EGR对生物柴油/异丁醇混合燃料燃烧与排放的影响

在一台四缸四冲程水冷高压共轨柴油机上研究了生物柴油/异丁醇混合燃料在不同EGR率下的燃烧及排放特性.试验结果表明:随EGR率的升高,缸内压力和放热率峰值降低,燃料滞燃期延长,燃烧持续期先缩短后延长,NO排放与核模态颗粒物数密度降低;当EGR率小于6%时,CO和HC污染物的排放都保持在较低水平.相较于生物柴油,燃用混合燃料降低CO污染物的排放;随异丁醇掺混比例的增加,缸内压力与放热率峰值逐渐升高,CO排放降低,但HC与NO的排放逐渐升高,核模态颗粒物数密度升高,积聚态颗粒物数密度和颗粒物质量浓度有不同程度的下降.     

GTL燃料发动机排气颗粒数密度和粒径分布的试验研究

采用两级稀释取样装置和扫描迁移颗粒粒径分析仪(SMPS),研究了燃用天然气合成油(GTL)发动机排气颗粒的数密度和粒径分布特征,并同原柴油机的颗粒排放进行了比较,发现发动机燃用GTL时,中间转速(n=1400 r/min)下,排气颗粒多呈峰值粒径为50～80nm的单峰对数正态分布;高转速(n=2200r/min)下,呈分别包含核模态(峰值粒径为20～30nm)和积聚模态(峰值粒径为50～80nm)的双峰对数正态分布。而燃用柴油时,所有测试工况下,排气颗粒均呈包含核模态和积聚模态的双峰对数正态分布。与燃用柴油相比,怠速工况下,燃用GTL后总颗粒数密度和体积分数没有显著下降,而其它工况下总颗粒数密度和体积分数显著下降,其中总数密度均下降一个数量级,总体积分数下降20%～60%;燃用CTL后,排气中核模态数密度显著下降,某些工况下积聚模态数密度有所下降,这与GTL燃料中的芳香烃和硫含量均较低有关。     

高原环境下聚甲氧基二甲醚对柴油机燃烧和排放性能的影响

以掺混不同体积分数（10%、20%）聚甲氧基二甲醚（polymethoxydimethyl ethers, PODE）的柴油为含氧燃料,采用某军用泵机组柴油机进行发动机台架试验,通过控制进气压力模拟高原地区柴油机进气条件,模拟海拔0~4 000 m时含氧燃料对发动机外特性、燃烧特性和排放性能的影响。结果表明,低海拔下,该柴油机燃用掺混PODE燃料后功率低于燃用0号车用柴油,燃油消耗率升高。随海拔升高,柴油机燃用掺混PODE燃料后功率和燃油消耗率逐渐接近燃用纯柴油。当海拔达到4 000 m时,柴油机燃用掺混20%体积分数的PODE燃料后功率平均增加3.6%,燃油消耗率平均下降1.2%。海拔4 000 m、柴油机2 000 r/min、100%负荷下,燃用掺混PODE燃料后燃烧位移前移,缸压峰值、放热率峰值提高,滞燃期和燃烧持续期缩短。不同海拔下,燃用掺混PODE燃料后CO、HC排放显著降低,NO_x排放有所增加。     

共轨柴油机燃用不同配比生物柴油的性能与排放特性

对某共轨柴油机燃用石化柴油、生物柴油及其混合燃料的动力性、经济性和排放特性进行了研究.在未对原机做任何改动的情况下,分别燃用了0%、5%、10%、20%和100%的5种不同体积配比的餐饮废油制生物柴油与石化柴油的混合燃料,分析比较了不同生物柴油配比对发动机功率、燃油消耗率,以及CO、HC、NO_x和烟度排放的影响.研究表明:共轨柴油机燃用生物柴油与石化柴油混合燃料后,功率略有下降,燃油消耗率有所上升;烟度、CO和HC排放减少,且随着生物柴油掺混比例的升高而降低;NO_x排放上升,且随着生物柴油掺混比例的升高而增加.     

连续再生颗粒捕集器对燃用生物柴油的柴油机颗粒物以及多环芳香烃的影响研究

为探究降低柴油机微粒及多环芳香烃的有效排放控制措施,在一台燃用生物柴油的增压多缸柴油机上应用连续再生微粒捕集器系统,研究了柴油机燃用生物柴油及采用连续再生微粒捕集器系统后对柴油机微粒和多环芳香烃排放的影响。研究结果显示:柴油机微粒排放呈现核态与聚集态形式并且粒子粒径呈现多峰值化特征,燃用生物柴油对核态微粒粒径浓度影响不大,而聚集态微粒排放则有着较为明显的下降趋势,采用连续再生颗粒捕集器后最大下降幅度达到94.6%。柴油机微粒排放中核态粒子浓度占60%以上,燃用生物柴油后该值进一步提升,在试验工况下最大可达到95%。连续可再生微粒捕集器对聚集态粒子捕集效率高,最高可达到96%,试验用柴油机使用生物柴油后,由于核态颗粒数量浓度的提升致使捕集器系统效率有所下降。燃用生物柴油可有效降低绝大部分的多环芳香烃的排放,但测试结果显示:和苯芘蒽排放不降反升,与连续可再生微粒捕集器系统结合,能让菲、芘、苯芘等6种物质排放下降幅度更大。     

非直喷式增压柴油机燃用生物柴油的性能与排放特性

研究了非直喷式增压柴油机燃用柴油一生物柴油混合燃料的性能和排放特性。未对原机作任何调整和改动，研究了不同生物柴油掺混比例的混合燃料对功率、油耗、烟度和NOx排放的影响。结果表明：非直喷式柴油机燃用生物柴油后柴油机功率略有下降，油耗有所上升，烟度大幅下降，NOx排放增加明显。油耗、烟度和NOx的变化均与生物柴油掺混比例呈线性关系，合适的生物柴油掺混比例即可以保持柴油机的性能，又可有效地降低碳烟排放，且不引起NOx排放的显著变化。对于该增压柴油机，掺混生物柴油对外特性下的排放影响最大，影响最小的为标定转速下的负荷特性。不论是全负荷还是部分负荷，燃用生物柴油时低速下的烟度降低和NOx上升幅度均比高速时大，而同转速下高负荷时烟度降低和NOx上升更为明显。     

新型生物乳化柴油在柴油机上的ESC试验研究

在高压共轨电控柴油机上分别燃用柴油(D)、甲酯(B100)和生物乳化柴油(EB10、EB15和EB20)，进行ESC十三工况稳态测试循环试验，研究了生物乳化柴油中水和丁醇含量对发动机燃烧、动力性、经济性和排放的影响。结果表明:5种油品中EB10的放热率峰值最大;随着生物乳化柴油中丁醇和水掺混比例的增大，其滞燃期延长，燃烧持续期缩短；EB10的有效热效率高于柴油，燃油消耗率低于柴油，EB15和EB20与之相反。NO_x、PM排放及烟度随水和丁醇掺混比例增大而降低，HC和 CO排放都有上升趋势但很微小；EB10、EB15和EB20的HC排放略高于柴油，CO排放低于柴油。     

直喷式柴油机燃用生物柴油燃烧特性的研究

研究了柴油机燃用0#柴油和生物柴油的燃烧放热规律。通过对燃烧特征参数的计算分析,发现生物柴油的燃烧始点有所提前,滞燃期缩短;燃烧初期放热尖峰出现时刻对应的曲轴转角有所提前,瞬时放热率峰值下降;燃烧持续期延长。同时还比较了柴油机燃用生物柴油和0#柴油的经济性和排放特性,发现燃油消耗率上升12％左右,而各种排放污染物除NOx略有上升外,CO、HC和颗粒物(PM)均显著下降。     

低配比GTL柴油和生物柴油的燃烧颗粒排放特性

以一台电控高压共轨柴油机为样机,研究了柴油机分别燃用低配比天然气合成油(GTL柴油)、低配比生物柴油混合燃料的颗粒排放特性。所用燃料分别为纯柴油、GTL柴油体积掺混比为10%的燃料(G10)、生物柴油体积掺混比10%的燃料(B10)。研究了该机燃用这三种燃料的烟度、颗粒数量及粒径分布特性。研究结果表明:柴油机燃用G10燃料、B10燃料的排气烟度均低于纯柴油,B10燃料的排气烟度低于G10燃料;柴油燃用三种燃料的排气颗粒数量大多呈明显的单峰或者双峰对数分布。B10燃料的核态颗粒数量在各工况下均为最高,G10燃料在各负荷下全粒径范围内聚集态颗粒与核态颗粒的数量几乎均为最低。随负荷增加,柴油机颗粒总数量呈总体上升趋势。各工况下,柴油机燃用B10燃料的颗粒总数量最高,G10燃料的颗粒总数量最低,核态颗粒数量的差异在其中占主导地位。     

发动机燃用柴油和二甲醚时颗粒排放对比研究

采用电子低压撞击仪(ELPI)和HORIBA MDLT-1302部分流稀释采样颗粒排放质量测量系统,研究了2102QB发动机分别燃用柴油和二甲醚(DME)时颗粒排放(PM)的粒径分布及质量排放特性。试验结果表明:发动机燃用柴油时,PM主要是粒径为0.05~0.30μm的积聚态粒子,而燃用DME时则主要为粒径在0.05μm以下的核模态粒子;柴油机PM的颗粒数浓度比燃用DME时高1~2个数量级;随着转速的增加,发动机燃用两种燃料时的PM的颗粒数浓度均增加,DME发动机的质量浓度也增加,但柴油机的质量浓度降低;柴油机排气颗粒数浓度和质量浓度随负荷增加均升高,尤其在高负荷段急剧增加。DME发动机排气颗粒质量浓度随着T_(tq)·exp(n/1000)值的增加而先增加后降低,呈现明显的单峰曲线,且各转速下峰值位置基本相同。除全速低负荷工况外,发动机在部分负荷工况下,燃用DME时PM质量浓度为燃用柴油时的0.44%~16.6%,全负荷工况下为0.44%~0.98%。     

Experimental investigations on combustion, performance and emissions characteristics of neat karanji biodiesel and its methanol blend in a diesel engine

The increased focus on alternative fuels research in the recent years are mainly driven by escalating crude oil prices, stringent emission norms and the concern on clean environment. The processed form of vegetable oil (biodiesel) has emerged as a potential substitute for diesel fuel on account of its renewable source and lesser emissions. The experimental work reported here has been carried out on a turbocharged, direct injection, multi-cylinder truck diesel engine fitted with mechanical distributor type fuel injection pump using biodiesel-methanol blend and neat karanji oil derived biodiesel under constant speed and varying load conditions without altering injection timings. The results of the experimental investigation indicate that the ignition delay for biodiesel-methanol blend is slightly higher as compared to neat biodiesel and the maximum increase is limited to 1 deg. CA. The maximum rate of pressure rise follow a trend of the ignition delay variations at these operating conditions. However, the peak cylinder pressure and peak energy release rate decreases for biodiesel-methanol blend. In general, a delayed start of combustion and lower combustion duration are observed for biodiesel-methanol blend compared to neat biodiesel fuel. A maximum thermal efficiency increase of 4.2% due to 10% methanol addition in the biodiesel is seen at 80% load and 16.67 s⁻¹ engine speed. The unburnt hydrocarbon and carbon monoxide emissions are slightly higher for the methanol blend compared to neat biodiesel at low load conditions whereas at higher load conditions unburnt hydrocarbon emissions are comparable for the two fuels and carbon monoxide emissions decrease significantly for the methanol blend. A significant reduction in nitric oxide and smoke emissions are observed with the biodiesel-methanol blend investigated.     

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)。     

Effect of metal based additive on performance emission and combustion characteristics of diesel engine fuelled with biodiesel

This study investigates the use of ferric chloride (FeCl₃) as a fuel borne catalyst (FBC) for waste cooking palm oil based biodiesel. The metal based additive was added to biodiesel at a dosage of 20 μmol/L. Experiments were conducted to study the effect of ferric chloride added to biodiesel on performance, emission and combustion characteristics of a direct injection diesel engine operated at a constant speed of 1500 rpm at different operating conditions. The results revealed that the FBC added biodiesel resulted in a decreased brake specific fuel consumption (BSFC) of 8.6% while the brake thermal efficiency increased by 6.3%. FBC added biodiesel showed lower nitric oxide (NO) emission and slightly higher carbon dioxide (CO₂) emission as compared to diesel. Carbon monoxide (CO), total hydrocarbon (THC) and smoke emission of FBC added biodiesel decreased by 52.6%, 26.6% and 6.9% respectively compared to biodiesel without FBC at an optimum operating condition of 280 bar injection pressure and 25.5^o bTDC injection timing. Higher cylinder gas pressure, heat release rate and shorter ignition delay period were observed with FBC added biodiesel at these conditions.     

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。     

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.     

Effect of hydrogen enrichment in the intake air of diesel engine fuelled with honge biodiesel blend and diesel

In the current investigation, the enrichment of hydrogen with the honge biodiesel blend and diesel is used in a compression ignition engine. The biodiesel is derived from the honge oil and mixed with diesel fuel by 20% (v/v). Thereafter, hydrogen at different volume flow rates (10 and 13 lpm) is introduced into the intake manifold. The outcomes by enrichment of hydrogen on the performance, combustion and emission characteristics are investigated by examining the brake thermal efficiency, fuel consumption, HC, CO, CO₂, NOₓ emissions, in-cylinder pressure, combustion duration, and rate of heat release. The engine fuelled with honge biodiesel blend is found to enhance the thermal efficiency, combustion characteristics. Compare to diesel, the BTE increased by 2.2% and 6% less fuel consumption for the HB20 + 13H₂ blend. Further, reduction in the emission of exhausts gases like CO and HC by 21% and 24%, respectively, are obtained. This is due to carbon-free structure in hydrogen. Moreover, due to high pressure in the cylinder, there is a slight increase in oxides of nitrogen emission compare to diesel. The combustion characteristics such as rate of heat release, combustion duration, and maximum ₂rate of pressure rise and in-cylinder pressure are high due to hydrogen.     

Effect of fuel opening injection pressure and injection timing of hydrogen enriched rice bran biodiesel fuelled in CI engine

Fuel opening injection pressure and injection timing are important injection parameters, and they have a significant influence on engine combustion, performance, and emissions. The focus of this work is to improve the performance and emissions of single-cylinder diesel engines by using injection parameters in engines running with rice bran biodiesel 10% blend (RB10+H₂) and 20% blend (RB20+H₂) with a fixed hydrogen flow rate of 7 lpm. In addition, hydrogen and biodiesel are excellent alternatives to conventional fuels, which can reduce energy consumption and strict emission standards. The investigation is conducted for three different opening injection pressure of 220, 240, 260 bar, and four different injection timings of 20°, 22°, 24°, and 26° bTDC. Results indicate that the sample ‘RB10+H₂’ provides 3.32% higher BTE and reduces the fuel consumption by 13% as diesel fuel. The blend RB10+H₂ attributes a maximum cylinder pressure of 68.7 bar and a peak HRR value of 49 J/ºCA. Further, compared to diesel, RB10+H₂ blend emits lower CO, HC, and smoke opacity by 17%, 22%, and 16%, respectively. However, an almost 12% increase of nitrogen oxides for the RB10+H₂ blend is observed. However, with advanced injection timing and higher opening injection pressure, NOx emissions is slightly increased.     

A study on the effect of hydrogen enriched intake air on the characteristics of a diesel engine fueled with ethanol blended diesel

This work aims to replace conventional diesel fuel with low and no carbon fuels like ethanol and hydrogen to reduce the harmful emission that causes environmental degradation. Pursuant to this objective, this study investigated the performance, combustion, and emission characteristics of the diesel engine operated on dual fuel mode by ethanol-diesel blends with H₂ enriched intake air at different engine loads with a constant engine speed of 1500 rpm. The results were compared to sole diesel operation with and without H₂ enrichment. The ethanol/diesel was blended in v/v ratios of 5, 10, and 15% and tested in a diesel engine along with a 9 lpm H₂ flow rate at the intake manifold. The results revealed that 10% ethanol with 9 lpm H₂ combination gives the maximum brake thermal efficiency, which is 1% and 4.8% higher than diesel with and without H₂ enrichment, respectively. The brake specific fuel consumption of the diesel-ethanol blends with H₂ flow increased with increasing ethanol ratio in the blend. When the ethanol ratio increased from 5 to 10%, in-cylinder pressure and heat release rate were increased, whereas HC, CO, and NO_x emissions were decreased. At maximum load, the CO and HC emission of 10% ethanol blend with 9 lpm H₂ case decreased by about 50% and 28.7% compared to sole diesel. However, NO_x emission of the same blend was 11.4% higher than diesel. From the results, the study concludes that 10% ethanol blended diesel with a 9 lpm H₂ flow rate at the intake port is the best dual-fuel mode combination that gives the best engine characteristics with maximum diesel replacement.     

The experimental study on the performance,combustion and emission characteristics of a diesel engine using diesel – biodiesel – diethyl ether blends

ABSTRACT

In the present research work, the experimental analysis has been executed to investigate the influence of diethyl ether as an oxygenated additive to the diesel-biodiesel blend on the performance, combustion and emission characteristics of a diesel engine. The biodiesel (Frying oil methyl ester) was prepared by the transesterification process, and the biodiesel was added (40% by volume) to the diesel fuel to prepare the diesel-biodiesel blend (D60FME40). The diethyl ether was added to the diesel-biodiesel blends D60FM35 (diesel 60% + biodiesel 35% by volume) and D60FM30 (diesel 60% + biodiesel 30% by volume) with suitable volume proportions of 5% and 10% respectively to form diesel-biodiesel-diethyl ether blends ((D60FM35DEE5) & (D60FM30DEE10)). Initially, the test was conducted with diesel fuel to obtain the baseline reference reading. Then, the reading was compared with results taken from the engine using a diesel-biodiesel blend (D60FME40) and diethyl ether blends (D60FM35DEE5) & (D60FM30DEE10). The results reveal that the maximum brake thermal efficiency was obtained with diesel fuel and it was higher than the diesel-biodiesel blend and diethyl ether blends. The peak in-cylinder gas pressure and heat release rate in the premixed stage was less for the diesel-biodiesel blend, but it was increased with the addition of diethyl ether to the blend. The diesel-biodiesel-diethyl ether blends show less carbon monoxide and hydrocarbon emissions except for NO_X emission as compared to the diesel and diesel-biodiesel blend, especially at the engine rated power.