摩托车催化转化器性能台架评价方法研究

台架评价试验在摩托车催化转化器性能评价体系中起重要的作用，但国内摩托车催化转化器性能台架评价目前尚属空白。在借鉴国内外汽车催化转化器台架评价试验方法的基础上，建立了摩托车催化转化器性能台架评价试验装置，并进行了催化转化器空燃比特性、空速特性、温度特性、起燃时间特性试验。     

摩托车催化转化器性能台架评价装置改进及试验研究

针对原摩托车催化转化器台架性能评价存在控制精度不高及调整不方便的缺点,对评价试验装置进行了改进。采用电控系统控制空燃比,设计了翅片管式换热器调节催化器入口温度。试验表明,改进后空燃比的波动可控制在0.1以内,入口温度波动在±2℃以内。利用该台架对MLKV 102-2催化器的性能进行了研究,试验结果表明该台架可以快速有效地评价催化器的性能。     

摩托车催化转化器性能台架评价试验研究

台架评价试验在摩托车催化转化器性能评价体系中起重要的作用。根据摩托车催化转化器的特点，参照汽车催化转化器台架评价试验方法，建立了摩托车催化转化器性能台架评价试验装置，用该装置进行了催化转化器空燃比特性，空速特性，温度特性，起燃时间特性等试验，为摩托车采用催化转化器提供了有效的技术支持和评价手段。     

摩托车催化转化器性能台架考核装置改进

摩托车催化转化器性能台架考核方法,可以快速有效的评价催化器的性能.在本文中对原有的试验装置进行了改进.设计了电喷系统对空燃比进行调节,设计了换热器对催化器入口温度进行调节.试验结果证明改进后的装置可以提高空燃比和入口温度的控制精度,满足快速准确的评价催化器性能的要求.     

摩托车催化转化器性能台架考核装置改进

摩托车催化转化器性能台架考核方法,可以快速有效的评价催化器的性能。在本文中对原有的试验装置进行了改进。设计了电喷系统对空燃比进行调节,设计了换热器对催化器入口温度进行调节。试验结果证明改进后的装置可以提高空燃比和入口温度的控制精度,满足快速准确的评价催化器性能的要求。     

摩托车台架实验空燃比控制系统的开发

本文介绍了用于摩托车台架实验的空燃比控制系统,可用于在台架上进行摩托车催化器性能的考核。系统主要分为上位机和下位机两部分,下位机控制喷油时刻喷油持续期及喷油量,从而实现了对空燃比的控制;上位机可以完成各种参数的监测和采集。     

摩托车台架实验空燃比控制系统的开发

本文介绍了用于摩托车台架实验的空燃比控制系统,可用于在台架上进行摩托车催化器性能的考核.系统主要分为上位机和下位机两部分,下位机控制喷油时刻喷油持续期及喷油量,从而实现了对空燃比的控制;上位机可以完成各种参数的监测和采集.     

两种天然气专用氧化型催化器的对比试验研究

对两种天然气专用氧化型催化器进行了空燃比和起燃温度特性试验,对比并分析了试验结果,初步了解了两种催化器对天然气发动机排放的净化能力以及它们之间的性能差异。     

摩托车尾气净化催化剂耐久性试验

描述了所制金属载体催化剂的性能,包括γ-Al2O3涂层比表面积、起燃温度、空燃比和涂层脱落问题,并对试验数据作了分析.结果表明,该催化剂新鲜样品低温起燃且三效耦合性能和空燃比特性均很好,但经历快速老化和水热老化试验后,性能相对变差;涂层脱落率很低,达到0.971%,远远低于6%,为更长的耐久性提供了有利支撑.     

三效催化转化器快速老化过程性能仿真

基于三效催化转化器详细化学反应机理以及老化机理,建立了包含老化过程的三效催化转化器表面动力学模型,并与CFD软件相耦合,根据100h快速老化试验条件,建立了三效催化转化器快速老化过程的二维单孔道老化特性模型.对该模型进行数值仿真,得到了特征转化效率随快速老化时间的变化规律以及老化前后三效催化转化器的起燃特性、空燃比特性曲线.结果表明:仿真结果与试验结果基本一致,这为三效催化转化器的老化过程性能分析提供了有效的理论方法.     

基于OBD系统故障模拟装置的开发与研究

基于OBD系统必须监测的失火故障及氧传感器故障,提出了1种新型的失火方式及氧传感器故障模拟方式,设计并开发了1套集失火故障模拟和氧传感器故障模拟于一体的故障模拟装置。通过台架试验和实车试验验证了故障模拟装置的可靠性、准确性及通用性,研究了失火故障对发动机转速、空燃比的影响和氧传感器故障对空燃比的影响。结果表明:在发动机转速分别为1500 r/min和2500 r/min、节气门开度为20%时,以2%和4%的失火率来控制发动机失火时,失火控制精确;空燃比因气缸失火而升高;不同氧传感器故障对空燃比的影响程度有所区别,时间延迟对空燃比的影响最明显。     

催化重整反应对柴油掺水燃烧中着火的影响

研究了催化重整反应对柴油掺水燃烧中着火温度的影响，以及有无催化重整时，着火温度的变化，从实验结果中可看出催化重整反应对乳化柴油着火有显著的影响，能够显著降低着火温度。详细介绍了实验的装置、过程及结果，并对实验结果进行了解释和分析，最终得出催化重整反应能够降低乳化柴油着火温度的结论，并提出了催化重整能够发生的两个必要条件。     

Ignition propensity of hydrogen/air mixtures impinging on a platinum stagnation surface

An experimental investigation into the ignition characteristics of lean pre-mixed hydrogen/air mixtures is conducted using a stagnation-point flow configuration against a platinum surface, with a special emphasis on the determination of potential fire safety hazards associated with hydrogen release in the presence of a catalyst. Two distinct regimes are observed for this system – catalytic surface reactions and gas-phase ignition. It is demonstrated that depending on mixture equivalence ratio, catalytic surface reactions can be initiated with or without surface heating. When significant surface heat is released via catalytic reactions, gas-phase ignition can be induced, greatly increasing the apparent danger of hydrogen leaks in the presence of a platinum surface. The critical surface temperatures leading to catalytic ignition for hydrogen/air mixtures over a platinum surface are further investigated over a range of equivalence ratios and stretch rates. It is shown that ultra-lean hydrogen/air mixtures can be catalytically ignited even in the absence of external heat addition, suggesting that hydrogen leakage in the presence of a platinum surface may pose a fire safety risk even at room temperature. Furthermore, even without a transition to gas-phase ignition, the surface temperature that can be sustained with surface reactions alone may contribute to component degradation or itself pose a safety hazard.     

Characteristics of hydrogen-assisted catalytic ignition of n-butane/air mixtures

External heating and hydrogen-assisted catalytic ignition characteristics of n-butane (n-C₄H₁₀) were studied experimentally in a Pt-coated monolith catalytic reactor. Special attention was paid to the chemical effect of hydrogen on hydrogen-assisted ignition. A comparison of the ignition temperature for these two ignition methods shows hydrogen can lower ignition temperature. Furthermore, the ignition experiment at low hydrogen mole fraction (1.5%) shows that hydrogen has a positive chemical effect on hydrogen-assisted ignition. At constant n-butane/air flow and within certain limits of hydrogen mole fraction of mixtures, the ignition temperature changes little, whereas the time required for ignition and the cumulative amount of hydrogen decrease substantially. Consequently, high hydrogen mole fraction is favorable to hydrogen-assisted ignition. Two startup methods and thermal insulation are discussed. The co-feed method (n-butane/air/hydrogen mixtures are fed into reactor) and thermal insulation were found to be beneficial to hydrogen-assisted ignition.     

Validation of measured data on F/A ratio and turbine inlet temperature with optimal estimation to enhance the reliability on a full-scale gas turbine combustion test for IGCC

This study is aimed at verifying the reliability and reproducibility of combustion tests, including ignition, load change and fuel changeover, conducted at a well-resourced full-scale gas turbine syngas combustion test facility. The 10 MWth, single-can, syngas-fired combustion test facility was equipped with analytical equipment to measure air and fuel flow rates to the combustor, the metal/gas temperature in the combustor, and exhaust gas composition and temperature distribution at the combustor's outlet.To confirm the test facility's reliability, the repeatability of the fuel changeover test from natural gas to syngas was evaluated. Reliability was also verified by cross-validating the theoretical and measured values for fuel/air (F/A) ratio and Turbine Inlet Temperature (TIT). In this study, the deviation between the averaged F/A ratio based on O₂ and CO emission data and the F/A ratio based on the mass flow rate was under 2% at most, when the F/A ratio exceeded 20%. And, the calculated TIT for syngas, taking thermal dissociation and heat loss into consideration, correlates well with the experimental result which is the corrected TIT value based on heat balance at the temperature sensor tip.     

Simulation of hydrogen and hydrogen-assisted propane ignition in pt catalyzed microchannel

This paper deals with self-ignition of catalytic microburners from ambient cold-start conditions. First, reaction kinetics for hydrogen combustion is validated with experimental results from the literature, followed by validation of a simplified pseudo-2D microburner model. The model is then used to study the self-ignition behavior of lean hydrogen/air mixtures in a Platinum-catalyzed microburner. Hydrogen combustion on Pt is a very fast reaction. During cold start ignition, hydrogen conversion reaches 100% within the first few seconds and the reactor dynamics are governed by the “thermal inertia” of the microburner wall structure. The self-ignition property of hydrogen can be used to provide the energy required for propane ignition. Two different modes of hydrogen-assisted propane ignition are considered: co-feed mode, where the microburner inlet consists of premixed hydrogen/propane/air mixtures; and sequential feed mode, where the inlet feed is switched from hydrogen/air to propane/air mixtures after the microburner reaches propane ignition temperature. We show that hydrogen-assisted ignition is equivalent to selectively preheating the inlet section of the microburner. The time to reach steady state is lower at higher equivalence ratio, lower wall thermal conductivity, and higher inlet velocity for both the ignition modes. The ignition times and propane emissions are compared. Although the sequential feed mode requires slightly higher amount of hydrogen, the propane emissions are at least an order of magnitude lower than the other ignition modes.     

Experimental investigation on propagation characteristics of liquid-fuel/preheated-air rotating detonation wave

The rotating detonation combustor can be applied to the turbine engine to develop into a new power device, and the liquid-fuel/air rotating denotation has important research significance for engine applications. In this research, the propagation characteristics of liquid-fuel/air rotating detonation wave were experimentally investigated. A hydrocarbon mixture—liquid gasoline was employed for the fuel, the oxidizer was high-temperature air preheated by a hydrogen-oxygen heater, and the rotating detonation wave was initiated via a hydrogen-oxygen pre-detonator. The effects of the equivalence ratio, ignition pressure, and air total temperature on the propagation characteristics of the liquid-fuel rotating detonation wave were analyzed. The liquid-fuel/air continuous rotating detonation wave can be successfully obtained with a single-wave mode, and the velocity and peak pressure of the rotating detonation waves increase as the equivalence ratio increases. As the detonation-wave pressures at the outlet of the pre-detonator increase, the establishment time of the rotating detonation wave gradually decreases, and the average establishment time is 4.01 ms. Stable rotating detonation waves are obtained with the air total temperature of 600–800 K, but the intensity of the detonation wave has a large deficit due to some instabilities.     

Enhancement of heat recirculation on the hysteresis effect of catalytic partial oxidation of methane

The hysteresis characteristics of catalytic partial oxidation of methane (CPOM) in a Swiss-roll reactor are predicted numerically by varying Damköhler number. Particular attention is paid to the influences of heat recirculation, gas hourly space velocity (GHSV), and atomic O/C ratio on the hysteresis loop and performance of CPOM. The reactions of methane combustion, steam reforming, and CO₂ or dry reforming are simultaneously considered. The results reveal that preheating reactants through excess enthalpy recovery is conducive to the ignition of CPOM and extending its extinction limit, so the ignition and extinction Damköhler numbers are lowered. The analysis also suggests that steam reforming is more sensitive to the heat recovery than methane combustion and dry reforming. An increase in GHSV reduces the residence time of reactants in the catalyst bed, thereby enlarging the ignition and extinction Damköhler numbers of CPOM. A higher O/C ratio facilitates the ignition of CPOM, stemming from more oxygen supplied, but the ratio should be controlled below 1.2. From the hysteresis phenomena, hydrogen can be produced from methane at a lower Damköhler number to save more energy for performing CPOM.