乙醇与柴油混合燃料燃烧特性及排放特性的试验研究

在一台YC4112ZLQ增压柴油机上进行了不加任何助溶剂和着火改进剂的情况下,无水乙醇与柴油混合对柴油机燃烧过程影响的研究。试验结果表明,随着混合燃料中乙醇比例的提高,滞燃期延长,放热峰值增大,缸内最大爆发压力和最大压力升高率升高。与柴油相比,E10和E20有效热效率与原机相当,E30在高速大负荷工况热效率降低,NOx和碳烟排放明显降低;但HC和CO排放随着混合燃料中乙醇比例的增大,发动机转速为1500 r／min时,HC排放和CO排放均降低,发动机转速为2300 r／min时,HC排放和CO排放均有所升高。     

燃烧乙醇-柴油时发动机的性能与排放特性研究

在一台双缸直喷式柴油机上,对燃烧乙醇-柴油时发动机的燃油经济性和排放性进行试验。试验结果表明：与纯柴油相比,乙醇-柴油的当量燃油消耗率和CO排放量在较大负荷工况下有所减小,NOx和碳烟排放在各种工况下都显著降低,但HC的排放量增加;适当减小发动机的供油提前角,对提高燃油经济性和排放性有利。     

供油提前角对含水乙醇-生物柴油发动机性能的影响

在对含水乙醇和生物柴油互溶性研究的基础上,进行了不同供油提前角下B90A10混合燃料柴油机经济性与排放特性的对比试验研究。试验结果表明:生物柴油和含水乙醇具有良好的互溶性;柴油机原机供油提前角为18°CA BTDC时,B90A10有效燃油消耗率较低,供油提前角增大或减小都使燃油经济性不同程度地恶化;低负荷工况下,16°CA,18°CA,20°CA BTDC供油提前角时的CO排放水平相当;中、高负荷工况下,随着供油提前角的减小,CO排放量依次增大。随着供油提前角的增大,碳烟排放降低,而NOx排放上升,呈现折中(Trade-off)的关系;HC排放对供油提前角的变化不敏感,总体排放量接近。对B90A10混合燃料的台架试验结果分析表明,多组分B90A10混合燃料是一种较为理想的柴油机代用燃料。     

供油提前角对柴油/水煤浆混合燃料燃烧排放性能的影响

通过柴油机台架试验,分析了供油提前角变化对柴油/水煤浆混合燃料燃烧排放的影响.试验结果表明:当供油提前角调定为18 ℃A时,柴油/水煤浆混合燃料的有效燃油消耗率降低,热效率升高,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/水煤浆混合燃料的排放有较大影响,逐步增大供油提前角(由17到18 ℃A,再到19 ℃A),混合燃烧的烟度排放降低,Nox的排放先降低再升高,CO的排放先升高再降低,HC排放升高.     

二甲醚发动机碳氢排放特性试验研究

以226B压燃式二甲醚发动机为研究对象,通过对比试验分析了二甲醚喷油器启喷压力、喷孔直径、喷油提前角和发动机功率对HC排放性的影响。试验结果表明:在外特性的整个转速范围内,随发动机转速的增加HC排放呈先增加后减小的趋势,随喷油器启喷压力的升高HC排放呈降低趋势;外特性在1 000~1 300r/min低速情况下,喷孔直径0.38mm的喷油器HC排放低,转速在1 500~2 300r/min范围内,喷孔直径0.36mm的喷油器HC排放较低;静态供油提前角由曲轴转角13°推迟到8°,外特性HC排放呈先降低后升高的趋势;随着二甲醚发动机负荷率的升高,其HC排放呈降低趋势。     

增压稀燃天然气发动机排放特性

为了研究增压稀燃天然气发动机的排放特性,对发动机进行了空燃比和点火提前角调整试验、十三工况排放等试验,并在增加氧化型催化转化器后进行了相关试验,对试验结果进行研究分析,获得了天然气发动机的排放规律.结果表明:NMHC排放随空燃比增大先减少后增加,NOx排放随空燃比增大先增加后减少,在空燃比19～21左右达到最大值.NMHC比排放随转速升高略有降低,NOx排放随转速升高先减小后增加,发动机最低NOx排放点所对应的发动机转速为1600～1800 r/min.定MAP下,NMHC排放随点火提前角增大先降低后增加,NOx排放随点火提前角增大而增大.加Ⅰ型氧化催化器后发动机NOx、CH4、CO、NMHC排放值分别减少了15%、97%、78%、60%.试验结果表明,增压稀燃和氧化型催化转化器相结合是天然气发动机一种有效方案.     

柴油甲醇组合燃烧对机车柴油机排放性能的影响

对一台应用于机车的中速大型柴油机,按照柴油/甲醇组合燃烧(DMCC)的要求,进行了相应的改造,以探究DMCC燃烧模式对其排放性能的影响。结果表明:在800 r/min@9 600 N·m工况下,掺烧甲醇后,NO_x比排放大幅降低,但过分提高甲醇替代率,则NO_x比排放会有所升高;CO₂比排放、燃料费用随甲醇替代率的升高而降低;当量油耗则先随甲醇的替代率提高而升高,随后降低;HC比排放随甲醇替代率提高有所升高。相比于原机,在800 r/min、9 600 N·m、-4° ATDC、35.9%替代率工况, NO_x比排放仅为3.15 g/(kW·h),最大降幅达到56.5%;DMCC模式,640 r/min@6 850 N·m工况下,随着供油提前角的推迟,NO_x、HC比排放降低,排气温度逐渐升高;中等替代率下最低油耗对应的供油提前角推迟,高替代率下供油提前角提前。     

军用装备发动机最佳供油提前角的试验研究

讨论了供油提前角对发动机动力性、经济性和排放性能的重要性,利用外特性试验、负荷特性试验和转速稳定性试验,考察了供油提前角对发动机工况的影响。研究结果表明,对于12150ZLD发动机来讲,供油提前角对动力性影响较大,功率和扭矩的最大差距分别为7.6%和7.5%,油耗率最大相差6.6%。其中供油提前角为26°时,发动机运转正常,功率、扭矩最高,油耗率最低,气缸的最大爆发压力符合要求,为该型发动机的最佳供油提前角。为保证装备长期运行或更换燃料后仍发挥最优性能,应及时调整供油提前角。     

柴油/CNG双燃料发动机排放性能的试验研究

在设计开发的CA6113BN-01柴油/CNG双燃料发动机的基础上，通过改变燃烧系统参数，柴油供油系统参数和在天然气供气系统参数等，研究了这些参数变化时对柴油/CNG双燃料发动机排放特性的影响。试验结果表明：柴油/CNG双燃料发动机的燃烧室形状对双燃料发动机性能，排放的影响较小。NOx、HC排放量随提前角的变化趋势和柴油机相似，提前角增大，NOx排放量增加，HC排放量也增加，提前角对CO排放影响较小。喷油器的开启压力提高可以有效地改善双燃料发动机的排放。     

发动机有害气体排放的RSM模型

在发动机试验台上,对测量系统进行分析,在此基础上,以发动机转速v和点火提前角θ为因子,以发动机有害气体HC,CO和NO的排放量为试验指标进行了试验研究,建立单因子的二次回归模型,依据响应面理论(RSM),建立了排放指标HC,CO和NO相对于因子v和θ的二次响应面模型,并进行了分析,主要结论:HC在发动机转速为4 000 r/min,点火提前角为4°时的排放量最小;CO在发动机转速为4 000 r/min,点火提前角为16°时的排放量最小;NO在发动机转速为1 000 r/min,点火提前角为4°时的排放量最小。     

非道路涡轮增压柴油机高原适应性研究

为改善非道路柴油机高海拔条件下功率下降、经济性及排放性能恶化、高速增压器超速等问题,利用柴油机高原环境模拟台架试验结合一维仿真研究了0～4 000m海拔环境下增压器运行特性、柴油机综合性能参数等随海拔高度的变化规律及影响机理。针对柴油机的变海拔性能恢复目标,通过对增压系统进行参数计算和选配,提出一种带有废气旁通阀的两级涡轮增压匹配方案。研究结果表明:变海拔条件下,非道路柴油机各性能参数呈现非线性变化,在转速800～2 800r/min全负荷工况下,柴油机动力性、经济性变化梯度呈现出先减小后增大的"浴盆形"趋势。在0～2 000m海拔环境下,柴油机转矩降幅达4.3%,有效燃油消耗率降幅达6%。随着海拔升高,中冷前温度与涡前温度逐渐升高,增压压力与涡前压力逐渐降低,CO、全碳氢和NO_x排放升高。匹配两级增压系统后,对比原机4 000m海拔运行工况,柴油机功率平均升高14.9%,有效燃油消耗率平均降低11.8%,实现了非道路柴油机的高海拔性能恢复目标。     

Reducing the idle speed of an SI CNG engine fueled by HCNG with high hydrogen ratio

This paper presents an experimental study aimed at idle characteristics of a CNG engine fueled by HCNG with 55% hydrogen blend. The idle speed was reduced from original 800 r/min to 750 r/min and 700 r/min, and the characteristics of combustion & emissions at reduced idle speed were investigated. It is found that, for the HCNG engine, only reducing idle speed cannot reduce fuel consumption at conditions of fixed λ. In order to reduce fuel consumption and keep the COV at rather low levels, the excess air ratio must be increased properly while reducing the engine idle speed. Due to the large valve overlap (30°) of this inlet inject HCNG engine, CH₄ emissions are mainly caused by scavenging, which account for the vast majority of THC emissions. The emissions of CO, THC and NOx are reduced with the decrease of ignition advance angle at a fixed λ.     

A modified diesel engine for natural gas operation: Performance and emission tests

A diesel engine was modified for natural gas operation to optimize performance using gaseous fuel. A variation of combustion ratios (CR) including 9.0:1, 9.5:1, 10.0:1 and 10.5:1 was utilized to evaluate engine performance and emissions from the same engine over the engine speeds between 1000 and 4000 rpm. Tested engine performance parameters include brake torque, brake power, specific fuel consumption (SFC) and brake thermal efficiency. Emissions tests recorded total hydrocarbon (THC), nitrogen oxides (NO_x) and carbon monoxide (CO). The results showed that a CR of 9.5:1 had the highest thermal efficiency and the lowest SFC while a CR of 10:1 showed a high torque at low speed. THC emissions were directly proportional to the CR. NO_x emissions increased with increasing CR and then declined after a CR of 10:1.     

电喷汽油机燃用乙醇-汽油燃料的排放性能研究

研究了不同掺混比的乙醇 -汽油燃料在多点电喷汽油机上应用时的排放性能。研究结果表明 :在汽油机参数未做任何调整的情况下 ,在试验的掺混比范围内 ,随着乙醇 -汽油混合燃料中乙醇含量的增加 ,THC排放改善了 30 %,CO排放在大负荷时有所改善 ,NOx 排放在中、小负荷时改善较明显。排放特性的变化不仅与乙醇含量有关 ,而且与电喷发动机的空燃比控制策略有关。以质量计的燃油消耗率有所增加 ,但以燃料热值计的比能耗降低。     

Effects of turpentine and gasoline-like fuel obtained from waste lubrication oil on engine performance and exhaust emission

In this study, an experimental investigation was carried out to determine the effects of gasoline-like fuel (GLF), and its blends with turpentine with ratios of 10%, 20%, and 30% on the performance and emission characteristics of a gasoline engine. The GLF was obtained from waste lubrication engine oil by the method of pyrolitic distillation. Characteristics of the pure GLF and its blends were tested. A series of engine performance and emission tests were conducted using the fuel samples in the test engine. Performance parameters for each test were calculated utilizing measurement values of force exerted on the crank shaft, rate of air and fuel mass flow to the engine and engine speed. Effects of the fuels on the performance parameters, exhaust gas temperature, and emissions of NOx, CO, CO₂, and HC were discussed. The results indicated that torque, brake mean effective pressure and thermal efficiency increased but brake specific fuel consumption decreased with increasing amount of turpentine in the GLF sample. The main effect of 10%, 20% and 30% turpentine additions to GLF on pollutant formation was that the NOx ratio increased, whereas that of CO decreased.     

Experimental and numerical investigation of effects of CNG and gasoline fuels on engine performance and emissions in a dual sequential spark ignition engine

Compared to widening usage of CNG in commercial gasoline engines, insufficient but increasing number of studies have appeared in open literature during last decades while engine characteristics need to be quantified in exact numbers for each specific fuel converted engine. In this study, a dual sequential spark ignition engine (Honda L13A4 i-DSI) is tested separately either with gasoline or CNG at wide open throttle. This specific engine has unique features of dual sequential ignition with variable timing, asymmetrical combustion chamber, and diagonally positioned dual spark-plug. Thus, the engine led some important engine technologies of VTEC and VVT. Tests are performed by varying the engine speed from 1500 rpm to 4000 rpm with an increment of 500 rpm. The engine’s maximum torque speed of 2800 rpm is also tested. For gasoline and CNG fuels, engine performance (brake torque, brake power, brake specific fuel consumption, brake mean effective pressure), emissions (O₂, CO₂, CO, HC, NO_x, and lambda), and the exhaust gas temperature are evaluated. In addition, numerical engine analyses are performed by constructing a 1-D model for the entire test rig and the engine by using Ricardo-Wave software. In the 1-D engine model, same test parameters are analyzed, and same test outputs are calculated. Thus, the test and the 1-D engine model are employed to quantify the effects of gasoline and CNG fuels on the engine performance and emissions for a unique engine. In general, all test and model results show similar and close trends. Results for the tested commercial engine show that CNG operation decreases the brake torque (12.7%), the brake power (12.4%), the brake mean effective pressure (12.8%), the brake specific fuel consumption (16.5%), the CO₂ emission (12.1%), the CO emission (89.7%). The HC emission for CNG is much lower than gasoline. The O₂ emission for CNG is approximately 55.4% higher than gasoline. The NO_x emission for CNG at high speeds is higher than gasoline. The variation percentages are the averages of the considered speed range from 1500 rpm to 4000 rpm.     

Physico-chemical properties of ethanol–diesel blend fuel and its effect on performance and emissions of diesel engines

The effects of different ethanol–diesel blended fuels on the performance and emissions of diesel engines have been evaluated experimentally and compared in this paper. The purpose of this project is to find the optimum percentage of ethanol that gives simultaneously better performance and lower emissions. The experiments were conducted on a water-cooled single-cylinder Direct Injection (DI) diesel engine using 0% (neat diesel fuel), 5% (E5–D), 10% (E10–D), 15% (E15–D), and 20% (E20–D) ethanol–diesel blended fuels. With the same rated power for different blended fuels and pure diesel fuel, the engine performance parameters (including power, torque, fuel consumption, and exhaust temperature) and exhaust emissions [Bosch smoke number, CO, NO_x, total hydrocarbon (THC)] were measured. The results indicate that: the brake specific fuel consumption and brake thermal efficiency increased with an increase of ethanol contents in the blended fuel at overall operating conditions; smoke emissions decreased with ethanol–diesel blended fuel, especially with E10–D and E15–D. CO and NO_x emissions reduced for ethanol–diesel blends, but THC increased significantly when compared to neat diesel fuel.     

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.     

生物柴油/甲醇混合燃料对柴油机性能与排放的影响研究

在一台4缸直喷式柴油机上研究了超低硫柴油、生物柴油及后者与甲醇的混合燃料对发动机性能、气体及微粒排放的影响。生物柴油由餐饮废油制取,除单独使用外和甲醇按体积比90：10和80：20混合后使用。在最大扭矩转速1800 r.m in-1时,在5个不同负荷下,比较了不同燃料热效率及CO、HC、NOx以及微粒质量浓度,微粒的总数量及平均几何粒径。结果表明,和超低硫柴油相比,生物柴油及其和甲醇的混合燃料的热效率增加,NOx和微粒质量、数量浓度的排放降低,但HC、CO和NO2排放升高;同时,随着甲醇混合比例的增加,HC、CO和NO2的排放成比例增加,微粒的质量浓度及数量浓度进一步降低,热效率及NOx几乎保持不变。     

Syngas (H2/CO) in a spark-ignition direct-injection engine. Part 1: Combustion,performance and emissions comparison with CNG

The combustion, performance, and emissions of syngas (H₂/CO) in a four-stroke, direct-injection, spark-ignition engine were experimentally investigated. The engine was operated at various speeds, ranging from 1500 to 2400 rev/min, with the throttle being held in the wide-open position. The start of fuel injection was fixed at 180° before the top dead center, and the ignition advance was set at the maximal brake torque. The air/fuel ratio was varied from the technically possible lowest excess air ratio (λ) to lean operation limits. The results indicated that a wider air/fuel operating ratio is possible with syngas with a very low coefficient of variation. The syngas produced a higher in-cylinder peak pressure and heat-release rate peak and faster combustion than for CNG. However, CNG produced a higher brake thermal efficiency (BTE) and lower brake specific fuel consumption (BSFC). The BTE and BSFC of the syngas were on par to those of CNG at higher speeds. For the syngas, the total hydrocarbon emission was negligible at all load conditions, and the carbon monoxide emission was negligible at higher loads and increased under lower load conditions. However, the emission of nitrogen oxides was higher at higher loads with syngas.