燃用F-T柴油/甲醇微乳化燃料对柴油机排放特性影响

在某增压柴油机上分别燃用0~#柴油、F-T柴油和三种不同配比的F-T柴油/甲醇微乳化燃料(简称FT微乳化燃料),分析了其燃烧排放特性,试验中柴油机结构和参数未进行调整。研究结果表明:相比于0~#柴油,燃用FT微乳化燃料缸内压力下降,放热率峰值降低。FT微乳化燃料有效降低了CO、NO_x和碳烟等常规排放,平均降幅范围分别为20%~40%、25%~27%和65%~97%。非常规排放中未燃甲醇排放随着燃料中甲醇比例的增加而增加,随着负荷增大而降低;甲醛排放均较0~#柴油有所增加,随负荷变化趋势与未燃甲醇相同,但并未与燃料中甲醇含量形成线性相关。     

多次喷射策略对正戊醇-柴油混合燃料燃烧及有害排放影响的模拟研究

为了揭示含氧燃料与喷油策略耦合对发动机燃烧、性能和排放特性影响的机制,基于三维仿真软件CONVERGE,耦合化学反应动力学机理,研究了正戊醇—柴油混合燃料在不同喷射策略下燃烧与有害排放物的生成过程。结果表明,正戊醇促进了燃烧过程,燃用正戊醇—柴油混合燃料时,缸内最高燃烧压力和燃烧放热峰值增大,发动机平均指示压力（indicated mean effective pressure,IMEP）升高,CO、总碳氢化合物（total hydrocarbons,THC）和碳烟排放降低,但NOx排放升高。采用大比例预喷射策略可以促进主喷燃烧过程,提高缸内温度,增大IMEP,但导致CO及THC排放升高,而小预喷间隔会导致碳烟排放增加。后喷射策略导致发动机IMEP降低,但可以降低NOx排放。在小后喷间隔下碳烟排放显著降低,但在大后喷间隔下碳烟排放明显升高。研究表明,正戊醇柴油混合燃料采用大预喷间隔及小后喷间隔的3次喷油策略,能够获得最高的IMEP及最低的有害物排放。     

柴油机燃用新型戊醇混合燃料的燃烧和排放特性

戊醇是一种能量密度较高的新一代生物质燃料,与低碳醇相比,具有与柴油更好的互溶性和较高的十六烷值.在一台单缸柴油机上研究对比了不同喷油时刻下3种不同掺混比例的戊醇、生物柴油和柴油混合燃料的燃烧和排放特性.结果表明:与柴油相比,添加戊醇后,混合燃料的最高放热率升高,燃烧持续期缩短,热效率提高.戊醇混合燃料的碳烟排放显著降低,其中戊醇-生物柴油-柴油混合燃料的碳烟排放降低效果最佳,最高降幅为85.7%;且NOx排放下降,最大减少了11.2%,即采用戊醇混合燃料可实现碳烟和NOx排放的同时降低.     

柴油机燃用生物柴油-乙醇-水微乳化燃料性能研究

为研究生物柴油-乙醇-水微乳化燃料在柴油机上的应用,在单缸直喷式柴油机上,对生物柴油和生物柴油-乙醇-水微乳化燃料的燃烧特性、经济性和排放进行试验研究。研究结果表明:与生物柴油相比,生物柴油-乙醇-水微乳化燃料的压力、压力升高率及放热率曲线明显后移;峰值燃烧压力和峰值瞬时燃烧放热率增加,燃烧更加完全、放热更加集中;瞬时燃烧放热率第二峰值明显降低,瞬时燃烧放热率曲线型心转角在中高负荷更加靠近上止点,循环等容度和有效效率明显提高;燃料消耗率增加而比能耗略有降低;NOx和烟度排放明显降低。研究结果表明:生物柴油-乙醇-水微乳化燃料是节能、环保的柴油机代用燃料。     

甲醇-柴油混合燃料对发动机燃烧及排放特性的影响

在一台YTR3105直喷式柴油机上进行了小比例甲醇-柴油混合燃料发动机的燃烧及排放特性试验研究。结果表明:在相同的平均有效压力和转速下,随着甲醇含量的增加,燃料着火延迟相应增大,使得燃烧过程向上止点后移动。混合燃料的滞燃期比柴油长,预混燃烧放热率峰值增大,燃烧持续期缩短,缸内最大爆发压力和压力升高率增加。与纯柴油相比,甲醇-柴油混合燃料HC排放有所升高,但NOx和碳烟排放降低。大负荷时,CO排放显著下降。     

柴油机燃用混合替代燃料的燃烧与排放特性

将生物柴油和F-T柴油(F-T diesel)进行掺混,并将其混合燃料应用于4100QBZL柴油机上.在未对原机做任何改动的情况下,研究了该机燃用不同体积配比混合燃料时的燃烧特性及NOx和碳烟排放性能.研究表明,与0#柴油相比,该机的预混燃烧放热峰值降低、扩散燃烧放热峰值升高、燃烧更柔和;NOx排放随着生物柴油掺混比例的增大而升高;碳烟排放显著下降,较0#柴油的降低幅度高达37%;低比例的混合燃料对NOx排放和碳烟排放的trade-off关系有明显改善.生物柴油与F-T柴油混合燃料宜在较低的生物柴油掺混比例范围内使用.     

重型车用柴油机燃用乳化柴油的燃烧与排放特性试验研究

在不改变发动机任何参数的情况下,对高压共轨重型车用柴油机分别燃用柴油和乳化柴油的燃烧与排放特性进行了对比试验研究。试验结果表明:与纯柴油相比,乳化柴油在试验工况下着火滞燃期延长,瞬时放热率峰值提高,燃烧持续期变短;缸内最高压力在低负荷时较柴油高,但在高负荷时较柴油低;在全负荷下,相比于柴油,燃用乳化柴油有效功率平均降低了16.90%,但发动机有效热效率平均提高了2.42%;燃用乳化柴油在常用转速1 800 r/min的负荷范围内时,NOx和碳烟排放分别比柴油平均降低了12.77%和58.90%,改善了NOx和碳烟排放的权衡曲线关系;高负荷时,燃用乳化柴油的CO排放减少,但HC排放增加。     

柴油/丙烷混合燃料发动机燃烧和排放特性研究

比较了柴油和丙烷的主要理化性能;在一台单缸直喷式柴油机上开展了燃用柴油和柴油/丙烷混合燃料时的发动机燃烧和排放特性研究.研究结果表明：在相同工况下,与燃用柴油相比,燃用柴油/丙烷混合燃料时的有效热效率增加,柴油/丙烷混合燃料的有效热效率随丙烷比例的增加而稍有增加,混合燃料的滞燃期和燃烧持续期随丙烷比例的增加而缩短;缸内最大压力,最大燃烧放热率,最高平均燃烧温度随丙烷比例的增加而增加.燃用丙烷柴油混合燃料可同时降低CO、HC和碳烟排放,但NOx排放有所增加.     

柴油机燃用煤基含氧混合燃料的燃烧及排放特性

在F-T柴油中添加不同比例的丁醇、生物柴油燃料,并与0#柴油做了燃烧及排放特性的对比研究。研究结果表明:混合燃料的预混合燃烧期、扩散燃烧期、缸压峰值与放热率峰值均介于0#柴油与F-T柴油之间;相对于0#柴油,混合燃料燃烧始点提前,CA50增加,燃烧放热中心向后推迟,燃烧放热率第一峰值降低;所在相位提前,预混合燃烧放热量降低,有利于降低燃烧过程的最高温度,实现低温燃烧,第二峰值升高,扩散燃烧所占比重增加;在转速为2 000 r/min时,混合燃料(N10,N20和N10B10)的NOx排放量较0#柴油分别降低了23.40%,26.95%和23.25%,其中主要是NO的降低,NO2的排放量因为低温燃烧反而略有上升;外特性下,碳烟排放量较0#柴油分别平均降低71.47%,77.16%,68.80%。     

甲醇/生物柴油/F-T柴油混合燃料燃烧特性与排放特性研究

选取煤基燃料F-T柴油和甲醇,并辅以生物柴油,配制成甲醇/生物柴油/F-T柴油混合燃料,在未做调整的四缸增压中冷柴油机上进行试验研究。结果表明:混合燃料的燃烧放热率峰值、压力升高率峰值和缸内压力峰值均随混合燃料中生物柴油比例的增加而增加,且对应的相位延迟;外特性下燃用混合燃料时,碳烟、氮氧化物的排放量明显降低,在低转速下一氧化碳降低幅度较大,混合燃料对甲醛也有较大幅度的减排作用。     

不同海拔下VGT对含氧燃料柴油机性能的影响

利用大气压力模拟装置,试验研究了可变几何截面涡轮增压器(VGT)对高压共轨柴油机分别燃用纯柴油和生物柴油-乙醇-柴油(BED)含氧燃料的经济性、排放特性及燃烧特性的影响。结果表明:随着海拔的升高,柴油机经济性恶化,氮氧化物(NO_x)排放降低,而一氧化碳(CO)和碳氢化合物(HC)排放及烟度升高。燃用纯柴油与含氧燃料,随着VGT喷嘴环开度的增大,柴油机的经济性均有不同程度的恶化,而CO、HC排放及排气烟度也都有不同程度的升高。在高海拔地区,燃用纯柴油的经济性优于含氧燃料,但使用含氧燃料有助于改善柴油机的CO、HC排放及烟度。在中等负荷工况下,NO_x排放随着VGT喷嘴环开度的增大呈现先减小后增大的趋势;在高负荷工况下,放热率峰值和最高气缸压力均随着VGT喷嘴环开度的增大而降低,从而降低了NO_x排放。     

相同氧含量醇类混合燃料燃烧和排放特性差异研究

对一台4缸发动机燃用相同氧浓度的不同醇类混合燃料进行了试验研究,以对比不同三元燃料柴油机在相同转速不同负荷情况下的燃烧特性和常规排放的差异。试验结果表明:甲醇混合燃料在醇类混合燃料中获得最高的燃烧压力,而丁醇混合燃料的热释放率最高。与普通柴油相比,戊醇混合燃料在不同混合物中具有相对最佳的CO和未燃碳氢排放,甲醇混合燃料可获得最优的氮氧化物排放;乙醇混合燃料减小颗粒物效果明显,最大可以减少22.4%～55.6%的颗粒物数量浓度和3.4%～12.8%的颗粒物粒径,其中乙醇混合燃料的核态颗粒物和聚集态颗粒物排放量也最低,戊醇混合燃料达到最高(除高负荷外)。     

柴油机燃用低比例小球藻生物柴油-柴油混合燃料的试验研究

以野生小球藻生物柴油(Chlorella Biodiesel Fuel,CBF)-柴油作为混合燃料,利用186FA柴油机进行台架试验。在CBF的掺混比例分别为0%,3%,5%(B0,B3,B5)时,对柴油机的动力性、燃料燃用的经济性和燃烧及排放特性进行了比较分析。试验分析表明:柴油机燃用混合燃料时,与燃用纯柴油相比,随着CBF掺混比例的增加,其扭矩和功率略有下降,最大降幅均为4%;柴油机的油耗率和能耗率略有上升,且在高、中负荷时更为明显;柴油机的缸内压力、放热率峰值稍有减小,而压力升高率峰值稍有增大,缸内压力峰值最大降幅为3.4%,放热率峰值最大降幅为12.8%,压力升高率峰值最大增幅为13.7%;柴油机滞燃期缩短了0.5~1.0°CA、燃烧持续期延长了1.0~2.0°CA,缸内压力、压力升高率和放热率峰值的出现时刻均提前了1.0~2.0°CA,燃烧速度加快;HC,CO和碳烟的排放均有所降低,而NOX的排放逐渐增多,全负荷时HC和碳烟排放的最大降幅分别为14.1%和31.7%,NOX排放的最大增幅为9.7%,CO排放的降幅为6%~12%。     

柴油喷射压力对柴油/甲醇二元燃料发动机燃烧和排放影响的试验研究

在一台增压中冷电控共轨柴油机上,研究了柴油喷射压力对柴油/甲醇二元燃料(DMDF)燃烧和排放特性的影响。研究表明:柴油喷射压力较低时,DMDF模式压缩冲程的缸压要低于纯柴油模式,降幅随着甲醇替代率的增大而增大;而柴油喷射压力较高时,降幅较小,甲醇替代率为20%时的最大缸压要略高于纯柴油模式,且对应的最大放热率明显高于纯柴油模式和甲醇替代率为40%时。DMDF模式的NO_x排放量随着甲醇替代率的增加而降低,相同替代率时随着柴油喷射压力的增加而增加。CO和总碳氢(THC)排放量随柴油喷射压力的增加略有降低,随替代率的增加几乎线性增加。在低柴油喷射压力下,DMDF模式可以明显降低烟度,且排放量随着替代率的增加而减小,最多可减少约35%的碳烟排放。其他柴油喷射压力时,烟度随着甲醇替代率的增加而基本保持不变。     

Preparation,characterization, engine combustion and emission characteristics of rapeseed oil based hybrid fuels

In this study, hybrid fuels consisting of rapeseed oil/diesel blend, 1% aqueous ethanol and a surfactant (oleic acid/1-butanol mixture) were prepared and tested as a fuel in a direct injection (DI) diesel engine. The main fuel properties such as the density, viscosity and lower heating value (LHV) of these fuels were measured, and the engine performance, combustion and exhaust emissions were investigated and compared with that of diesel fuel. The experimental results showed that the viscosity and density of the hybrid fuels were decreased and close to that of diesel fuel with the increase of ethanol volume fraction up to 30%. The start of combustion was later than that of diesel fuel and the peak cylinder pressure, peak pressure rise rate and peak heat release rate were higher than those of diesel fuel. The brake specific fuel consumption (BSFC) of hybrid fuels was increased with the volume fraction of ethanol and higher than that of diesel. The brake specific energy consumption (BSEC) was almost identical for all test fuels. The smoke emissions were lower than those for diesel fuel at high engine loads, the NO_x emissions were almost similar to those of diesel fuel, but CO and HC emissions were higher, especially at low engine loads.     

Influence of pentanol and dimethyl ether blending with diesel on the combustion performance and emission characteristics in a compression ignition engine under low temperature combustion mode

Dimethyl ether (DME) and n-pentanol can be derived from non-food based biomass feedstock without unsettling food supplies and thus attract increasing attention as promising alternative fuels, yet some of their unique fuel properties different from diesel may significantly affect engine operation and thus limit their direct usage in diesel engines. In this study, the influence of n-pentanol, DME and diesel blends on the combustion performance and emission characteristics of a diesel engine under low-temperature combustion (LTC) mode was evaluated at various engine loads (0.2–0.8 MPa BMEP) and two Exhaust Gas Recirculation (EGR) levels (15% and 30%). Three test blends were prepared by adding different proportions of DME and n-pentanol in baseline diesel and termed as D85DM15, D65P35, and D60DM20P20 respectively. The results showed that particulate matter (PM) mass and size-resolved PM number concentration were lower for D85DM15 and D65P35 and the least for D60DM20P20 compared with neat diesel. D60DM20P20 turned out to generate the lowest NO_x emissions among the test blends at high engine load, and it further reduced by approximately 56% and 32% at low and medium loads respectively. It was found that the combination of medium EGR (15%) level and D60DM20P20 blend could generate the lowest NO_x and PM emissions among the tested oxygenated blends with a slight decrease in engine performance. THC and CO emissions were higher for oxygenated blends than baseline diesel and the addition of EGR further exacerbated these gaseous emissions. This study demonstrated a great potential of n-pentanol, DME and diesel (D60DM20P20) blend in compression ignition engines with optimum combustion and emission characteristics under low temperature combustion mode, yet long term durability and commercial viability have not been considered.     

生物含氧燃料成分对柴油机性能影响的试验研究

将占体积比80％的柴油分别掺混20％乙醇、20％生物柴油以及10％乙醇和10％生物柴油的混合物,连同纯柴油组成E20、B20、E10810和柴油共4种燃料,在一台4缸柴油机上进行燃烧、性能及排放特性试验研究。结果表明：含氧燃料成分的不同对折合油耗率基本不产生影响,但对燃烧和排放特性影响较大。发动机燃用E20的缸内最大爆发压力较柴油要大,B20、E10810较柴油要小;含氧燃料中生物柴油的加入使最大压力升高率减小,燃烧变得柔和;含氧燃料的放热时刻均落后于柴油的放热时刻。含氧燃料成分在中低负荷下对HC和CO的排放影响较大,随着含氧燃料中乙醇比例的增加HC和CO排放增加,在中高负荷下,3种含氧燃料的HC和CO排放基本相当;除了在2300r／min的中低负荷下含氧燃料的HC和CO排放较柴油高以外,其它工况下含氧燃料的HC和CO排放较柴油要低。含氧燃料成分不同对NOx排放的影响很小,3种含氧燃料的NOx排放都比柴油低。3种含氧燃料的碳烟排放较柴油要低,而且随含氧燃料中乙醇比例的增加,碳烟排放减小。     

柴油-甲醇微乳化燃料的制备及燃烧特性研究

本文根据乳化和微乳化理论选择油酸作为表面活性剂配制了多种配比的柴油 甲醇微乳化燃料。微乳化燃料获得了与柴油相近的发动机动力性和热效率,NOX排放比燃用柴油时高,碳烟排放比燃用柴油时低。随供油提前角的推迟,NOX排放快速下降,碳烟排放变化不大,推迟供油可使甲醇混合油获得更好的排放水平。由于甲醇汽化潜热大、乳化燃料具有微爆效应,故在小负荷时混合燃料滞燃期比柴油时大,而在大负荷时两者较接近。随混合油含醇率的增加,预混燃烧峰值也随之增加。     

Performance of a common rail diesel engine using biodiesel of waste cooking oil and gasoline blend

High viscosity, high pour point and low volatility are the major application blocks for biodiesel. In this study gasoline is mixed with biodiesel and they can be soluble with each other at any proportion. Combustion and emission characteristics are investigated on a turbocharged, in-line 6-cylinder, common rail diesel engine. Results showed that pour points, viscosities and distillation temperatures obviously decrease with gasoline ratio. Peak combustion pressures of biodiesel/gasoline blend fuels increase slightly. Ignition delays, peak heat release rates and combustion temperatures increase at partial and medium loads. HC and CO emissions increase at partial and medium loads and drop at high loads. NO_X emissions of blend fuels grow by 4.2% and 6.7% compared with biodiesel averagely at 1400r/min, while soot emissions decline by 31.6% and 38.6%. For ultrafine particles (<220 nm), diameters to peak number concentration of blend fuels are smaller than that of biodiesel. Number concentrations decrease by 30% and 49% averagely compared to biodiesel. Especially, gasoline plays a significant reduction role on ultrafine particles at low and medium loads and soot emissions at high loads.     

Study on combustion characteristics and particulate emissions of a common-rail diesel engine fueled with n-butanol and waste cooking oil blends

Biodiesel is a promising alternative fuel because of its renewability and extensive source of raw materials. Butanol can be blended in biodiesel to reduce the kinematic viscosity and promote the fuel atomization. In this respect, biodiesel was blended with 10% and 20% n-butanol, and the combustion characteristics and particulate emissions of the fuel blends were tested in a turbocharged, 6-cylinder, common rail diesel engine at a constant speed of 1400 rpm under seven engine loads. The experimental results show that under various engine loads, all of the butanol and biodiesel fuel blends provide faster combustion than diesel due to the higher oxygen content of n-butanol and the lower cetane number of butanol which results in stronger premixed combustion. The addition of butanol is beneficial to concentrating the heat release and thus shorten the combustion duration. With an increased proportion of butanol, soot emissions of butanol and biodiesel fuel blends decrease, the number concentration and volume concentration of ultrafine particles (UFPs) reduce noticeably. Meanwhile, the geometric mean diameters of UFPs decrease with an increase in butanol. With an increase of the engine loads, the number concentration peaks of UFPs gradually transfer from the size range of nucleation mode particles (NMPs) to the size range of accumulation mode particles (AMPs) due to the elevated combustion temperatures and high equivalence ratios. Moreover, biodiesel and fuel blends exhibit a higher percentage of NMPs as compared to diesel because of the fuel-bound oxygen, zero aromatics, and low sulfides.