共查询到17条相似文献,搜索用时 187 毫秒
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柴油机排气中的微粒物质对环境和人体健康有极坏影响。本文作者采用稀释通道、热重分析仪,测量了S195柴油机微粒排放的质量浓度,对微粒中的碳和碳氢化合物两种组分进行了分析。作者还使用蜂窝陶瓷过滤排气中的微粒,用燃油添加刑的方法对过滤器进行催化再生。结果表明,过滤器可大幅度减少微粒排放量。燃油添加剂再生效果好,对柴油机的排放和经济性影响不大。与电加热再生相比,燃油添加剂催化再生简单、可靠,具有较大的应用价值。 相似文献
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直喷式柴油机排放微粒尺寸分布特性 总被引:4,自引:0,他引:4
在一台单缸柴油机上用SMPS微粒测量装置测量了不同运转条件(如转速、负荷变动、怠速运行、燃油喷射定时等)下柴油机排放微粒尺寸与浓度分布,分析了柴油机微粒排放尺寸分布和数量浓度的特征及其主要影响因素.结果表明,发动机负荷变化对微粒排放的影响较大,在各种负荷下大部分排放微粒都是碳核模式的超细或纳米尺寸微粒,而质量上以累积模式颗粒占主要部分,发动机冷机起动和怠速运行时产生的大部分排放微粒是碳核模式粒子,喷油提前角对排放微粒浓度和尺寸分布有显著影响. 相似文献
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Diesel exhaust particles have a negative impact on both human health and the ecosystem. An adequate understanding of the physical and chemical characteristics of diesel exhaust particles is essential for both minimizing particles formation and optimizing particles oxidation. This paper systematically reviews the physicochemical characteristics of diesel exhaust particles. Firstly, the approaches to studying the characteristics of diesel exhaust particles are described and the main features of particulate matter (PM) such as particle size distributions, microstructure of aggregate particles, nanostructure of primary particle, chemical compositions of diesel particles and oxidation reactivity of diesel particles are discussed in this paper. Then, the effects of operating parameters containing engine speed, engine load, injection pressure, injection timing and exhaust gas recirculation (EGR) on each PM feature are summarized and discussed in detail. Subsequently, the relationships between PM features and its oxidation reactivity are exclusively reviewed. It can be concluded that soot oxidation reactivity is influenced by the combination of multiple properties of the emitted PM. Finally, concluding remarks are presented and further research recommendations are listed. 相似文献
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This article presents a numerical simulation procedure for studying soot particle deposition in diesel exhaust systems, with a particular focus on fouling layer thickness evolution. In the proposed algorithm, particle transport toward the wall, adhesion, and reentrainment of particles from the surface have been modeled, including Brownian motion and turbulent diffusion, thermophoresis, adhesion, and removal. This model has been implemented in ANSYS Fluent, which makes the inclusion of local effects possible. A cross-flow device, with a tube positioned transverse to the flow, has been simulated and tested. A comparison of the predicted fouling layer at several angular positions with the experimental observation shows acceptable agreement. This model makes it possible to predict the real depth of the fouling layer and its effects on the hydrodynamics of the flow. This model represents a valuable tool for the prediction of the main aspects of the performance of heat exchangers exposed to fouling. 相似文献
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声波团聚脱除柴油机尾气中超细颗粒物的试验研究 总被引:3,自引:0,他引:3
利用低频率高强度声场试验装置,进行了脱除柴油机尾气中超细颗粒物的试验研究.由电称低压冲击器ELPI实时在线测量烟气中颗粒浓度在声波作用前后的变化,系统研究了声场强度、停留时间和颗粒数目浓度对细颗粒脱除效率的影响.结果表明,低频高强声场对柴油机尾气中的超细颗粒具有较高的团聚清除效果,提高声场强度、适当延长停留时间和增大初始颗粒数目浓度均有利于颗粒物的声波团聚脱除.当声波频率为1 kHz、团聚窜内声场强度达到161.5 dB时,0.023~10 μm粒径的颗粒数目浓度可减少55.7%.试验结果表明低频高强声波场是一种控制柴油机尾气中超细颗粒排放的有效方法. 相似文献
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排气背压对柴油机的动力性能和油耗有着重要的影响,排气背压过大会造成动力性能的损失和油耗的增加,因此,在为柴油机设计排气后处理装置时,要充分考虑排气背压的大小。本文针对水下工作的柴油机,设计了一套排气降温系统,可以使得该柴油机在水下工作时,其排气可以被冷却后直接排向大气,并且其动力性能不受影响,这就要求在设计过程中要使整个排气降温系统的流动阻力尽可能最小。通过试验结果表明:加装该排气降温系统后柴油机输出动力性能良好,无功率和转矩损失;特殊管壳式换热器换热效果良好,能使最高温度为503.4℃的高温烟气降低到39.4℃。本文研究的结果对小型水下动力装置排气降温系统的选择和设计有一定的参考价值。 相似文献
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测量了轻型柴油车在高怠速和低怠速运转的条件下,其尾气烟羽中粒径范围在15nm到30μm的颗粒数量和粒径的分布。利用SMPS和APS测量装置测量尾气烟羽中心线和环境背景条件下的颗粒排放。测量结果表明,测试的柴油车在高怠速运转的条件下会排放出更多的颗粒。然而,在两种怠速条件下,总的颗粒数量浓度由于沉降的作用会随着远离排气管的距离而减少。测量结果还表明,柴油车排放的颗粒主要是粒径小于700nm的颗粒,这些细颗粒比粗颗粒更易长期悬浮于大气中,从而引发局部的颗粒物污染问题。 相似文献