燃用生物柴油公交车的颗粒物排放特性

以一辆国Ⅴ柴油公交车为研究对象,通过燃用柴油和多种生物柴油比较研究其动力性、燃油经济性、颗粒物质量、数量及粒径分布特性。研究揭示:随着生物柴油的混合比例增加公交车的动力性和燃油经济性变化特性;柴油公交车的颗粒数量排放呈对数双峰分布;生物柴油公交车的颗粒物质量、23nm～2.5μm固态颗粒数量、50 nm以上的聚集态颗粒数量随着生物柴油混合比例的增加呈现的变化趋势。     

发动机燃用生物柴油的颗粒可溶有机组分及多环芳烃排放

以一台车用柴油机为样机,研究发动机燃用生物柴油的常规排放,重点探讨其颗粒(Particulate matter,PM)、可溶有机组分(Soluble organic fraction,SOF)及多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)的排放特性。所用燃油分别为柴油、生物柴油掺混配比为10%的B10燃油。结果表明,与柴油相比,该车用柴油机燃用B10燃油后颗粒、SOF和PAHs的质量排放均有所降低;NOx排放略有增加,HC和CO排放有所下降。B10燃油燃烧的颗粒SOF中醇类、酮类、醚类质量分数下降;脂类、酸类、醛类质量分数上升。在检测到的12种PAHs中,B10燃油有10种质量排放减少,尤其是苯并(a)芘等高环数致癌性的PAHs降幅明显,这表明发动机燃用生物柴油后,排气颗粒的化学成分毒性有所降低。     

单缸柴油机燃用生物柴油的排放特性分析

在EH36单缸柴油发动机试验台架上,进行了柴油机燃用纯柴油和纯生物柴油的对比性试验,分析研究了两种燃料的排放。结果表明:纯生物柴油在负荷特性中尾气中的NO浓度和速度特性中的烟度值大大低于相同工况下的纯柴油。     

柴油/生物柴油混合燃料喷雾特性试验研究

为了揭示柴油/生物柴油混合燃料的喷雾特性,本试验重点研究了生物柴油在不同掺混比下的喷射与雾化性能。试验利用马尔文激光粒径检测仪分别测试了在燃油喷束200mm、300mm、400mm和500mm处的燃油喷雾索特直径(SMD)和粒径累积体积分布情况,同时还利用喷纸试验法对B0、B10、B20、B50和B100燃油喷束的喷雾锥角进行了测试。试验结果表明,随着生物柴油掺混比的增大,混合燃料的喷雾锥角逐渐减小,但燃油喷雾索特直径呈逐步增大的趋势。另外试验还发现,喷射燃油粒径累积体积分布随掺混比的增大向较大粒径方向移动,这表明燃油喷雾中大粒径液滴数量增多,燃油喷雾质量变差。     

单缸柴油机上的纯生物柴油性能分析

为降低柴油机的废气排放,在EH36单缸柴油发动机试验台架上,进行了柴油机燃用纯柴油和纯生物柴油的对比性试验,分析研究了柴油机的燃烧特性、动力性、经济性。结果表明:纯生物柴油在低转速大扭矩工况下的经济性能较好;加速过程中,燃料消耗量大且柴油机的功率有所下降;最大扭矩和最大转速均比纯柴油略低,纯生物柴油的爬坡性能略差。     

调合生物柴油燃烧及颗粒物组分的试验研究

为深入研究不同比例调合生物柴油对发动机燃烧特性及颗粒物组分的影响,在一台单缸四冲程发动机上进行了调合生物柴油燃烧及颗粒物排放的试验研究。利用燃烧分析仪研究调合生物柴油对发动机燃烧过程的影响,利用热重分析仪(TGA)、气相色谱/质谱联用仪(GC-MS)研究调合生物柴油对颗粒物热重特性、挥发性有机物(VOCs)质量分数及有机可溶成分(SOF)和多环芳香烃(PAHs)组分的影响规律。研究表明:随着生物柴油掺混比的增加,发动机最高爆发压力及压力升高率峰值增加,压力曲线前移,预混放热率峰值随生物柴油掺混比增加而减小。与B0相比,燃用B20调合生物柴油,最高爆发压力增加了5.59%,对应的曲轴转角提前了3°CA。燃用调合生物柴油后VOCs及SOF组分略有增加,燃用B0、B5、B10及B20后颗粒物中VOCs组分的质量分数分别为12.28%、15.09%、23.06%和26.94%,SOF组分的质量分数分别为29.32%、32.08%、34.26%和35.67%,燃用B20后排放颗粒物中总PAHs降低了10.26%。     

微运动下高压油泵柱塞副瞬态泄漏研究

共轨高压油泵的泵油能力及容积效率受柱塞副燃油泄漏的制约,而柱塞的微运动特性对柱塞副的泄漏有着重要影响。基于结构动力学与流体动力润滑理论,建立柱塞副微运动过程的动力学模型,分析柱塞偏移、倾斜的微运动特性;综合考虑柱塞微运动、柱塞副的结构变形以及燃油物性变化的影响,建立升程段柱塞副燃油瞬态泄漏数学模型,获得了微运动下柱塞副工作过程的瞬态泄漏特性,并进行试验验证。计算结果表明:在柱塞升程段,柱塞的偏移量先增大后减小,柱塞倾斜角先减小后而增大;相比柱塞副实测的瞬态泄漏,考虑微运动下的瞬态泄漏平均误差为3%,而不考虑微运动的瞬态泄漏平均误差为20%,所以考虑微运动的瞬态泄漏模型更精确。     

预喷射技术对生物柴油发动机热性能的优化

利用GT-suite软件对某柴油机燃用生物柴油在特定工况下采用预喷射方案缸内工作过程进行了数值计算，测定了不同掺合比生物柴油理化特性，分析了不同掺合比、预喷量和预喷-主喷间隔对燃烧过程的影响。研究结果表明，柴油机扭矩随着生物柴油掺合比增大而下降；在主喷角不变时，不同掺合比生物柴油对应主喷阶段放热率变化较小；相同预喷-主喷间隔和掺合比生物柴油时，随着预喷量增加，预喷阶段放热率峰值增大，主喷射阶段放热率峰值降低且前移；相同主喷角和掺合比生物柴油时，不同预喷-主喷间隔生物柴油放热率曲线形状趋于一致，预喷阶段放热率随着间隔角增大而前移。预喷射能有效地降低发动机排放，综合扭矩、放热率与排放值确定B5-5%-20方案为改善该柴油机在2200r·min^-1工况下最优预喷射方案。     

生物柴油混合燃料的排放特性研究

本试验通过对燃烧生物柴油对发动机排放污染物的测量和分析,探讨了生物柴油降低柴油机排气污染物的机理。研究结果表明:在同一稳定工况下,随着生物柴油加柴油中入比例的上升,燃烧排放物中的CO和HC比柴油排放呈现线性下降,NOx排放有所上升,而CO2排放一本在同一水平。     

机外预热柴油对发动机性能影响的试验分析

柴油温度的变化会对其黏度、密度等理化性质产生影响,进而使柴油发动机的性能和工况表现出明显差异.本文首先通过组建基于柴油预热的发动机性能试验系统,选择3个牌号、6个温度点的柴油,开展全负荷速度特性试验及负荷特性试验.试验结果表明,柴油温度升高会导致发动机功率、燃油消耗率降低,并且后者降幅更加明显;光吸收系数升高,说明随着柴油温度上升,排放污染物浓度也相应升高.     

Alternative and low sulfur fuel options: boundary lubrication performance and potential problems

Studies of alternative fuels at Penn State include biodiesel, dimethyl ether (DME) and low sulfur diesel fuels. The fuel studies include bench tests, laboratory engine tests and vehicle tests. DME was evaluated in a campus shuttle bus operating on its regular campus route. A 25:75 vol% mixture of DME and diesel fuel was used. Laboratory engine tests of oxygenated fuels, including biodiesel, resulted in significant particulate reductions. However, some alternative fuels exhibit low lubricity. Bench tests comparing friction and wear characteristics of the fuels are described.     

Effect of antioxidants on the oxidative stability and combustion characteristics of biodiesel fuels in an indirect-injection (IDI) diesel engine

Biodiesel fuels that consist of saturated and unsaturated long-chain fatty acid alkyl esters are an alternative diesel fuel produced from vegetable oils or animal fats. However, autoxidation of biodiesel fuels during storage is easily caused by air, reducing fuel quality by adversely affecting its properties such as kinematic viscosity and acid value. One approach to improve the resistance of biodiesel fuels to autoxidation is to mix them with antioxidants. This study investigated the effectiveness of five such antioxidants in mixtures with biodiesel fuels produced by three biodiesel manufacturers: butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), tert-butylhydroquinone (TBHQ), propyl gallate (PrG) and α-tocopherol. An engine test was also performed to investigate the combustion characteristics of biodiesel fuel with antioxidants in an indirect-injection (IDI) diesel engine. Oxidation stability was determined using Rancimat equipment. The results showed that TBHQ, BHA, and BHT were the most effective and α-tocopherol was the least effective in increasing the oxidation stability of biodiesel. The combustion characteristics and exhaust emissions in diesel engine were not influenced by the addition of antioxidants in biodiesel fuel. This study recommends TBHQ and PrG to be used for safeguarding biodiesel fuel from the effects of autoxidation during storage.     

Experimental investigation of nanoparticle formation characteristics from advanced gasoline and diesel fueled light duty vehicles under different certification driving modes

This paper mainly focused on the comparison of nanoparticle size distribution and number concentration level characteristics with gasoline and diesel fueled light duty vehicles. In the engine research, particle size distribution and number concentrations were analyzed by a DMS500 with engine parameters. Time-resolved particle number concentration levels from test vehicles were measured by a golden particle measurement system (GPMS) as recommended by a Particle Measurement Programme (PMP) on certification modes such as New European Driving Cycle (NEDC), Federal Test Procedure (FTP)-75, and Highway Fuel Economy Test (HWFET). In addition, particle emission characteristics from vehicles were analyzed by DMS500 during transient and high-speed driving conditions. From the results, we found that the formation of particles was highly dependent on vehicle speed and load conditions for each mode. The diesel vehicle equipped with a particulate filter showed substantial reduction of the total particle number whose number concentration was equivalent to that of the gasoline vehicle. The nucleation mode particles from gasoline fuel were mainly emitted; however, the accumulation mode particles from the diesel fuel were generally analyzed. This paper was recommended for publication in revised form by Associate Editor Kyoung Doug Min Simsoo Park received his B.S. and M.S. degrees from Seoul National University in 1977 and 1979, respectively, and a Ph.D. from the State University of New York at Stony Brook. He served as a Chief Research Engineer at Hyundai Motor Company, a Director for Publication of the KSME, a Technical Advisor of Hyundai-Kia Motor Company, and an Editing Director, Project Director, International Director, Accounting Director, and General Affair Director of KSAE. He is currently Vice President and Editor-in-Chief of IJAT at KSAE and a professor in school of mechanical engineering at Korea University. Hyungmin Lee received his B.S. degrees from Republic of Korea Naval Academy in 1997 and his M.S. degrees from Korea University in 2005, respectively. He served as an Operation Officer, Command Engineer Officer at various naval vessels. He is currently Ph.D. course in school of mechanical engineering at Korea University and his rank is a Lieutenant Commander of Korea Navy.     

An experimental study on the performance and emission characteristics of a CI engine fuelled with Jatropha biodiesel and its blends with diesel

The performance and emission characteristics of a compression ignition engine using mixture of jatropha biodiesel and mineral diesel have been experimentally investigated. It is observed that brake specific fuel consumption increases with higher percentage of biodiesel in the blends. Brake thermal efficiency decreases with the increased percentage of biodiesel in the blends. The maximum efficiency is found to be 29.6% with pure diesel and 21.2% with pure biodiesel. Carbon mono-oxide and hydrocarbon emissions are improved with the addition of biodiesel to diesel. NO_x emission is found to be increased with pure biodiesel by 24% compared to mineral diesel.     

Characterization of engine oil additive packages on diesel particulate emissions

This study investigated the impact of engine oil formulation on particulate matter (PM) characteristics from a light-duty diesel engine. The test engine was a 1.6 L Euro-5 diesel engine operated from low- to high-speed and high-load conditions. Specially formulated nonadditive containing base oil and genuine oil were evaluated. For diesel PM characterization, physicochemical analytic procedures were conducted on engine oil formulation, oil flushing, PMs sampling, morphology, and particle constituent determination. Size-resolved particle number (PN) concentration at the engine-out position was evaluated by differential mobility spectrometer (DMS). Nucleation mode particles originating from engine oil consumption during the expansion stroke had a higher concentration from genuine oil than those from base oil. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the morphology patterns and atomic compositions with engine oil packages. From the SEM analysis, spherical PM of nucleation and accumulation mode particles were agglomerated on a quartz filter. In the XPS spectrum, more engine oil additive fractions of Ca, P, and Zn were found in the PM sample from genuine oil. In conclusion, the variation of physicochemical engine oil properties and additive amounts had strong contributions to engine oil derived PN emissions, morphology, and additive metal compositions in the exhaust gas stream.

     

Effect of Reciprocation Frequency on Friction and Wear of Vibrating Contacts Lubricated with Soybean-Based B100 Biodiesel

The use of renewable, bio-based fuels has become increasingly widespread in recent years, with a major example being biodiesel, a bio-derived alternative to Number 2 diesel fuel. The increased usage of biodiesel gives rise to an augmented need to understand its tribological effects on critical engine components. This study focused on determining the tribological performance of soybean-based B100 (i.e., pure) biodiesel within a fuel injector with varying oscillating frequency by performing a series of linear reciprocating tribological tests of biodiesel-lubricated interfaces with varying reciprocating frequency. Comparison of friction coefficient variation with reciprocating frequency indicated a transition from boundary lubrication to hydrodynamic lubrication as the frequency increased, while hysteresis loop and energy loss observations showed a transition between full stick and partial slip contact with increasing frequency. However, observations of induced wear showed the wear to increase with increasing frequency, most likely due to the augmented number of sliding cycles as well as an increased degree of interfacial slip.     

Emission characteristics of exhaust gases and nanoparticles from a diesel engine with biodiesel-diesel blended fuel (BD20)

This experimental study sought to investigate the characteristics of the exhaust emissions, and nanoparticle size distribution of particulate matter (PM) emitted from diesel engines fueled with 20% biodiesel-diesel blended fuel (BD20). The study also investigated the conversion efficiency of the warm-up catalytic converter (WCC). The emission characteristics of HC, CO, NOx and nano-sized PM were also observed according to engine operating conditions with and without exhaust gas recirculation (EGR). The study revealed that the maximum torque achievable with the biodieseldiesel blended fuel was slightly lower than that achievable with neat diesel fuel at high-load conditions. Smoke was decreased by more than 20% in all 13 modes. While the CO and THC emissions of BD20 slightly decreased, the NOx emission of BD20 increased by 3.7%. Measured using the scanning mobility particle sizer (SMPS), the total number and total mass of the nanoparticles in the size range between 10.6nm and 385nm were reduced by about 10% and 25%, respectively, when going from D100 to BD20. The particle number and mass for both fuels were reduced by about 43% when going from with EGR to without EGR. When EGR was applied in the engine system, the particle number and mass were reduced by 24%, and 16%, respectively, when going from D100 to BD20.     

Effects of B100 Biodiesel on Injector and Pump Piston

In this study, the effects of biodiesel use in a diesel engine on an injector and fuel injection pump piston were experimentally analyzed. To this end, two engines with the same technical specifications were used; petroleum diesel was used in one of the engines and 100% (B100) biodiesel was used in the other engine. After the engines were run for 200 h, their injectors and pump pistons were examined and compared by performing scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis measurements. SEM and EDX analyses showed significant structural changes on the surfaces of the injector nozzle and pump piston in the event that B100 is used.     

Performance and emission characteristics of conventional engine running on jatropha oil

A number of studies have recently been conducted to determine a suitable alternative fuel for conventional engine. The use of renewable fuels such as bio-ethanol, biogas, and biodiesel is thus investigated for this purpose. Performance tests were conducted on an indirect injection compression ignition engine by using diesel, unheated jatropha oil (JO), and preheated JO as fuels. The effects of fuel injection pressure and fuel inlet temperature on engine performance and emission for the different fuels were analyzed. Test results showed that the brake thermal efficiency of the engine with heated JO oil is superior to that with unheated JO, increasing from 28.4% with neat unheated JO to a maximum of 30.8%. The brake specific fuel consumption was reduced from 0.301 kg/kWh to 0.266 kg/kWh. Smoke opacity was also reduced relative to the neat unheated JO operation.