汽车尾气三效催化器排气系统冷启动阶段数值模拟

发动机冷启动状态汽车尾气的排放情况对尾气排放控制起着关键的作用,建立了发动机冷启动状态排气系统传热、传质的非稳态单通道数学模型,通过对模型的数值求解,分析了汽车尾气排气系统温度、浓度的演变,经与实验结果对比,模型拟和与实验值能很好吻合,所建模型和选择参数正确.模拟了催化器内尾气温度场、浓度场的分布情况,对催化器的研究、设计具有重要意义.     

纳米金刚石发动机油明显改善尾气排放

我国大气污染非常严重,汽车是污染物排放总量的主要贡献者,其排放的CO和HC超过80%,NOx和PM超过90%。文章介绍了减少尾气排放的3种措施:机内控制法、机外控制法和介于二者之间的尚未得到普遍认可的改善气缸密封性法。使用纳米金刚石发动机油的油膜承载能力约提高1.5倍,从而密封性大为改善,同时减少车辆尾气排放的各种有害物质可达两成到六成,这一颠覆性创新是投资少见效快的最佳方案,是减少大气污染的有力措施,并且可与尾气催化器兼容。     

交错通挡板检测室在尾气遥测动态模拟实验中的应用

机动车尾气遥测系统是可在车辆正常运行状态下完成汽车尾气排放检测的设备。该类设备的校准需要对尾气含量进行精确测定。通过配备有气体光谱分析校准仪的交错通挡板检测室,可实现对开放的光程上气体的形成气团,进行更快速地分析、检测;同时能够更典型地反映如机动车运动过程中,即动态情况下尾气气团的污染的物理化学变化状态,具有广阔的应用前景及数据精度。     

M85车用燃料的排放特性及催化特性研究

为缓解我国能源危机和环境污染,加深人们对M85甲醇汽油的认识,本文通过大量发动机台架试验和尾气催化转化试验,定量和定性对M85的常规排放和非常规排放进行了分析。其中,对非常规排放不但详细分析了其产生机理和负荷特性而且简单介绍了试验设备和方法。为了便于说明问题,在相同的试验条件下分别与汽油进行了对比。最后基于催化剂剂老化机理分析如何进一步减少尾气排放,尤其是非常规排放。结果表明M85对汽油在常规排放方面有很大改善。非常规排放,通过专用的催化器完全可以消除影响。研究表明M85燃料应该得到全面的推广。     

基于OBD‐II端口的新型无线汽车故障检测系统的市场推广分析

OBD-II端口的新型无线汽车故障检测系统,是通过智能手机的蓝牙与车辆的OBD-II设备进行无线通信,来帮助驾驶员或维修人员来监控发动机的运行状况并诊断故障,指出了发动机失火的原因和危害;分析了OBD失火诊断监测方法、诊断原理和故障处理方法,同时读取该车辆的瞬时尾气排放数值和平均尾气排放数值与车辆的身份标识信息,通过有线或无线网络,将此信息送到监控中心数据库,监控人员可以准确掌握监控地区的车辆尾气排放情况,并可以及时通知尾气排放超标的车辆进行处理,大大提高了城市车辆尾气排放监控的效率。     

尽快变革和创新我国现行燃油标准是大势所趋

交通领域节能是我国节能工作中的重要领域之一。多年来燃油消耗浪费及汽车尾气污染物排放严重,一直是制约交通领域节能减排的突出问题,而发动机的性能和燃油的品质,直接影响着燃油的消耗量和尾气污染物排放量。相同的汽车,使用不同品质的燃油,其耗油量和污染物排放量大不相同。如果在改善发动机性能的同时提高燃油品质,对降低燃油消耗和减少汽车尾气污染物排放,将会带来事半功倍之效。     

控制形貌可提高催化剂性能

中科院大连化学物理研究所通过控制金属氧化物纳米粒子尺寸和形貌,首次实现了金属氧化物催化一氧化碳低温氧化的高活性和高稳定性,该成果将在降低机动车尾气排放和空气净化环保应用等方面发挥作用。科研人员将该催化剂用于汽车尾气净化过程。一氧化碳是汽车冷启动阶段排放尾气中的主要污染物之一,低温催化氧化一氧化碳是目前消除它的有效方法。传统催化剂虽然能够在低温下有效消除一氧化碳,但是在常温下活性不高,而且在微量水汽存在下快速失活。贵金属催化剂使用温度则需要在100℃以上。     

油田水井施工过程中如何利用汽车尾气余热防止防喷盒冻结电缆的设想

为了解决水井冬季施工防喷盒冰冻电缆的问题。通过对汽车尾气余热的研究分析,得到井场各发动机的尾气排量及排放温度的数据。科学设计出防喷盒外部保温包壳,回收尾气余热用以解决冬季水井施工时防喷盒结冰将电缆冻结问题。     

论汽车发动机技术、尾气排放与燃油质量关系

随着能源危机和车辆排放控制要求的日趋严格,节能和环保、动力足成了当前汽车工业研发新型汽车的方向,然而燃油质量日益成为制约汽车新技术发展及尾气排放的重要因素,并对汽车发动机的性能和尾气排放影响巨大。本文,我们对燃油质量与汽车发动机技术及环境保护的关系问题进行了分析,总结了燃油质量与发动机技术和尾气排放关系。     

天津米克尔工贸研制出新型的纳米离子润滑油

天津市米克尔工贸有限公司研制出的纳米离子润滑油，由于基础材料经纳米技术加工，使纳米离子润滑油的物理性能发生改变，与传统润滑油相比，增强了抗磨性及抗氧化性，突破了机动车更换润滑油周期。在减少机动车尾气有害物排放、降低燃油消耗、延长发动机使用寿命、发动机冷启动等方面都有重要突破。尤其突破了机动车润滑油必须5000公里至10000公里更换的常规，实现了5万至20万公里超长换油周期。     

速度分布对三效催化器性能的影响(Ⅰ)数理模型

描述了三效催化器的流动、传热传质和异相催化过程,分析了催化器的径向热导率的修正方法,比较了尾气分别作为双组分和多组分混合物时对其组分扩散系数的影响,集成了可用于模拟三效催化器的冷起动性能和暖机性能的二维轴对称瞬态模型,模型采用有限容积法求解.该模型可用于模拟和解释一维模型无法做到的流动分布等参数对催化器性能的影响.计算结果和分析在本研究中的第二部分叙述.     

Kinetics of the Steady-State Acetylene Oxidation by Oxygen over a Pt/Rh/CeO2/γ-Al2O3 Three-Way Catalyst

The steady-state kinetics of acetylene oxidation has been studied in the framework of automotive exhaust gas catalysis over a commercially available three-way catalyst. Experiments under cold-start conditions have been carried out in a laboratory fixed-bed reactor, which can adequately be described by the developed elementary step model and rate parameters.     

Gas-liquid and gas-liquid-liquid reactors with top and bottom blowing: I. Fluid dynamic regimes

The hydrodynamics of G-L and G-L-L0 reactors with top and bottom blowing is investigated. The reactor is a cold model of a 250 ton industrial converter, the different phases present in the real converter (steel-slag-gases) were simulated employing the triphasic system water-vaseline-air; this system was selected to maintain not only the fluidynamic similarity between both reactors. The behaviour of each phase with respect to the other phases employing different top and bottom gas flow rates was analysed. Thus, the formation of gas bubbles in the bulk of the liquid phase (important in the study of G-L mass transfer and in the mixing field), emulsions and drops (important in L-L0 mass transfer) and the streamlines in the reactor were studied to better understand the refining process in the real converter. We also propose flow regime maps with coupling of the different regimes for the three phases present in the reactor, when the gas flow rate is modified.     

GAS-LIQUID AND GAS-LIQUID-LIQUID REACTORS WITH TOP AND BOTTOM BLOWING: I. FLUID DYNAMIC REGIMES

The hydrodynamics of G-L and G-L-L0 reactors with top and bottom blowing is investigated. The reactor is a cold model of a 250 ton industrial converter, the different phases present in the real converter (steel-slag-gases) were simulated employing the triphasic system water-vaseline-air; this system was selected to maintain not only the fluidynamic similarity between both reactors. The behaviour of each phase with respect to the other phases employing different top and bottom gas flow rates was analysed. Thus, the formation of gas bubbles in the bulk of the liquid phase (important in the study of G-L mass transfer and in the mixing field), emulsions and drops (important in L-L0 mass transfer) and the streamlines in the reactor were studied to better understand the refining process in the real converter. We also propose flow regime maps with coupling of the different regimes for the three phases present in the reactor, when the gas flow rate is modified.     

CATALYTIC CONVERTER DESIGN FOR MINIMISATION OF COLD-START EMISSIONS

The axial catalyst distribution in a monolithic converter that minimises cold-start pollutant emissions is investigated numerically, under the constraint of fixed total catalyst surface area. Various warm-up mechanisms can be present during the transient period. The catalyst distribution affects greatly which mechanisms prevail. For the optimal distribution, a large amount of catalyst is required in the upstream section of the monolith This ensures that the hot spot is kept at the monolith inlet throughout the warm-up period, and hence heat transfer by convection dominates. A result of practical significance is that the evolution and the steady-state value of the temperature of the exhaust gas stream at the monolith inlet do not affect significantly the form of The optimal distribution. Even though the local catalyst surface area of the optimal distribution in the downstream section of the converter is reduced as compared to the uniform distribution, steady-state performance is not adversely affected. A converter with two-zones, each having a different but uniform catalyst loading is also examined. It is shown that such a design can closely approximate the optimal distribution. Finally, performance degradation due to sintering is shown to be more severe for The case of the uniform catalyst distribution.     

压铸及压制模中排气槽的设置

介绍压铸及压制模中排气槽设置的重要性，排气槽断面积计算公式、推荐尺寸，以及排气槽确定原则。     

住宅厨房排烟的共用竖烟道的设计方法改进

分析了现代住宅厨房采用共用竖烟道排烟系统的运行特点:排烟动力主要来源于排油烟机提供的风压,热压的作用很小;提出了住宅厨房集中排烟系统"控制最小排烟量"的设计方法。该方法是将排烟系统中最小排烟量确定为某数值,通过求解非线性方程组确定竖烟道截面积。"控制最小排烟量"的设计方法能客观地反映集中排烟系统的运行特点,确保排烟系统中每户厨房排烟均达到要求。此方法在江苏省住宅厨房集中排烟系统建筑图集新标准的制订中得到应用。     

On the quantification of the controlling regimes in automotive catalytic converters

The conversion of pollutants in automotive catalytic converters is influenced by a number of physical and chemical processes that take place in the gaseous and solid phases as the exhaust gases flow through the converter. A detailed understanding of the complex processes involving flow dynamics, heat and mass transport and heterogeneous surface reactions is of crucial importance to improve the converter design. The main objective of the present study is to quantify the magnitudes of the external and internal mass transfer as well as chemical reaction limiting processes as a function of the converter operating temperature. To this end, experimental data, obtained for a three way catalyst (TWC) under real world operating conditions, are analyzed and compared against analytical expressions that allow for the quantification of the different limiting processes involved. The results demonstrate that (i) the external mass transfer resistance overlaps the reaction resistance only at moderate operating temperatures and not immediately above the ignition temperature as generally considered in the literature, (ii) the transport phenomena (external and internal mass transfer) represents 90% of the total resistance for temperatures higher than 792 K, (iii) the internal mass transfer in the porous washcoat presents a larger resistance than the external mass transfer from the bulk fluid to the washcoat wall even at high operating temperatures, and (iv) based on the quantification of the individual resistances as a function of the TWC operating temperature, it was demonstrated both the influence of the substrate cell density and of the effective diffusivity on the TWC conversions. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Axial characterization of catalytic activity in close-coupled lightoff and underfloor catalytic converters

A exhaust system consisting of a close-coupled Pd technology 32 in³ lightoff converter and Pt/Rh technology 170 in³ underfloor converter was vehicle-aged for 56000 miles on a vehicle equipped with a 3.8 l engine. Following this aging, the converters were taken off the vehicle and cut into 1″ thick sections along their axis and characterized for lightoff and warmed-up activity using a laboratory reactor to simulate vehicle exhaust. Each section was also analyzed for the quantity of oil additive poisons (phosphorus and zinc) deposited. Following this initial characterization, the phosphorus and zinc deposits were removed, and the sections were characterized again for lightoff and warmed-up activity. This procedure was used to qualitatively determine the relative contribution of oil additive poisoning and thermal sintering to the total activity deterioration as a function of axial position in the catalyst monoliths.

Analysis of the lightoff converter as taken from the vehicle showed a dramatic axial gradient in the lean and stoichiometric lightoff and warmed-up (600°C) performance for HC, CO and NO_x, with most of the deterioration having taken place in the forward-most 1″ section of the converter, which was consistent with the gradient in the deposition of phosphorus (P) and zinc (Zn) in this converter. Comparison of these data sets with those obtained after removal of the P and Zn poisons indicates that most of the total deterioration of lean HC and CO activity can be attributed to P and Zn poisoning of the forwardmost 1″ section. When tested under stoichiometric conditions, most of the deterioration of HC activity is attributable to P and Zn poisoning, while most of the deterioration of CO and NO_x activity is attributable to thermal deterioration. A similar activity and poison deposition gradient was detected in the underfloor converter, but to a smaller extent.