柴油添加剂降低燃油消耗率及排放的试验研究

在Y4100Q自然吸气柴油机试验台架上使用0#柴油及加入6种不同添加剂的0#柴油,对两者进行比较。给出了柴油机排放物CO,HC,NOX,PM及燃油消耗率的测试结果。分析了排放物的生成机理及不同成分或不同量的添加剂对柴油机排放和燃油消耗率的影响。     

柴油硫含量对发动机颗粒物排放影响的研究

硫含量是柴油的主要特性之一,它对柴油机排放具有重要的影响.本文选择两台涡轮增压柴油机,一台柴油机在发动机试验台上进行ECE R-49试验,另一台安装在轿车上的高速、4缸、直喷共轨、涡轮增压、排量为2L的柴油机在汽车底盘测功器上进行NEDC试验,研究了硫含量对柴油机颗粒物排放的影响.研究结果表明:柴油中的硫含量对柴油机颗粒排放有很大影响,减少柴油硫含量能直接降低柴油机的颗粒物排放.     

柴油硫含量对发动机排放性能影响的研究

在一台直喷式涡轮增压柴油机上分别燃用4种不同硫含量的柴油,研究了燃油硫含量对柴油机排放性能的影响.研究结果表明,燃油硫含量对柴油机的烟度有直接影响,随着燃油硫含量的降低,柴油机的烟度明显下降,低负荷下燃油硫含量对柴油机的烟度影响较大,NOx排放随燃油硫含量的降低变化很小,而CO和HC排放则降幅明显,SO2排放随柴油机负荷的增加显著上升,随燃油含硫量的降低而显著下降.     

EGR冷却温度对重型柴油机性能及排放的影响

以一台配有废气再循环(exhaust gas recirculation,EGR)冷却系统和可变几何截面涡轮增压器的高压共轨重型柴油机作为研究对象,进行了EGR冷却温度对柴油机性能及排放影响的台架试验研究。结果表明:随着EGR冷却温度降低,柴油机燃油消耗率、烟度和NOx排放均持续降低。而EGR冷却温度每降低1℃,柴油机燃油消耗率、烟度和NOx排放在不同转速、负荷下降幅差异明显。燃油消耗率在中等转速、低负荷工况降幅最大,NOx排放和烟度在高转速、低负荷工况下降幅最大;在考虑到EGR冷却系统消耗的能量后,可以通过计算得到理论燃油消耗率。在兼顾燃油消耗率和排放性的原则下得到了各工况下EGR相对最优冷却温度,而所得到的相对最优EGR冷却温度正是各个试验工况下理论燃油消耗率最低的温度。     

冷却水温度变化对柴油机油耗率与排放的影响

在冷却水恒温控制试验台上对YC6A220C柴油机进行测试,研究柴油机在不同工况下运行时冷却水温度对燃油消耗率与排放性能的影响。     

气道喷水和废气再循环对重型柴油机性能和排放影响的优化匹配试验研究

在一台高压共轨重型柴油机上开展了气道喷水结合高压废气再循环(EGR)的试验研究。基于世界统一稳态测试循环(WHSC)各工况点探索引入高压EGR和气道喷水技术对柴油机排放和燃油经济性的影响;在此基础上对各工况的燃烧相位进行优化,得到WHSC各工况点下基于喷水和EGR的优化策略。结果表明:综合考虑排放和燃油经济性,低负荷工况宜单独引入高压EGR,并通过提前喷油时刻(start injection timing,SOI)优化燃烧相位;中高负荷工况宜少量喷水并引入适当EGR,满负荷则应单独采取气道喷水策略。WHSC加权结果表明,在保持较低的HC、CO和碳烟排放前提下,优化后的加权NOx比排放降低7.71g/(kW·h),降幅约45.2%,有效燃油消耗率降低约1.20g/(kW·h)。     

丙酮丁醇乙醇/汽油混合燃料对高速发动机性能影响的试验研究

以发动机4000 r/min、节气门开度35％ 为试验工况,对纯汽油及不同掺混体积分数丙酮丁醇乙醇(acetone-butanol-ethanol,ABE)与汽油混合物开展了不同点火提前角和喷油量的试验研究.分析了不同ABE混合比、点火提前角和过量空气系数对发动机性能的影响,并对每种燃料发动机最大功率工况的性能参数进行...     

柴油中溶入甲烷对发动机燃烧排放特性的影响

设计了几种不同甲烷含量的甲烷／柴油混合燃料,在实用柴油机上对它们的燃烧和排放特性进行了试验研究。研究结果表明,根据柴油中甲烷含量的不同,溶气对比油耗和热效率有正反两方面的影响;溶有甲烷的柴油与纯柴油相比有较长的着火滞燃期和较低的最大放热率;柴油中甲烷的溶解量越大,滞燃期越长,最高放热率越低;与纯柴油相比,溶有甲烷柴油的NOx排放降低,HC排放增加;在较高的甲烷溶解度时,NOx和烟度排放能够同时降低。     

发动机燃用不同硫含量柴油的排放特性研究

研究了1台轻型柴油机燃用5种不同典型硫含量柴油时的排放特性.结果表明,随燃油硫含量的降低,柴油机颗粒质量和烟度排放均明显下降,低负荷下燃油硫含量对柴油机烟度值的影响较大,表明燃油硫含量对柴油机排气颗粒和烟度有直接影响.柴油机氮氧化物排放随燃油硫含量降低的变化很小,而一氧化碳和未燃碳氢排放则降幅明显.二氧化硫排放随柴油机负荷增加显著上升,随燃油硫含量降低而显著下降,表明了燃油硫含量与柴油机二氧化硫排放之间的高度相关性.     

Shape memory effect heat engine performance

The performance of a shape memory effect heat engine has been evaluated taking into account the heat transfer to the working element, hysteresis effects, elasticity and heat losses. It is shown that there exists an optimum stress required for maximum power output. The maximum power output is found to increase with increasing cycle temperature difference, increasing cycle strain, increasing working element heat transfer coefficient and decreasing size of the working element. Calculations for Nitinol and CuZnAl working elements, operating on a 60°C temperature difference and 2% cycle strain, indicate maximum power densities of approximately 1 W/g and conversion efficiencies of approximately 1%.     

The effect of biodiesel oxidation on engine performance and emissions

Biodiesel is an alternative fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Previous research has shown that biodiesel-fueled engines produce less carbon monoxide, unburned hydrocarbons, and particulate emissions compared to diesel fuel. One drawback of biodiesel is that it is more prone to oxidation than petroleum-based diesel fuel. In its advanced stages, this oxidation can cause the fuel to become acidic and to form insoluble gums and sediments that can plug fuel filters. The objective of this study was to evaluate the impact of oxidized biodiesel on engine performance and emissions. A John Deere 4276T turbocharged DI diesel engine was fueled with oxidized and unoxidized biodiesel and the performance and emissions were compared with No. 2 diesel fuel. The neat biodiesels, 20% blends, and the base fuel (No. 2 diesel) were tested at two different loads (100 and 20%) and three injection timings (3° advanced, standard; 3° retarded). The tests were performed at steady-state conditions at a single engine speed of 1400 rpm. The engine performance of the neat biodiesels and their blends was similar to that of No. 2 diesel fuel with the same thermal efficiency, but higher fuel consumption. Compared with unoxidized biodiesel, oxidized neat biodiesel produced 15 and 16% lower exhaust carbon monoxide and hydrocarbons, respectively. No statistically significant difference was found between the oxides of nitrogen and smoke emissions from oxidized and unoxidized biodiesel.     

Effect of heat recovery on the performance of a shape-memory effect heat engine

The performance of a shape-memory effect heat engine employing heat recovery has been modelled taking into account heat transfer to the working element and non-ideal material behaviour. Calculations of the energy flux to and from the working element show that a substantial fraction of the sensible heating requirements can be recovered by heat transfer between the heating and cooling stages. The increase in efficiency due to heat recovery and the resulting power output are shown to be a function of stress and rate of temperature change of the heat-transfer fluid. Working element-fluid heat transfer and hysteresis behaviour of the shape-memory working element are found to limit the efficiency improvement associated with heat recovery.     

The investigation of the effect of thermal barrier coating on the performance of Stirling engine

The shuttle heat transfer is one of the reasons reducing the performance of Stirling engines. This study is concerned with the reduction in shuttle heat transfer by coating the displacer. The displacer of a gamma type Stirling engine was coated with a layer of yttria‐stabilized zirconia (YSZ), and the effect of the coating on the engine performance was evaluated by comparing speed‐power and speed‐torque characteristics of the engine with coated and uncoated displacers. Characteristics were obtained for 700, 800 and 900°C heater temperatures. At each stage of the heater temperature, the charge pressure ranged from 1 to 3.5 bars with 0.5 bar increments. At 900°C heater temperature and 3 bars charge pressure, the shaft power before coating was 34.9 W, after coating the power increased to 43.8 W, which corresponds to a 25% increment. The temperature applied to the engine did not cause any damage on the coating layer. Copyright © 2008 John Wiley & Sons, Ltd.     

Experimental study of the effect of fuel types on the performance of spark ignition engine

Different fuels are being used daily in the city of Kirkuk, Iraq for operating vehicles with spark-ignition internal combustion engines. Aiming to address the effects of these fuels on both engines and the environment, this work conducts an experimental study where a single-cylinder, four-stroke small spark ignition engine is employed. Three types of benzene with different octane ratings (low with an additive [85.8%], medium [89.2%], and high [95.6%]) are utilized in the study as they are the most consumed fuel in the area of the study. Moreover, the low-octane fuel will be addressed with a commercial additive. In addition to engine performance, the exhaust gases and sound levels are analyzed as well. Through the outcomes, it is observed that the fuel with higher octane numbers relatively produces better engine performance and pollution. At normal engine speed, the fuel with a medium octane rating, however, has close engine performance results but with worse pollution effects. On the other hand, the engine fails to start with low-octane fuel without the additive. The additive improves the engine performance with the low octane fuel and surprisingly produces fewer pollution gases than the fuel with medium octane number. However, the engine still behaves worse than with the other fuels at normal engine speed.     

Evaluation of water injection effect on compressor and engine performance and operability

Gas turbine performance enhancement technologies such as inlet fogging, combustor water/steam injection and overspray are being employed by users in recent years without fully evaluating their effect on gas turbine performance and operability. The water injection techniques can significantly affect the engine operating point thus a careful analysis should precede the application of performance enhancement devices, especially when the devices are retrofitted to old engines or engines operating at extreme conditions. The present paper examines the most widespread techniques that implement water injection by using in-house models that can reproduce the effects of water injection on the gas turbine and compressor off-design operation. The results are analyzed with respect to both performance augmentation and engine operability in order to give further insight on gas turbine operation with water injection. The behaviour of the gas turbine is interpreted while the risks on engine integrity due to water injection are identified.     

The effect of clove oil and diesel fuel blends on the engine performance and exhaust emissions of a compression-ignition engine

Diesel engines provide the major power source for transportation in the world and contribute to the prosperity of the worldwide economy. However, recent concerns over the environment, increasing fuel prices and the scarcity of fuel supplies have promoted considerable interest in searching for alternatives to petroleum based fuels. Based on this background, the main purpose of this investigation is to evaluate clove stem oil (CSO) as an alternative fuel for diesel engines. To this end, an experimental investigation was performed on a four-stroke, four-cylinder water-cooled direct injection diesel engine to study the performance and emissions of an engine operated using the CSO–diesel blended fuels. The effects of the CSO–diesel blended fuels on the engine brake thermal efficiency, brake specific fuel consumption (BSFC), specific energy consumption (SEC), exhaust gas temperatures and exhaust emissions were investigated. The experimental results reveal that the engine brake thermal efficiency and BSFC of the CSO–diesel blended fuels were higher than the pure diesel fuel while at the same time they exhibited a lower SEC than the latter over the entire engine load range. The variations in exhaust gas temperatures between the tested fuels were significant only at medium speed operating conditions. Furthermore, the HC emissions were lower for the CSO–diesel blended fuels than the pure diesel fuel whereas the NO_x emissions were increased remarkably when the engine was fuelled with the 50% CSO–diesel blended fuel.     

The effect of displacer material on the performance of a low temperature differential Stirling engine

In this study, a gamma‐type low temperature differential Stirling engine was designed and manufactured. The displacer and piston of the engine were concentrically situated to each other. The engine was tested by using a liquefied petroleum gas burner at laboratory conditions. The working fluid was ambient air at atmospheric pressure. Test procedure intended to investigate the speed‐torque and speed‐power characteristics of the engine depending on the hot‐end temperature. Two different displacers made of aluminum alloy and medium density fiberboard were used. The maximum torque and power obtained were 0.166 Nm at 125 rpm speed and 3.06 W at 215 rpm speed, respectively, at 160 °C hot‐end temperature with medium density fiberboard displacer. Copyright © 2011 John Wiley & Sons, Ltd.     

不可逆变温热源斯特林热机的?生态学性能研究

基于?的生态学目标函数,使用一种新的指标——?生态指标对不可逆变温热源斯特林热机进行了分析。在热机高低温热源的热容均为有限的前提下,考虑斯特林热机的热阻、回热损失、内不可逆性以及热漏对其影响。研究了回热器的回热效率和高低温热源的热容的比值等参数对斯特林热机的功率、效率和?生态学指标的影响,并将结果与另一种生态目标函数的结果进行了比较,得到最佳功率输出功率和热效率。     

Examination of the effect of combustion chamber geometry and mixing ratio on engine performance and emissions in a hydrogen-diesel dual-fuel compression-ignition engine

The fact that fossil fuels, which supply a large amount of the energy need, are limited in the world and can be only found in certain regions, have led humankind to seek alternatives. In addition, the use of fossil fuels generates wastes detrimental to humans and nature, which has led this search to alternative, clean and renewable energy sources. The use of hydrogen, which is a clean energy source, in internal combustion engines is very important in terms of reducing emission values as well as providing an alternative to petroleum-derived fuels. This study presents a literature review on the effect of the hydrogen ratio and combustion chamber geometry on the engine performance and emissions in a compression-ignition engine operating in the hydrogen diesel bi-fuel mode. As a result of the study, it was concluded that the hydrogen energy ratio should be between 5 and 20% and the combustion chamber should be designed by considering the combustion characteristics. The main purpose of the study is to highlight the functionality of the use of hydrogen in dual fuel mode in compression ignition engines and to be a resource for researchers who will work on this subject.