Effects of Fischer-Tropsch diesel fuel on combustion and emissions of direct injection diesel engine

Effects of Fischer-Tropsch (F-T) diesel fuel on the combustion and emission characteristics of a single-cylinder direct injection diesel engine under different fuel delivery advance angles were investigated. The experimental results show that F-T diesel fuel exhibits shorter ignition delay, lower peak values of premixed burning rate, lower combustion pressure and pressure rise rate, and higher peak value of diffusion burning rate than conventional diesel fuel when the engine remains unmodified. In addition, the unmodified engine with F-T diesel fuel has lower brake specific fuel consumption and higher effective thermal efficiency, and presents lower HC, CO, NO _x and smoke emissions than conventional diesel fuel. When fuel delivery advance angle is retarded by 3 crank angle degrees, the combustion duration is obviously shortened; the peak values of premixed burning rate, the combustion pressure and pressure rise rate are further reduced; and the peak value of diffusion burning rate is further increased for F-T diesel fuel operation. Moreover, the retardation of fuel delivery advance angle results in a further significant reduction in NO _x emissions with no penalty on specific fuel consumption and with much less penalty on HC, CO and smoke emissions. __________ Translated from Chinese Internal Combustion Engine Engineering, 2007, 28(2): 19–23 [译自: 内燃机工程]     

柴油机燃用F-T柴油与0号柴油混合燃料的燃烧特性

根据实测的喷油器针阀升程和示功图,开展了直喷式柴油机燃用F-T柴油与0号柴油混合燃料时燃烧特性的研究．试验用燃料为0号柴油、含25%和50%F-T柴油的混合燃料以及100%F-T柴油．结果表明,在相同工况下,随着混合燃料中F-T柴油比例的增加,喷油延迟角增大,而喷油持续期变化不大．滞燃期随着F-T柴油比例的增加而缩短,其中当F-T柴油的比例由0增至25%时,滞燃期缩短最为明显,此后进一步增加F-T柴油的比例,滞燃期缩短幅度减小．随着混合燃料中F-T柴油比例的增加,预混燃烧放热峰值降低,扩散燃烧放热峰值增大,燃烧持续期略有延长,缸内最高燃烧压力和气体最高平均温度降低,最大压力升高率显著下降,发动机的燃烧噪音和机械损失减小,有效燃油消耗率和有效热效率得到改善．     

Emission characteristics of a turbocharged diesel engine fueled with gas-to-liquids

Emission characteristics of a turbocharged, intercooled, heavy-duty diesel engine operating on neat gas-to-liquids (GTL) and blends of GTL with conventional diesel were investigated and a comparison was made with those of diesel fuel. The results show that nitrogen oxides (NO _x ), smoke, and particulate matter (PM) emissions can be decreased when operating on GTL and diesel-GTL blends. Engine emissions decrease with an increase of GTL fraction in the blends. Compared with diesel fuel, an engine operating on GTL can reduce NO _x , PM, carbon monoxide (CO), and hydrocarbon (HC) by 23.7%, 27.6%, 16.6% and 12.9% in ECE R49 13-mode procedure, respectively. Engine speed and load have great influences on emissions when operating on diesel-GTL blends and diesel fuel in the turbocharged diesel engine. The study indicates that GTL is a promising alternative fuel for diesel engines to reduce emissions. Translated from Transactions of CSICE, 2006, 24(6): 489–493 [译自: 内燃机学报]     

F-T柴油对直喷式柴油机燃烧和排放的影响

在两种不同供油提前角下研究了燃用F-T柴油对直喷式柴油机燃烧和排放特性的影响,结果表明:发动机不做任何调整时,与0号柴油相比,燃用F-T柴油的滞燃期较短,预混燃烧放热峰值较低,扩散燃烧放热峰值较高,最高燃烧压力和最大压力升高率较低,燃油消耗率和热效率都得到了改善,HC、CO、NOx和碳烟排放同时降低。当供油提前角推迟3℃A时,燃用F-T柴油燃烧持续期明显缩短,预混燃烧放热峰值、最高燃烧压力和最大压力升高率进一步降低,扩散燃烧放热峰值略有升高,燃油消耗率变化不大,NOx排放进一步降低, HC、CO和碳烟略有增加,其中HC排放与原柴油机相当,而CO和碳烟仍远低于原柴油机。     

高原地区柴油机燃用生物柴油混合燃料排放特性研究

在高原环境（81kPa）下,对4100QBZL型柴油机燃用不同配比生物柴油混合燃料后的排放特性进行了实验研究。实验结果表明：与燃用柴油相比,各工况下,HC、CO和碳烟的排放均有不同程度的降低（分别平均下降4．5％～38．4％、15．4％～43．9％和12．5％～65．5％）,高负荷低转速工况下效果尤为明显;NOx的排放也得到明显改善,只有纯生物柴油的NO。排放较柴油上升了0％～2．1％,其他指标均下降（平均下降4．4％～4．9％）。综合考虑,燃用掺混比为30％以内的生物柴油混合燃料,能同时有效地降低HC、CO、NOx和碳烟的排放。     

直喷式柴油机燃用生物柴油的燃烧特性

在一台直喷式增压柴油机上进行了生物柴油、柴油及其掺混油B20、B50的性能试验,通过测量喷油器针阀升程、喷油压力和气缸压力曲线,对放热率、滞燃期等燃烧特性参数进行了分析,以研究生物柴油对发动机燃烧性能的影响。试验结果表明,在相同工况下,随着掺混油中生物柴油比例的增加,喷油始点逐渐提前,喷油延迟角逐渐变大,喷油压力和喷油持续期有所增加;滞燃期逐渐缩短,在大负荷尤为明显;预混合放热峰值逐渐降低,而扩散燃烧放热峰值逐渐增大;缸内最高燃烧压力提高,其对应的曲轴转角也逐渐提前。燃用生物柴油后发动机的热效率有所提高,在中等负荷时尤为明显。     

燃用小桐子油柴油机怠速工况工作过程及循环波动

采用柴油、柴油-小桐子掺混油、小桐子油、高温小桐子油,在单缸水冷四冲程柴油机上进行了怠速工况试验,测录了多循环的瞬时气缸压力与高压油管燃油压力,对比分析了喷油与燃烧过程中各参数的循环波动。结果发现,怠速工况喷油过程中,喷油持续期的循环波动最明显,小桐子油的喷油始点滞后,喷油持续期长,喷油压力大,喷油过程的循环波动略大;怠速工况燃烧过程中,最大燃烧压力升高率和滞燃期的循环波动率最为明显,小桐子油滞燃期略短,燃烧压力升高率小,最高燃烧压力低,滞燃期和最大燃烧压力升高率的循环波动明显大于柴油;燃用小桐子油增大了原机的循环波动,怠速运转不如柴油稳定。     

直喷式柴油机燃用F-T柴油时的性能与排放

煤通过Fischer-Tropsch（F-T）合成可以获得十六烷值高、硫和芳香烃含量极低的F-T柴油.在一台未作改动的单缸直喷式柴油机上对燃用F-T柴油时发动机的性能和排放进行了研究.结果表明,在相同工况下与燃用常规柴油相比,燃用F-T柴油时的滞燃期较短,预混燃烧放热峰值较低,扩散燃烧放热峰值较高,最高燃烧压力略低,最大压力升高率显著下降,燃油消耗率和热效率都得到了改善.燃用F-T柴油可同时降低CO、HC、NOx和碳烟排放,其中NOx和碳烟排放分别平均降低了16.7%和40.3%.研究表明F-T柴油是柴油机优秀的清洁代用燃料.     

甲醇预混合气F-T柴油引燃模式下发动机燃烧特性研究

为了提高甲醇在能量转化效率方面的优势,在一台CY25TQ型柴油机上,利用F-T柴油和煤基甲醇研究了甲醇占能比、F-T柴油喷油时刻对甲醇预混合气F-T柴油引燃燃烧方式下发动机燃烧特性的影响。试验结果表明:甲醇占能比增加,此燃烧方式滞燃期、持续期波动较大。在平均有效压力为0.45MPa下,缸内最大压力、瞬时放热率峰值、最大压力升率明显降低,最大降幅分别为26.40%、59.25%和58.00%。高负荷时,不同甲醇占能比下F-T柴油喷射时刻调整,能促进压升率进一步降低。与原柴油机扩散燃烧方式相比,虽然采用引燃喷射的双燃料发动机在中低负荷时的有效热效率有所降低,但是随着负荷增加,高负荷下的热效率比原柴油机高,最大提高了17.14%。     

Combustion and emission characteristics of a spray guided direct-injection spark-ignition engine fueled with natural gas-hydrogen blends

Combustion and emission characteristics of a spray guided direct-injection spark-ignition engine fueled with natural gas-hydrogen blends were investigated. Results show that the brake thermal efficiency increases with the increase of hydrogen fraction and it shows an increasing and then decreasing trend with advancing fuel-injection timing. For later injection timings, the beginning of heat release is advanced with increasing hydrogen fraction, while the beginning of heat release is advanced and then retarded with the increase of hydrogen fraction at earlier injection timings. The flame development duration, rapid combustion duration and total combustion duration decrease with increasing hydrogen fraction. Maximum cylinder gas pressure, maximum mean gas temperature, maximum rate of pressure rise and maximum heat release rate show an increasing and then decreasing trend with the increase of hydrogen fraction. Brake NOx emission is increased and then decreased, while brake HC, CO and CO₂ emissions decrease with the increase of hydrogen fraction.     

Combustion characteristics of SI engine fueled with methanol-gasoline blends during cold start

A 3-cylinder port fuel injection (PFI) engine fueled with methanol-gasoline blends was used to study combustion and emission characteristics. Cylinder pressure analysis indicates that engine combustion is improved when methanol is added to gasoline. With the increase of methanol, the flame developing period and the rapid combustion period are shortened, and the indicated mean effective pressure increases during the first 50 cycles. Meanwhile, a novel quasi-instantaneous sampling system was designed to measure engine emissions during cold start and warm-up. The results at 5°C show that unburned hydrocarbon (UHC) and carbon monoxide (CO) decrease remarkably. Hydrocarbon (HC) reduces by 40% and CO by 70% when fueled with M30 (30% methanol in volume). The exhaust gas temperature is about 140°C higher at 200 s after operation compared with that of gasoline. __________ Translated from Transactions of CSICE, 2007, 25(3): 235–240 [译自: 内燃机学报]     

缸内直喷灵活燃料发动机性能和燃烧特性的研究

根据所测的示功图和排放结果,分析了一台采用火花点火、缸内直喷周向分层燃烧系统,能够灵活燃用甲醇、乙醇和汽油的发动机的性能和燃烧特性.研究表明,由于采用分层燃烧,灵活燃料发动机具有与直喷柴油机相当的热效率,在负荷特性上,燃用醇类燃料和汽油时的NOx排放分别仅为柴油机的10%～40%和21%～78%,CO排放低于1%,HC排放略高于柴油机,燃用醇类燃料时能实现无烟燃烧,燃用汽油时仅在高负荷时存在少许碳烟.灵活燃料发动机的燃烧由预混燃烧与扩散燃烧组成,具有非常快的燃烧速率,上止点后3～5°CA就燃烧完50%燃料,燃烧持续期在28～37°CA范围内,甲醇的燃烧速率最快,汽油的燃烧速率在低负荷时比乙醇稍快,在高负荷时比乙醇慢.     

Performance and combustion characteristic of CI engine fueled with hydrogen enriched diesel

The combustion of hydrogen–diesel blend fuel was investigated under simulated direct injection (DI) diesel engine conditions. The investigation presented in this paper concerns numerical analysis of neat diesel combustion mode and hydrogen enriched diesel combustion in a compression ignition (CI) engine. The parameters varied in this simulation included: H₂/diesel blend fuel ratio, engine speed, and air/fuel ratio. The study on the simultaneous combustion of hydrogen and diesel fuel was conducted with various hydrogen doses in the range from 0.05% to 50% (by volume) for different engine speed from 1000 – 4000 rpm and air/fuel ratios (A/F) varies from 10 – 80. The results show that, applying hydrogen as an extra fuel, which can be added to diesel fuel in the (CI) engine results in improved engine performance and reduce emissions compared to the case of neat diesel operation because this measure approaches the combustion process to constant volume. Moreover, small amounts of hydrogen when added to a diesel engine shorten the diesel ignition lag and, in this way, decrease the rate of pressure rise which provides better conditions for soft run of the engine. Comparative results are given for various hydrogen/diesel ratio, engine speeds and loads for conventional Diesel and dual fuel operation, revealing the effect of dual fuel combustion on engine performance and exhaust emissions.     

Experimental investigation of the influence of blending on engine emissions of the diesel engine fueled by mahua biodiesel oil

The present article elaborates on the various emission characteristics of mahua oil with diesel fuel in a diesel engine at various blending conditions. Experimental investigation results are studied for various parameters such as exhaust emission of carbon monoxide (CO), hydrocarbon (HC), and oxides of nitrogen (NO) gases and exhaust gas temperature. Results show that residual oxygen, CO, HC, and NO emission were the lowest for mahua biodiesel compared with diesel. The experimental results proved that the use of mahua oil biodiesel as fuel in the diesel engine is a viable alternative to diesel fuel. Mahua biodiesel oil may be beneficial in decreasing greenhouse gas emissions without any engine modification. Mahua oil has the possibility of becoming a sustainable fuel source as biodiesel.     

柴油机燃用F-T柴油与0号柴油混合燃料时的性能与排放

开展了直喷式柴油机燃用F-T柴油与0号柴油混合燃料时性能与排放的研究,试验用燃料为0号柴油、含25%和50%F-T柴油的混合燃料以及100%F-T柴油。结果表明,在相同工况下,随着混合燃料中F-T柴油比例的增加,滞燃期缩短,预混燃烧放热峰值降低,扩散燃烧放热峰值增大,最高燃烧压力略微降低,发动机的燃油消耗率和有效热效率得到改善。在负荷特性上,发动机的CO_2、HC、CO、NO_x和碳烟排放随着F-T柴油的加入而降低,其中CO和碳烟在中高负荷时降低幅度最为显著。当F-T柴油掺混比例由0增至25%时,碳烟排放降低效果最为明显,此后随着F-T柴油的继续增加,碳烟排放降低幅度减少。     

Gas emissions and particulate matter of non-road diesel engine fueled with F-T diesel with EGR

The gas emissions and particulate matter of non-road diesel engine fueled with Fischer–Tropsch diesel fuel were investigated. The test was carried out on a four-stroke, water-cooled, single-cylinder engine under different the exhaust gas recirculation (EGR) rates such as 0%, 15%, and 30% at 2,700 rpm, 25%, 50%, and 75% load. The test results showed that when the EGR rate is less than 15%, nitrogen oxides (NO_x) are reduced significantly, while hydrocarbon (HC) and carbon monoxide (CO) are increased less than 5%. However, when the EGR rate was 30%, HC and CO were maximally increased to 13.2% and 13.3%, respectively. Additionally, the Field Emission Scanning Electronic Microscope test and Energy Dispersive Spectrometer test were conducted. With increase of EGR rates, the micromorphology of particles was mainly showed as chain-like status and the growth of number concentration of particle was mainly contributed by the nuclear particle when the engine was at 25% load. In contrast, the micromorphology of particles was principally showed as clustered-like status, and the aggregated particles were dominating growth at 50% and 75% load. Moreover, as EGR rates increased, the degree of agglomeration and carbon content were gradually decreased at 25% load. The test also showed the opposite tendency at 50% and 75% load.     

Pressure–time characteristics in diesel engine fueled with natural gas

Combustion pressure data are measured and presented for a dual fuel engine running on dual fuel of diesel and compressed natural gas, and compared to the diesel engine case. The maximum pressure rise rate during combustion is presented as a measure of combustion noise. Experimental investigation on diesel and dual fuel engines revealed the noise generated from combustion in both cases. A Ricardo E6 diesel version engine is converted to run on dual fuel of diesel and compressed natural gas and is used throughout the work. The engine is fully computerized and the cylinder pressure data, crank angle data are stored in a PC for off-line analysis. The effect of engine speeds, loads, pilot injection angle, and pilot fuel quantity on combustion noise is examined for both diesel and dual engine. Maximum pressure rise rate and some samples of ensemble averaged pressure–crank angle data are presented in the present work. The combustion noise, generally, is found to increase for the dual fuel engine case as compared to the diesel engine case.     

Emission analysis of diesel engine fueled with soybean biodiesel and its water blends

The present study is carried out to formulate stable water-in-soybean biodiesel emulsion fuel and investigate its emission characteristics in a single cylinder diesel engine. Four types of emulsion fuels, which consist of a different percentage of water (5%, 10%, 15%, and 20%) in soybean biodiesel, were prepared with suitable surfactant and properties were measured. The physicochemical properties are on par with EN 14214 standards. The experimental result of test fuels indicates that the soybean biodiesel promotes a lower level of hydrocarbon (HC), carbon monoxide (CO) and smoke emissions compared to base diesel except for nitrogen oxide (NOx) emission. Increase in water concentration with soybean biodiesel significantly reduces the NOx emission and smoke opacity. The HC and CO emissions are further reduced with emulsified biodiesel up to 10% water concentration and beyond that limit, marginal increases are recorded. Overall, it is observed that inclusion of water with soybean biodiesel reduces the HC, CO, NOx and smoke emissions when compared to base diesel and soybean biodiesel, and 10% water in soybean biodiesel is an appropriate solution to reduce the overall emissions in the soybean-fuelled diesel engine.     

Influence of advanced injection timing on the performance and emissions of CI engine fueled with ethanol‐blended diesel fuel

Ethanol has been considered as an alternative fuel for diesel engines. On the other hand, injection timing is a major parameter that sensitively affects the engine performance and emissions. Therefore, in this study, the influence of advanced injection timing on the engine performance and exhaust emissions of a single cylinder, naturally aspirated, four stroke, direct injection diesel engine has been experimentally investigated when using ethanol‐blended diesel fuel from 0 to 15% with an increment of 5%. The original injection timing of the engine is 27° crank angle (CA) before top dead center (BTDC). The tests were conducted at three different injection timings (27, 30 and 33° CA BTDC) for 30 Nm constant load at 1800 rpm. The experimental results showed that brake‐specific energy consumption (BSEC), brake‐specific fuel consumption (BSFC), NO_x and CO₂ emissions increased as brake‐thermal efficiency (BTE), smoke, CO and HC emissions decreased with increasing amount of ethanol in the fuel mixture. Comparing the results with those of original injection timing, NO_x emissions increased and smoke, HC and CO emissions decreased for all test fuels at the advanced injection timings. For BSEC, BSFC and BTE, advanced injection timings gave negative results for all test conditions. Copyright © 2008 John Wiley & Sons, Ltd.     

Combustion characteristics of a stationary diesel engine fuelled with a blend of crude rice bran oil methyl ester and diesel

The objective of the present work is to analyze the combustion characteristics of crude rice bran oil methyl ester (CRBME) blend (20% of CRBME with 80% no.2 diesel on volume basis) as a fuel in a stationary small duty direct injection (DI) compression ignition (CI) engine. When operating with CRBME blend the cylinder pressure was comparable to that of diesel. It was observed that the delay period and the maximum rate of pressure rise for CRBME blend were lower than those of diesel. The occurrence of maximum heat release rate advanced for CRBME blend with lesser magnitude when compared to diesel. CRBME blend requires more crank angle duration to release 50% & 90% of heat when compared with diesel. The brake specific fuel consumption of CRBME blend was found to be only marginally different from that of the diesel and its hourly fuel cost was higher than that of diesel. CRBME blend has lower smoke intensity and higher NOx emission than those of diesel. Since the measured parameters for CRBME blend differs only by a smaller magnitude, when compared with diesel, this investigation ensures the suitability of CRBME blend as fuel for CI engines with higher fuel cost.