuel in the Earth, the resources of fossil fuels were evaluated to be about 1.9 × 1016 ton. Unluckily, only a small part of these fuels is easily accessible. Nevertheless, their quantity is so high that it is reasonable to assume that fossil fuels will continue to dominate the global energy scene for several years. The extensive use of fossil fuels alters the ratio between oxygen and carbon dioxide in the atmosphere. The effects of this change are however so slow that they become important only on the geological time scale.

Thermodynamic Performance Analysis of a Gas Turbine in an Equatorial Rain Forest Environment

This paper discusses the thermodynamic analysis of a gas turbine power plant located in the equatorial rainforest of southern Nigeria. Steady state monitoring and direct collection of data from the Mk IV Speedtronics system and log books in the control room was performed. The variation of operating conditions (ambient temperature, compressor discharge temperature, turbine inlet temperature, exhaust temperature and fuel mass flow rate) on the performance of gas turbine (thermal efficiency, net power output, heat rate, specific fuel consumption and compressor work) were investigated using various thermodynamic relations and equations. The results show that a degree rise in ambient temperature could be responsible for the following: 1.37% reduction in the net power output, 1.48% increase in power drop, 1.49% reduction in thermal efficiency, 2.16% increase in heat rate, 2.17% increase in specific fuel consumption and 0.3% increase in compressor work. Furthermore the thermal efficiency decreases by 0.006% for 1 kcal/kWh increase in heat rate and the heat transfer in the hot gas part was found to increase by 0.16% for a degree rise in ambient temperature. Also the work reveals that the gas turbine had a huge drop in power due to influence of site parameters in contrast to designed data.

Investigating the effects of gradual deployment of market penetration rates(MPR)of connected vehicles on delay time and fuel consumption

Purpose–This research paper aims to investigate the effects of gradual deployment of market penetration rates(MPR)of connected vehicles(MPR of CVs)on delay time and fuel consumption.Design/methodology/approach–A real-world origin-destination demand matrix survey was conducted in Boston,MA to identify the number of peak hour passing vehicles in the case study.Findings–The results showed that as the number of CVs(MPR)in the network increases,the total delay time decreases by an average of 14%and the fuel consumption decreases by an average of 56%,respectively,from scenarios 3 to 15 compared to scenario 2.Research limitations/implications–The first limitation of this study was considering a small network.The considered network shows a small part of the case study.Originality/value–This study can be a milestone for future research regarding gradual deployment of CVs’effects on transport networks.Efficient policy(s)may define based on the results of this network for Brockton transport network.

Using Less Oil Despite the unquenchable thirst for oil to fuel nina's fast growing economy,the oil consumption growth rate is dropping

At first glance, the official figures of China's oil consumption in 2005 seem a bit confusing. With a robust economic growth and rising annual oil imports, China made the surprise announcement that its oil consumption growth rate was dropping sharply, from 15.3 percent in 2004 to 2.1 percent in 2005. Earlier, China's Ministry

An Assessment of Eco Driving System for Agricultural Tractor

In this study, tractor power output, fuel consumption rate and work performance were indirectly predicted in order to develop an eco driving system. Firstly, equations were developed which could foretell tractor power output and fuel consumption rate using characteristic curves of tractor power output. Secondly, with actual engine revolution per minute （rpm） determined by initial engine rpm and work load, tractor power output and fuel consumption rate were forecasted. Thirdly, it was possible to foresee tractor work performance and fuel consumption rate by the speed signals of Global Positioning System （GPS）. Lastly, precision of the eco driving system was evaluated through tractor Power Take-Off （PTO） test, and effects of the eco driving system were investigated in the plowing and rotary tilling operations. Engine rpm, power output, fuel consumption rate, work performance and fuel consumption rate per plot area were displayed on the eco driving system. Predicted tractor power outputs in the full load curve were well coincided with the actual power output of prototype, but small differences, 1 to 6 kW were found in the part load curve. Error of the fuel consumption rate was 0.5 to 3 L/h at the part load curve. It was shown that 69% and 53% of fuel consumption rates could be reduced in plowing and rotary tilling operations, respectively, when the eco driving system was installed in tractor.

高性能机油净化碳基复合定型滤芯研制与应用

针对目前机油滤清器滤芯存在的机油净化性能差、使用寿命短等问题,通过活性炭与聚氨酯经插嵌微发泡复合定型,研发首创出具有开孔型微泡网状结构碳基复合定型滤芯,并研究其性能。结果表明,碳基复合定型滤芯属于过滤-吸附双效深层体型滤材,阻力小、流量大;通过开孔型微泡网状结构过滤作用和碳材料吸附作用的协同效应,显著提升机油净化性能、延长使用寿命;与德国马勒纸质滤清器相比,碳基复合滤清器在汽车90 km/h等速行驶测试中节约燃油达3.80%,4辆实车、累计66801公里行驶验证,碳基复合滤清器节约燃油3.17~3.33%。碳基复合滤清器节油效果显著,大规模推广与应用将产生巨大的经济效益和社会效益。

重型柴油机二级增压系统匹配仿真研究

为了降低重型柴油机的燃油消耗率,采用GT-POWER软件建立仿真模型,在一台单级可变截面涡轮增压器(variable geometry turbocharger,VGT)柴油机上开展了二级增压匹配与增压系统参数优化工作。仿真结果表明,所提出的二级增压系统在匹配点能够以最高效率运行,在全工况都能提供足够的进气流量;完全关闭低压级废气旁通阀,正交优化高压级废气旁通阀开度和米勒循环度,能够进一步降低二级增压发动机的燃油消耗率;降低级间中冷温度能够降低泵气损失,提高增压压力,温度由100℃降至50℃在标定点能够使燃油消耗率降低约3 g/(kW·h)。对二级增压及参数优化工作的燃油消耗率改善效果进行了试验验证,低速工况燃油消耗率整体有所下降,高效点燃油消耗率下降4.1%。

结构对耗氧型惰化系统中反应器性能的影响

针对新型低温催化惰化系统中反应器存在的易飞温和转化率低的问题,基于FLUENT多孔介质模型,以用户自定义标量(UDS)添加固相能量方程,以用户自定义函数(UDF)形式加入化学反应,建立了圆柱体、圆锥体及反圆锥体3种结构的反应器仿真模型,并通过自建试验台对模型的正确性进行了验证。定义了转化率和耗氧速率2个性能指标,研究了反应器进口气体温度、进口流量和RP-3燃油蒸气体积浓度对反应器性能的影响,分析了反应器的操作范围,并从流动速度的角度出发,比较了3种结构反应器的性能差异。结果表明:进口气体的温度及RP-3燃油体积浓度的提高以及进口流量的减小可以促进反应的发生;反应器的起燃温度为470 K;在相同条件下,3种结构反应器的转化率从高到低依次为圆锥体、圆柱体、反圆锥体,可操作温度范围差值为8~10 K。

涡轮电力分布式推进设计参数优化选择分析

为研究涡轮电力分布式推进系统(Turbo-electric Distributed Propulsion system简称TeDP)设计参数的选择,基于部件法对整个TeDP系统建立设计点性能计算模型,推导了TeDP的有效功在涡轴尾喷管和风扇系统间的最佳分配关系。在此基础上,以ECO-150-300客机作为应用对象,采用差分进化算法,以设计巡航点的耗油率作为优化目标,对TeDP的循环参数进行优化选择;然后对优化后的循环参数进行分析,并将优化结果与大涵道比涡扇发动机作对比。结果表明,优化后的巡航耗油率比原系统下降了7.68%;存在最佳风扇设计压比使风扇涵道效率最高,最佳设计压比与涵道的总压损失有关;TeDP系统的耗油率对电部件传输效率、自由涡轮效率和风扇绝热效率最为敏感,当效率分别降低1.0%时,耗油率分别上升1.0%,0.94%和0.85%;与涵道比为20的齿轮传动涡扇发动机相比,当电部件传输效率大于0.95时,TeDP才显现经济优势,当电部件传输效率接近1时,TeDP耗油率下降了5.40%。

航空发动机滑油消耗率计算与预测方法

针对航空发动机滑油箱油量测量值易受多个参数影响导致滑油消耗率难以计算和预测的问题,提出了一种改进的滑油量数据提取规则和滑油消耗率预测方法。基于密度聚类算法(Density-based spatial clustering of applications with noise,DBSCAN)等方法对发动机数据进行了清洗,获取平稳飞行状态下滑油量数据。使用最小二乘法对滑油量进行拟合,得到了滑油消耗率,平均拟合优度达到了0.86。在此基础上,利用多层感知器(Multi-layer perception,MLP)建立了滑油消耗率与飞行状态参数之间的关系,预测结果与实际值的平均绝对百分比误差为1.15%。本文提出的方法能够满足实际工程需求,为评估航空发动机滑油系统的健康状况提供了可靠参考。

机油温度对发动机油耗的影响

为了探究机油在不同温度下,粘度的改变对发动机油耗方面的影响,基于AVL 250KW电力测功机,软件控制系统为PUMA1.5.3,油耗测量采用AVL740,采用一台增压汽油发动机和一台自然吸气汽油发动机作为研究对象,在调节不同温度机油温度情况下,对发动机额定功率、进行油耗性能及排放的比较,从而探究机油温度对发动机油耗的影响。

2023年我国炼油和成品油市场回顾及2024年展望

2023年,国内成品油行业完成疫后复苏的爬坡过坎。随着宏观经济回暖、用油行业需求逐步恢复及出行活动回归正常,成品油消费迎来复苏,整体消费超疫情前水平;而供应侧,产能增长放缓,企业生产负荷在需求回升、效益好转的带动下大幅回升,攀升至历史高位;同时,替代资源强势发展,气价下行带动车用LNG经济性好转,新能源汽车自主扩张动力全面形成。2024年,成品油产业链在继续修复的基础上深化转型发展。预计国内成品油消费徘徊于低速增长通道,汽油小幅增长,航煤继续恢复,柴油略降;国内炼油产能继续增长;市场经营环境有望在政策持续系统化、全面化的基础上得到进一步优化。

某船用发电辅机性能优化

为降低某船用发电辅机常用工况油耗,采用仿真分析确定最佳配气相位、压缩比、柱塞速度;通过负荷特性试验及正交试验,确定最佳喷油器方案;通过热怠速试验选择合适的机油泵、海水泵;通过台架负荷特性试验对比发电辅机优化前、后的油耗。结果表明:该发电辅机优化后,进气关闭角对应的曲轴转角为565°,排气开启角对应的曲轴转角为135°,压缩比为15.5,最高柱塞速度提高至2.54 m/s,选用喷孔直径为0.32 mm、喷孔锥角为158°的喷油器,机油泵、海水泵体积流量分别降低10、15 m^(3)/h,辅机常用工况区油耗比原机下降4~5 g/(kW·h),达到降低油耗的目的。

低压润滑系统对柴油机可靠性和经济性的影响

为分析低压润滑系统对柴油机可靠性和经济性的影响,以某重型柴油机润滑系统为研究对象,通过仿真、测温试验和台架试验分析降低机油压力对活塞温度、主轴瓦温升、机油温升、燃油消耗率等的影响。仿真结果表明:活塞温度受机油压力和活塞喷嘴流量的影响不明显;机油温升受机油压力的影响较大,降低机油压力导致机油温升增大,机油劣化、结焦风险较高;主轴瓦、连杆大头轴瓦温升均小于设计限值。测温试验结果表明:活塞温度受机油压力影响不大,主轴瓦温升符合设计要求。台架试验结果表明:在常用工作区,机油压力由412 kPa降至240 kPa,燃油消耗率最大降幅约为0.9 g/(kW·h)。在满足柴油机可靠性的前提下应用低压润滑系统可提高经济性。

泵气损失对柴油机性能影响分析

基于某款船用中速柴油机,在当前配置状态的基础上,利用试验数据测试和GT-Power一维仿真计算手段,研究了不同配气凸轮型线、排气管直径、增压器配置对柴油机泵气损失和燃油消耗率的影响。选取部分优化方案来制作样件,并通过开发试验对比验证。结果表明,通过优化匹配可以分别将高转速高负荷工况、低转速低负荷工况的泵气损失和燃油消耗率降低到最佳水平。

单外涵变循环发动机变几何特性仿真

为了研究单外涵变循环发动机变几何性能收益,建立了一种单外涵变循环发动机总体性能仿真模型,并通过算例验证了仿真模型的计算精度。根据不同飞行状态的发动机控制规律和最优控制目标,模拟生成3种变几何方案最佳变几何参数以及最佳节流特性和高度-速度特性。结果表明:在设定的控制规律下,相对发动机常规变几何方案(方案1),尾喷管、混合器与低压涡轮导向器可调的变几何方案(方案3)使发动机地面节流状态耗油率降低1.7%~3.0%,超声速巡航推力增大14%~29%,亚声速巡航耗油率降低0.9%~3.1%,在3种变几何方案中性能收益最大;尾喷管与混合器可调的变几何方案(方案2)使发动机地面节流状态耗油率降低1.2%~2.2%,超声速巡航推力增大3%~17%,亚声速巡航耗油率降低0.9%~1.2%,在3种变几何方案中性能收益居中。发动机变几何方案的选择应综合考虑结构复杂度、可靠性、质量等方面的代价与基于特定任务需求的总体性能收益的平衡。

EGR系统脉冲转换器的理论分析与研究

随着燃油消耗法规和排放标准的日益严格,许多新技术被应用到发动机上,在发动机上应用排气再循环(EGR)技术已成为主要技术路线之一。在EGR系统的基础上,首先阐述了EGR系统和脉冲转换器的工作原理,分析了EGR系统的特点;然后结合脉冲转换器的特性,提出了利用脉冲转换器提高EGR率。根据仿真分析和试验论证脉冲转换器对提升发动机EGR率和降低发动机燃油消耗率的效果。