PODE掺混比对电控共轨柴油机排放特性的影响

为了降低柴油机排放、提高热效率,将体积分数为10%、20%、30%和70%的聚甲氧基二甲醚(PODE)掺混于柴油中制得PODE/柴油混合燃料,标记为P10、P20、P30和P70,在一台四缸增压中冷电控共轨柴油机上开展了PODE掺混比对混合燃料燃油经济性与排放特性的试验,并采用热重分析仪研究了混合燃料的蒸发性能。结果表明:随PODE掺混比增加混合燃料的初始失重温度、终止失重温度和峰值失重温度均向低温区域偏移,峰值失重率增大;随PODE掺混比增加,柴油机的排气温度降低,有效热效率显著提升,混合燃料的HC、CO和烟度排放逐渐降低,而NOx排放有所增加;在ESC试验循环下P30的HC、CO和PM排放量较柴油分别降低了25%、16%和51%,均低于国V排放限值,且CO2排放量也明显减小。     

柴油机排气控制的研究进展

伴随着柴油机排放标准的日益严格,柴油机排气控制愈来愈受到重视。对降低柴油机微粒和NOx排放的发动机改造、燃料改进和排气后处理技术进行了综述,并指出了今后的努力方向。     

ArcGIS Engine支持下的排污口管理与水质预测信息系统的实现

从区域水环境管理的要求出发，对利用ArcGIS Engine开发的排污口管理与水质预测信息系统的开发过程进行介绍。简要介绍了该系统的目标、组成和主要功能，并从数据库建立、数据管理子系统、排污口管理子系统、水质预测子系统功能实现等方面对系统实现做了较为详细的阐述。     

吸入柴油机排出物对小鼠骨髓细胞微核出现率的影响

小鼠吸入过滤或未过滤的柴油机排出物，染毒８ｈ／ｄ，分别染毒２、５、８ｄ后，发现小鼠骨髓细胞微核率明显升高。吸入过滤后排出物的小鼠骨髓细胞微核出现率低于未过滤组。柴油机排出物对小鼠染色体有一定的损伤作用，过滤后的柴油机排出颗粒物中，致染色体损伤的物质减少，不同吸入时间（２、５、８ｄ）对小鼬骨髓细胞微核出现率，没有显著差异。     

重型车辆柴油机起动工况燃油喷射实验研究

目的研究重型车辆柴油机机械泵起动工况的喷油规律。方法基于Bosch长管法搭建某重型车辆柴油机机械泵起动过程燃油喷射规律测试台架,分析起动过程中,不同转速工况条件下,喷油泵端压力、喷油速率和喷油持续期的变化规律,结果随着起动过程喷油泵转速的升高,泵端压力的峰值增大36.18%,峰值相位前移-13.9°(CA),喷油速率加快。喷油泵转速稳定后,泵端压力曲线和喷油速率曲线形状也随之稳定,喷油速率的变化规律与泵端压力的变化规律保持一致。起动过程中,喷油持续期随平均转速的上升逐渐延长,循环喷油量趋于稳定。结论在起动工况低转速条件下,机械喷油泵的循环泵端压力峰值较小、相位靠后,循环喷油速率低且相位靠后,喷油持续期较短,同时循环喷油量较小,起动性能较差。随着喷油泵转速的上升,循环泵端压力、循环喷油速率、喷油持续期和循环供油量趋于稳定,柴油机达到更容易起动的状态。     

海拨高度对柴油机起动污染物排放的影响

以某大功率低压缩比柴油机为研究对象,进行了0,1000,2000,3000,3750,4500m 6个海拨高度的起动排放试验,研究了该柴油机不同海拨高度下起动过程中的HC,CO,NO_x和颗粒物排放特性.结果表明：海拨升高,柴油机起动过程的HC,CO和颗粒物排放增加,NO_x排放降低;与平原（0m海拨）比较,该柴油机高原（4500m海拨）冷起动排放的HC,CO和颗粒物分别增加7.1,2.6和2.1倍,NO_x降低53.8%;0~4500m海拨,该柴油机起动过程排放的颗粒物中聚集态颗粒物质量占94%~99%,颗粒物数量呈单峰对数分布,峰值粒径随着海拨的升高向大粒径方向移动,几何平均粒径增大.     

柴油烃族组分对柴油机排放的影响

柴油烃族组分可影响柴油的理化特性,从而影响柴油机的燃烧过程,进而对排放产生重要影响.本研究针对烃族组分含量不同的14种柴油,开展了排放特性的试验研究,基于试验结果采用主成分分析法及回归分析法揭示影响柴油机排放性能的关键组分及作用规律,并得到了柴油机排放与关键组分的经验公式,可在一定程度上预测排放特性.分析结果表明,总芳烃是影响柴油机排放的关键组分,当其含量介于5%～17%时,可使NO_x、soot(碳烟)、CO、HC排放均处于较低水平.此外,多环芳烃对柴油机排放有重要影响,其中的苊类、苊烯类对NO_x、碳烟、CO排放的影响作用更为显著,而其他烃族组分与柴油机排放的规律性相对较差.不同工况下,柴油机排放规律有所不同,在低负荷下柴油机排放对总芳烃含量更加敏感.     

Ignition advancement study for optimized characteristics of a raw biogas operated spark ignition engine

In the current investigation, raw biogas obtained from rural sectors was used as the alternative to gasoline fuel in the spark ignition (SI) engine. The performance and efficiency are mainly dependent on the combustion phasing for which “ignition timing” is an effective tool in a SI engine. Hence, the objective of the present work is to understand the effect of “variable ignition timing” for a biogas-fueled SI engine. For this purpose, a single cylinder, 4-stroke, SI engine of rated power 4.5 kW was operated with raw biogas at a compression ratio (CR) of 10. By maintaining a speed of 1650 rpm, the engine was operated in wide open (WOT) and part throttle (PT) mode with an equivalence ratio of 0.81 and 0.83, respectively. It was observed that the biogas fueled SI engine was found to be operative only within the ignition advance (IA) range of 33–47° CA bTDC both in WOT and PT conditions. The results showed optimal brake power (BP), brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) are achieved at 45° CA bTDC. The average peak cylinder pressure, neat heat release rate (NHRR) and mean gas temperature (MGT) are also observed to be maximum while CO and HC emission at this point of IA were found to be minimum. Due to controlled and complete combustion, CO₂ and NO_x concentration in the exhaust emission were found to be higher at this point of ignition timing.     

Electrochemical NOx reduction and oxidation of HC and PM emissions from biodiesel fuelled diesel engines using electrochemically activated cell

NOx emission is produced during combustion of fuels at high temperature. Excessive release of NOx causes several effects on living organisms and environment. In this work, the efforts to reduce NOx emission by developing electrochemically activated cells (EACs) for a diesel engine fuelled with diesel and biodiesel fuel are discussed. EAC technique is vital after treatment technology attempted in this work to simultaneous control of NOx, HC, and PM emissions. In this method, two types of EACs were developed. The CuO–YSZ electrolyte and CuO–YSZ electrolyte with BaO coating were developed and tested with diesel and biodiesel exhaust. Compared with diesel fuel, use of biodiesel fuel increased NOx emission by 11% and PM emission was slightly reduced with biodiesel, which was due to the presence of fuel bond oxygen content in biodiesel. The investigation has demonstrated low-temperature activation of the EACs at 250–350°C which was due to the addition of CuO to YSZ. In this work, maximum NOx reduction was achieved for CuO–YSZ cells with BaO NOx storage and the simultaneous control of HC and PM emission also was observed in this technique. NOx reduction by EAC is a vital technique and can be retrofitted with any diesel engine for emission reduction.     

Thermodynamic-dynamic analysis of gamma type free-piston stirling engine charged with hydrogen gas as working fluid

ABSTRACT

In this study, the combined thermodynamic and dynamic model of a new concept of gamma type free-piston Stirling engine is conducted. The engine consists of two identical displacer cylinders, a power cylinder, a linear alternator, and three-cushion pistons. Two displacer cylinders are symmetrically positioned on each side of the power cylinder for minimizing the rotational vibrations. Hydrogen is used as the working gas and the effect of gas temperature on the specific heat capacity is considered. The analysis carried out in this study involves the prediction of the thermodynamic-dynamic performance characteristics of the engine. In the thermodynamic section of the analysis, the working space of the engine is divided into 31 nodal volumes and the gas pressures in nodal volumes are assumed to be equal to each other. The conservation of mass and energy equations is obtained for each nodal volume. Instantaneous gas temperatures of nodal volumes are calculated by the first law of thermodynamics given for the unsteady open systems. The dynamic section of the analysis involves the motion equations of displacer, power and cushion pistons. The motion equations are derived using the Newton method. In the calculations done for variable specific heat capacity, it has been determined that there is 1% cyclic work reduction compared to the constant heat capacity. It is estimated that the maximum effective power that can be produced by the linear alternator will be around 1.6 kW. The working frequency range of the proposed engine is found to be suitable to generate electrical power.