PODE掺混和喷油参数对柴油机燃烧排放特性影响

在一台增压4缸直喷柴油机上开展了不同聚甲基二甲醚(PODE)掺混比例和喷油参数对柴油机燃烧和排放特性影响的试验.测试燃料包括纯柴油(PD0)、两种柴油/PODE混合燃料分别为PD20(PODE体积分数为20%)和PD30(PODE体积分数为30%).结果表明:随着喷油时刻的推迟,3种燃料缸内压力峰值降低,放热率峰值增加,燃油消耗率增加,热效率下降,CO和HC排放增加,NOx排放减小,颗粒物质量浓度降低,数量浓度先降低后升高;随喷油压力的增加,3种燃料缸内压力和放热率峰值增加,CO和HC排放减小,NOx排放增加,颗粒物数浓度和质量浓度下降.喷油时刻推迟和喷油压力增加都会使PD0的烟度排放明显减少,但对PD20和PD30的烟度排放影响比较小.随着PODE比例增加,热效率提高,但燃油消耗率上升,CO、HC和烟度排放下降,NOx排放小幅增加,颗粒物数浓度和质量浓度显著降低.     

煤基柴油及其混合燃料对发动机燃烧与排放的影响

对一台高压共轨增压中冷压燃式发动机燃用煤基F-T合成柴油(CTL)及其与碳酸二甲酯(DMC)的混合燃料进行了燃烧和排放特性试验,揭示了燃料特性和排气再循环对燃烧过程、NOx及微粒排放的影响规律.结果表明:发动机燃用CTL时的有效热效率升高,燃烧过程中滞燃期较短,预混合燃烧量减少,压力升高率明显降低,有利于改善柴油机工作的平顺性.与国V石化柴油相比,燃用CTL燃料时消光烟度、核态微粒、超细微粒及总微粒数量浓度明显降低,积聚态微粒数量浓度略有增加,有利于同时降低微粒质量和数量排放.引入排气再循环(EGR)可以进一步降低CTL燃料的NOx排放,在EGR率达到30%,时,NOx排放降低近75%,.在CTL中添加含氧燃料DMC,有利于抑制EGR导致的烟度增加,与国V柴油相比,在EGR率为30%,条件下,D15燃料消光烟度和微粒总数量的降幅分别为69.1%,和53.9%,.燃用CTL/DMC混合燃料同时引入EGR可以同时降低NOx、消光烟度、微粒质量和数量排放,有利于缓解柴油机NOx和PM之间的矛盾关系.     

引燃柴油量对甲醇/柴油双燃料发动机性能和排放的影响

在一台TY1100型直喷柴油机上,开展了引燃柴油量对柴油引燃甲醇双燃料发动机性能和排放影响的研究。试验结果表明:引燃柴油比例为28.9%~48.2%时,发动机可获得较好的动力性,甲醇质量掺比可达73.3%~83.2%。与原柴油机相比,双燃料发动机的碳烟排放大幅度下降,NOx排放降低,而HC和CO排放增加。高负荷时发动机有效热效率增加而CO排放基本相当。在同一引燃柴油量下,HC排放呈先增加后减少的趋势,增加引燃柴油量,可以提高发动机低负荷时的有效热效率和降低HC排放,但在全负荷时,会导致NOx排放增加。     

供油提前角对柴油/甲醇混合燃料燃烧排放性能的影响

添加助溶剂并使用超声波振动形成混合均匀的柴油/甲醇混合燃料,通过柴油机台架试验,分析供油提前角变化对柴油/甲醇混合燃料燃烧排放的影响。试验结果表明:供油提前角提前,柴油/甲醇混合燃料的有效燃油消耗率降低。随着供油提前角减小,混合燃料滞燃期缩短,供油提前角为21°CA时,混合燃料的燃烧持续期最短,增加或减少供油提前角都将延长燃烧持续期。供油提前角变化对柴油/甲醇混合燃料的排放有较大影响,推迟供油,混合燃料的烟度排放和CO排放增加,NOx排放与HC排放降低。     

柴油机燃用生物柴油的排放特性研究

生物柴油来自于动植物油脂的单酯衍生物,是一种可再生的替代能源。脂肪酸单酯作为发动机燃料的可行性来自于其分子结构和较高的能量密度。柴油机燃用生物柴油与0^#柴油具有几乎一致的热效率。在同一稳定工况下,随着生物柴油加入比例的增加,生物柴油与0^#柴油混合燃料燃烧产生的排放物中CO和HC比排放呈现线性下降,NOx比排放有所增加,而CO2比排放维持在同一水平。     

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.     

柴油/正戊醇/甲醇三元微乳化燃料柴油机燃烧与排放特性研究

为了使柴油与甲醇互溶,提高燃料氧含量以控制碳烟排放,以正戊醇作为助溶剂,形成柴油/正戊醇/甲醇三元微乳化燃料,对三元燃料在不同温度下的互溶性进行了研究。在一台电控高压共轨柴油机上测试了1 400r/min转速下柴油/正戊醇/甲醇三元微乳化燃料的燃烧压力和排放特性;计算了瞬时燃烧放热率与燃烧温度,并与柴油进行对比。研究结果表明:甲醇能够以一定比例与柴油/正戊醇互溶,且互溶比例随温度升高而增大。与纯柴油相比,随氧含量的增加,混合燃料的滞燃期延长,燃烧持续期缩短,峰值燃烧温度升高;在中低负荷,峰值燃烧放热率上升;在高负荷,三元微乳化燃料的峰值燃烧放热率下降,但其扩散燃烧强度增加;混合燃料的有效燃油消耗率增加,但是其热值逐渐降低,有效热效率上升;3种含氧燃料的CO排放在低负荷时增加,高负荷时降低;HC及NOx排放升高,NO2在NOx中的比例下降;碳烟排放明显减少。     

压燃式发动机燃用汽油/柴油混合燃料瞬变工况下燃烧及微粒排放特性分析

针对压燃式发动机燃用汽油/柴油混合燃料稳态及瞬态工况下的燃烧及微粒排放粒度分布特征进行了试验研究,分析了汽油掺入比例及EGR对发动机稳态及不同瞬变率的恒转速增转矩瞬变工况超细微粒数量排放的影响规律.结果表明:在大负荷工况下采用高汽油掺入比例的汽油/柴油混合燃料能够在不引起NOx显著增加的前提下进一步降低排气烟度,有助于拓展预混合燃烧过程负荷工况范围;但较高汽油掺入比例易导致油气过度混合,对HC及CO排放有不利影响,尤其会导致小负荷工况下CO排放显著增加.综合考虑不同负荷工况下运行情况,认为汽油掺入比例在40%,~50%,左右较为适宜.燃用汽油/柴油混合燃料时排气颗粒物更趋于细化,其微粒几何平均粒径较柴油明显降低.瞬变工况增负荷过程中,各模态微粒数量浓度均有所升高,随汽油掺入比例增大积聚态微粒数量增加程度变缓,当汽油掺入比例达到50%,时,在高瞬变率工况时积聚态微粒数量无明显增加.高比例EGR条件下,瞬变过程中积聚态微粒数量浓度在增负荷初期便急剧增加,燃用汽油/柴油混合燃料有利于缓解瞬态工况积聚态微粒数量急剧增加的程度.     

甲醇柴油对增压中冷柴油机燃烧与排放性能的影响

针对在增压中冷柴油机上燃用不同比例甲醇柴油对发动机燃烧和排放性能的影响进行了研究。结果表明：随着混合燃料中甲醇含量的增加,发动机动力性略有降低,使用经济性提高,缸内最大压力和温度降低,NOx和碳烟排放降低,HC排放增加;CO排放小负荷下大幅增加而在大负荷下略有降低。     

甲醇/柴油混合燃料柴油机性能试验研究及分析

在一台YC6105型六缸直列直喷柴油机上进行了燃用甲醇/柴油混合燃料对柴油机性能和排放影响的研究。试验结果表明:使用甲醇/柴油混合燃料柴油机具有相对较好的动力输出特性;与使用纯柴油燃料相比,NOx排放大幅下降,碳烟排放明显减少,并对CO排放有很强的抑制作用;对HC排放影响不大,但在高速高负荷时会促进HC生成。     

发动机燃用生物柴油的性能研究

通过对比研究了柴油机燃用餐饮废弃油炼制的生物柴油、柴油及B50时在高原地区的动力性、经济性及排放特性。研究结果表明：在柴油机不进行任何调整的情况下,全负荷时,燃用生物柴油的发动机动力性降低6.8%,B50降低3%;燃用生物柴油有效燃油消耗率升高了13.8%;燃用B50在高速高负荷时柴油机热效率提高2.5%;无论在全负荷还是在部分负荷工况下,燃用生物柴油均能大幅度降低柴油机烟度、CO和HC排放,但会引起NOx排放量的上升。     

Performance and emission characteristics of CIE using hydrogen,biodiesel, and massive EGR

Hydrogen is considered as an excellent energy carrier and can be used in diesel engines that operate in dual fuel mode. Many studies have shown that biodiesel, which is sustainable, clean, and safe, a good alternative to fossil fuel. However, tests have confirmed that using biodiesel or hydrogen as a fuel or added fuel in compression ignition engines increases NOx concentrations. Cooled or hot exhaust gas recirculation (EGR) effectively controls the NOx outflows of diesel engines. However, this technique is restricted by high particulate matter PM emissions and the low thermal efficiency of diesel engines.In this study, gaseous hydrogen was added to the intake manifold of a diesel engine that uses biodiesel fuel as pilot fuel. The investigation was conducted under heavy-EGR conditions. An EGR system was modified to achieve the highest possible control on the EGR ratio and temperature. Hot EGR was recirculated directly from the engine exhaust to the intake manifold. A heat exchanger was utilized to maintain the temperature of the cooled EGR at 25 °C.The supplied hydrogen increased NOx concentrations in the exhaust gas emissions and high EGR rates reduced the brake thermal efficiency. The reduction in NOx emissions depended on the added hydrogen and the EGR ratios when compared with pure diesel combustion. Adding hydrogen to significant amounts of recycled exhaust gas reduced the CO, PM, and unburned hydrocarbon (HC) emissions significantly. Results showed that using hydrogen and biodiesel increases engine noise, which is reduced by adding high levels of EGR.     

6BTA 5.9 G2-1 Cummins engine performance and emission tests using methyl ester mahua (Madhuca indica) oil/diesel blends

Neat mahua oil poses some problems when subjected to prolonged usage in CI engine. The transesterification of mahua oil can reduce these problems. The use of biodiesel fuel as substitute for conventional petroleum fuel in heavy-duty diesel engine is receiving an increasing amount of attention. This interest is based on the properties of bio-diesel including the fact that it is produced from a renewable resource, its biodegradability and potential to exhaust emissions. A Cummins 6BTA 5.9 G2- 1, 158 HP rated power, turbocharged, DI, water cooled diesel engine was run on diesel, methyl ester of mahua oil and its blends at constant speed of 1500 rpm under variable load conditions. The volumetric blending ratios of biodiesel with conventional diesel fuel were set at 0, 20, 40, 60, and 100. Engine performance (brake specific fuel consumption, brake specific energy consumption, thermal efficiency and exhaust gas temperature) and emissions (CO, HC and NOx) were measured to evaluate and compute the behavior of the diesel engine running on biodiesel. The results indicate that with the increase of biodiesel in the blends CO, HC reduces significantly, fuel consumption and NOx emission of biodiesel increases slightly compared with diesel. Brake specific energy consumption decreases and thermal efficiency of engine slightly increases when operating on 20% biodiesel than that operating on diesel.     

Biodiesel production from waste cooking oil using heterogeneous catalysts and its operational characteristics on variable compression ratio CI engine

In the present work, the optimum biodiesel conversion from waste cooking oil to biodiesel through transesterification method was investigated. The base catalyzed transesterification under different reactant proportions such as the molar ratio of alcohol to oil and mass ratio of catalyst to oil was studied for optimum production of biodiesel. The optimum condition for base catalyzed transesterification of waste cooking oil was determined to be 12:1 and 5 wt% of zinc doped calcium oxide. The fuel properties of the produced biodiesel such as the calorific value, flash point and density were examined and compared to conventional diesel. The properties of produced biodiesel and their blend for different ratios (B20, B40, B60, B80 and B100) were comparable with properties of diesel oil and ASTM biodiesel standards. Tests have been conducted on CI engine which runs at a constant speed of 1500 rpm, injection pressure of 200 bar, compression ratio 15:1 and 17.5, and varying engine load. The performance parameters include brake thermal efficiency, brake specific energy consumption and emissions parameters such as Carbon monoxide (CO), Hydrocarbon (HC), Oxides of Nitrogen (NOx) and smoke opacity varying with engine load (BP). Diesel engine's thermal performance and emission parameters such as CO, HC, and NOx on different biodiesel blends demonstrate that biodiesel produced from waste cooking oil using heterogeneous catalyst was suitable to be used as diesel oil blends and had lesser emissions as compared to conventional diesel.     

Effect of hydrogen on compression-ignition (CI) engine fueled with vegetable oil/biodiesel from various feedstocks: A review

Compression ignition (CI) engines used in the transportation sector operates on fossil diesel and is one of the biggest causes of air pollution. Numerous studies were carried out over last two decades to substitute the fossil diesel with biofuels so that the net carbon dioxide (CO₂) emission can be minimized. However, the engine performance with these fuel was sub-standard and there were many long-term issues. Therefore, many researchers inducted hydrogen along with the biofuels. The present study gives an outlook on the effect of hydrogen addition with biodiesel/vegetable oil from various sources in CI engine. Engine parameters (brake thermal efficiency, brake specific fuel consumption), combustion parameters (in-cylinder pressure and heat release rate) and emission parameters (unburned hydrocarbon (HC), carbon monoxide (CO), oxides of nitrogen (NOx) and smoke emissions) were evaluated in detail. The results show that hydrogen induction in general improves the engine performance as compared to biodiesel/vegetable oil but it is similar/lower than diesel. Except NOx emissions all other emissions showed a decreasing trend with hydrogen addition. To counter this effect numerous after-treatment systems like selective catalytic reduction (SCR), exhaust gas recirculation (EGR), selective non-catalytic reduction system (SNCR) and non-selective catalytic reduction system (NSCR) were proposed by researchers which were also studied in this review.     

The effects of turbocharger on the performance and exhaust emissions of a diesel engine fuelled with biodiesel

This paper investigates the effects of turbocharger on the performance of a diesel engine using diesel fuel and biodiesel in terms of brake power, torque, brake specific consumption and thermal efficiency, as well as CO and NO_x emissions. For this aim, a naturally aspirated four-stroke direct injection diesel engine was tested with diesel fuel and neat biodiesel, which is rapeseed oil methyl ester, at full load conditions at the speeds between 1200 and 2400 rpm with intervals of 200 rpm. Then, a turbocharger system was installed on the engine and the tests were repeated for both fuel cases. The evaluation of experimental data showed that the brake thermal efficiency of biodiesel was slightly higher than that of diesel fuel in both naturally aspirated and turbocharged conditions, while biodiesel yielded slightly lower brake power and torque along with higher fuel consumption values. It was also observed that emissions of CO in the operations with biodiesel were lower than those in the operations with diesel fuel, whereas NO_x emission in biodiesel operation was higher. This study reveals that the use of biodiesel improves the performance parameters and decreases CO emissions of the turbocharged engine compared to diesel fuel.     

A study on the performance and emission of a diesel engine fueled with Jatropha biodiesel oil and its blends

Biodiesel either in neat form or as a mixture with diesel fuel is widely investigated to solve the twin problem of depletion of fossil fuels and environmental degradation. The main objective of the present study is to compare performance, emission and combustion characteristics of biodiesel derived from non edible Jatropha oil in a dual fuel diesel engine with base line results of diesel fuel. The performance parameters evaluated were: brake thermal efficiency, brake specific fuel consumption, power output. As a part of combustion study, in-cylinder pressure, rate of pressure rise and heat release rates were evaluated. The emission parameters such as carbon monoxide, carbon dioxide, un-burnt hydrocarbon, oxides of nitrogen and smoke opacity with the different fuels were also measured and compared with base line results. The different properties of Jatropha oil after transestrification were within acceptable limits of standards as set by many countries. The brake thermal efficiency of Jatropha methyl ester and its blends with diesel were lower than diesel and brake specific energy consumption was found to be higher. However, HC, CO and CO₂ and smoke were found to be lower with Jatropha biodiesel fuel. NO_x emissions on Jatropha biodiesel and its blend were higher than Diesel. The results from the experiments suggest that biodiesel derived from non edible oil like Jatropha could be a good substitute to diesel fuel in diesel engine in the near future as far as decentralized energy production is concerned. In view of comparable engine performance and reduction in most of the engine emissions, it can be concluded and biodiesel derived from Jatropha and its blends could be used in a conventional diesel engine without any modification.     

生物柴油对直喷式柴油机燃烧和排放的影响

列举了生物柴油的基本物化特性。介绍了生物柴油对直喷式柴油机燃烧和排放的影响。相比普通柴油,燃用生物柴油可以减少CO、CO_2、SO_2、HC、微粒以及碳烟的排放且不会影响柴油机工作性能。采用EGR、乳化油、多次喷射及微粒捕捉器等措施可以进一步降低使用生物柴油的微粒和NOx排放。生物柴油作为一种可再生的替代能源,以其良好的环境效应受到越来越多的关注。     

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。     

Engine combustion and emission fuelled with natural gas: A review

Natural gas (NG) is one of the most important and successful alternative fuels for vehicles. Engine combustion and emission fuelled with natural gas have been reviewed by NG/gasoline bi-fuel engine, pure NG engine, NG/diesel dual fuel engine and HCNG engine. Compared to using gasoline, bi-fuel engine using NG exhibits higher thermal efficiency; produces lower HC, CO and PM emissions and higher NOx emission. The bi-fuel mode can not fully exert the advantages of NG. Optimization of structure design for engine chamber, injection parameters including injection timing, injection pressure and multi injection, and lean burn provides a technological route to achieve high efficiency, low emissions and balance between HC and NOx. Compared to diesel, NG/diesel dual fuel engine exhibits longer ignition delay; has lower thermal efficiency at low and partial loads and higher at medium and high loads; emits higher HC and CO emissions and lower PM and NOx emissions. The addition of hydrogen can further improve the thermal efficiency and decrease the HC, CO and PM emissions of NG engine, while significantly increase the NOx emission. In each mode, methane is the major composition of THC emission and it has great warming potential. Methane emission can be decreased by hydrogen addition and after-treatment technology.