机动车尾气遥测技术和应用研究

机动车尾气已经成为很多大中城市的主要气体污染源之一,利用基于光谱学的遥测技术可以在不影响车辆正常行驶的条件下快速检测出尾气超标车辆.自行研制的尾气遥测系统结合了可调谐二极管激光吸收光谱(TDLAS)和差分吸收光谱(DOAS)技术,实现了对尾气中CO、CO2、HC、NO和烟尘等污染物的实时测量,并同时识别牌照和采集车辆行驶信息.     

机动车尾气CO和CO2非分光红外遥测技术研究

利用分子红外光波段的吸收光谱特性，本文研究了机动车尾气CO和CO2的快速响应非分光红外(non-dispersion infrared)遥测技术，系统采用单个红外探测器测量CO、CO2和背景，微弱信号的检测采用光斩波器与锁相放大器的组合以及接收和发射一体的系统结构，克服了传统技术检测精度低、无法检测行进中机动车排放的尾气等缺点．本文还研究了静态条件下气体浓度和测量信号之间的关系，动态测量表明该技术可以完全非接触在线自动监测机动车行驶过程中排放的尾气．     

排查尾气超标车启用激光电子眼

“只需0．7S，过往机动车的一氧化碳排放数值及车牌号就会立刻显示在电脑上，尾气超不超标一目了然。”近日，有3辆运用高科技手段的激光遥测监测车投入北京的大街小巷，对过往车辆的尾气进行实时监测，这是北京市第1次使用装有“电子眼”的高科技监测车替代传统的人眼“看”尾气。据市环保局有关负责人介绍，过去的尾气监测方式比较传统：由检测人员叫住被抽查的机动车先“靠边停”，然后用肉眼观看尾气排放是否超标。这种方式不但准确率受影响，而且还必须叫被抽查的车停靠下来，费时费力。近日启用的高科技手段不但准确率可以达到100％．而且过往车辆不用停车．可以做到“过l辆测l辆”。“20年内还将增加7辆进驻各主要街道对过往机动车尾气污染进行监测。”市环保局机动车尾气排放管理处处长冯玉桥告诉记者。新闻链接环保违章将进入交通违章查询系统。     

气溶胶飞行时间激光质谱仪在机动车尾气检测中的应用

使用气溶胶飞行时间激光质谱仪(ATOFMS)对机动车排放出的尾气进行在线测量,在排放出的气溶胶单粒子中检测出包括钠、钙、CnHm等在内的有机和无机离子.实验表明可以用钙离子和一些典型的有机质谱峰作为监测机动车尾气的标记,同时说明了此装置实时在线测量机动车尾气成分的可行性,也可以为机动车尾气气溶胶粒子在大气气溶胶中的分配情况进行化学路径跟踪.     

机动车尾气CO检测中神经网络多环境因子在线修正算法研究

分析了温度、湿度、压力对预处理后尾气CO浓度测量的影响, 提出一种机动车尾气CO检测神经网络多环境因子在线修正算法, 首先采用尾气样本数据离线训练得到BP神经网络模型, 然后将实时测得的样品气温度、湿度、压力及小数吸收值代入到模型进行在线修正, 得到修正后CO浓度, 解决了NDIR传感器因环境变化所带来的测量误差影响.通过标样实验、模拟实验, 并和SEMTECH-EcoStar对比检测结果, 在样品气温度30～50℃、相对湿度25～40%、压力95～115kPa、CO浓度0～0.2%范围内的最大相对偏差为4.8%.车载外场实验, 得到修正因子在0.8～1之间, 验证了方法的必要性和可靠性, 为机动车尾气的CO浓度的准确检测提供有效技术支持.     

机动车尾气CO检测中神经网络多环境因子在线修正算法研究（英文）

分析了温度、湿度、压力对预处理后尾气CO浓度测量的影响,提出一种机动车尾气CO检测神经网络多环境因子在线修正算法,首先采用尾气样本数据离线训练得到BP神经网络模型,然后将实时测得的样品气温度、湿度、压力及小数吸收值代入到模型进行在线修正,得到修正后CO浓度,解决了NDIR传感器因环境变化所带来的测量误差影响.通过标样实验、模拟实验,并和SEMTECH-EcoStar对比检测结果,在样品气温度30～50℃、相对湿度25～40%、压力95～115kPa、CO浓度0～0.2%范围内的最大相对偏差为4.8%.车载外场实验,得到修正因子在0.8～1之间,验证了方法的必要性和可靠性,为机动车尾气的CO浓度的准确检测提供有效技术支持.     

基于半导体激光吸收谱的在线CO和CO2浓度同时测量技术

优选了中心频率分别为6338.5895cm-1和6337.99cm-1的CO和CO2吸收谱线,使用一个激光器扫描经过该对谱线,在搭建的实验系统上实现了对CO和CO2的同时测量,实验结果表明,基于半导体激光吸收谱(DLAS)的CO和CO2检测下限分别为3σ=0.042%和3σ=0.022%,CO和CO2的线性相关系数分别为0.9999和0.9996,CO和CO2相互间干扰小于1%。现场测量结果表明,该技术能够较好地满足工业过程、机动车尾气和环保等的CO和CO2浓度同时测量的需要。     

机动车尾气NDIR传感器性能仿真分析

机动车尾气检测在防治机动车尾气污染中起到十分重要的作用,非分散红外法(NDIR)气体传感器作为测量尾气CO、CO2的核心部件,其性能指标必须满足国家相关标准的要求.为了在设计的初始阶段实现对设计方案的优化和性能评估,本文提出了一种NDIR气体传感器的性能仿真分析方法,通过计算和分析NDIR气体传感器的响应函数来估算传感器可以达到的测量精度.将该方法应用于机动车尾气NDIR气体传感器的设计中,证明该方法具有一定应用价值.     

机动车尾气遥感监测数据中心平台的设计与开发

随着我国城市化建设的发展和机动车使用数量的提高,机动车尾气逐渐成为城市清洁空气的主要杀手。为有效改善城市空气污染状况,需对机动车尾气排放进行有效的控制和严格的检测。随着遥测技术的产生,在获得遥测尾气数据后,必须对检测数据进行有效安全的存储、管理及分析。针对机动车尾气遥感监测数据的存储、显示及分析处理的需求,建立了机动车尾气数据中心平台,实现对机动车尾气海量数据的存储管理以及Web监控查询平台的设计。     

基于RFID技术的江苏省机动车网络监管系统建设方案研究

针对车辆排放流动性特征,研究基于RFID技术下江苏省机动车网络监管系统搭建,通过RFID技术对机动车尾气排放检测、车辆维修、车辆路检路查、环保限行方面,对检测机构的检测行为、环保标志电子卡管理、车辆淘汰报废、定期不定期检测、强制维护等污染防治的各个环节进行管理,提高监督质量、执法效率、服务水平,并在全省范围建立环保限行区,通过环保标志电子卡对黄标车在中心城区开展信息化限行措施,实现RFID环保电子卡减排联动、机动车排气污染区域联防联控,同时亦可实现治污与治堵并举。     

Optical pumping of CO by a convective flow CO laser

A convectively cooled CO laser has been used to optically pump the vibrational distribution of CO preheated in a dc discharge. For maximum pump flux levels of 8 kW/cm², it was found that optical coupling to flowing CO could be achieved only in the presence of discharge preheating and the extent of optical pumping was a strong function of pump wavelength over the range5.0-5.1 mum. The excited CO vibrational distribution was derived by spectroscopic analysis to be similar to the highly nonequilibrium distributions obtained in prior work. Numerical calculations of the vibrational distributions have been performed and reasonable agreement with the experimental results was found.     

Remote Sensing CO,CO2 in Vehicle Emissions Based on TDLAS

Knowing the quantity of pollutants in almost every major city in China. Finding that the vehicle fleet is emitting to the air has become a vital problem and fixing gross polluters is therefore very important to control the urban air quality and protect the human health and the environment. Remote sensing is an important advance in the technology of on-road vehicle emissions testing because it is fast, mobile, and unobtrusive. This on-road vehicle emissions remote system is designed to measure the carbon monoxide, carbon dioxide and opacity from the vehicles＇s tailpipe based on the Tunable Diode Laser Absorption Spectroscopy （TDLAS）. There are several advantages of this system such as compact design and easy of use. The measurement principle and optical layout of the instrument has been described in this paper. Field testing at Beijing and Hefei were conducted over one year, more than 6 000 vehicles were tested. This vehicle emissions remote system has been shown to be able to measure CO,CO2 and opacity from individual at highway speeds. In parallel, the plate license, speed, acceleration and length of vehicle are recognised by computer so that the owners of vehicles exceeding the permissible level of emissions can be identified.     

FTIR遥测北京城区大气中的CO和CO2浓度

傅里叶变换红外光谱(FTIR)技术已经成为研究微量大气组分的有效方法.使用自行组建的开放光程傅里叶变换红外光谱系统于2005年夏季和2006年冬季对北京城区的CO和CO2浓度进行了连续观测,并对测量结果进行了分析.研究结果表明,这两种气体在冬季的浓度值均明显高于夏季浓度值,并且具有类似的变化趋势,基本趋势表现为白天低、夜间高.两次测量的结果表明,这两种气体具有较好的相关性,相关系数分别为0.896和0.856.     

CO and CO2 dual-gas detection based on mid-infrared wideband absorption spectroscopy

A dual-gas sensor system is developed for CO and CO2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing (TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode (without rotation) and dynamic mode (with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million (ppm) in volume and 2.6 ppm for CO and CO2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO2, respectively. The reported sensor has potential applications in various fields requiring CO and CO2 detection such as in the coal mine.     

CO2 Conversion Toward Real-World Applications: Electrocatalysis versus CO2 Batteries

Electrochemical carbon dioxide (CO₂) conversion technologies have become new favorites for addressing environmental and energy issues, especially with direct electrocatalytic reduction of CO₂ (ECO₂RR) and alkali metal-CO₂ (M–CO₂) batteries as representatives. They are poised to create new economic drivers while also paving the way for a cleaner and more sustainable future for humanity. Although still far from practical application, ECO₂RR has been intensively investigated over the last few years, with some achievements. In stark contrast, M–CO₂ batteries, especially aqueous and hybrid M–CO₂ batteries, offer the potential to combine energy storage and ECO₂RR into an integrated system, but their research is still in the early stages. This article gives an insightful review, comparison, and analysis of recent advances in ECO₂RR and M–CO₂ batteries, illustrating their similarities and differences, aiming to advance their development and innovation. Considering the crucial role of well-designed functional materials in facilitating ECO₂RR and M–CO₂ batteries, special attention is paid to the development of rational design strategies for functional materials and components, such as electrodes/catalysts, electrolytes, and membranes/separators, at the industrial level and their impact on CO₂ conversion. Moreover, future perspectives and research suggestions for ECO₂RR and M–CO₂ batteries are presented to facilitate practical applications.     

Thick-film CO gas sensors

A gas sensor of SnO2-based materials has been made by thick-film technology utilizing hydrophobic silica as a binder. The technology can achieve a high productivity as well as a reduced humidity dependence and a sufficient mechanical strength of sensors. A thick-film sensor of SnO2incorporated with ThO2shows highly selective detection for CO gas, separated from H2gas; i.e., sensitivity to CO is 42 times higher than to H2at both gas concentrations of 50 ppm. An excellent humidity-independent sensitivity is also achieved.     

Accelerating CO2 Electroreduction to CO Over Pd Single‐Atom Catalyst

The electrochemical conversion of carbon dioxide (CO₂) into value‐added chemicals is regarded as one of the promising routes to mitigate CO₂ emission. A nitrogen‐doped carbon‐supported palladium (Pd) single‐atom catalyst that can catalyze CO₂ into CO with far higher mass activity than its Pd nanoparticle counterpart, for example, 373.0 and 28.5 mA mg^?1_Pd, respectively, at ?0.8 V versus reversible hydrogen electrode, is reported. A combination of in situ X‐ray characterization and density functional theory (DFT) calculation reveals that the Pd? N₄ site is the most likely active center for CO production without the formation of palladium hydride (PdH), which is essential for typical Pd nanoparticle catalysts. Furthermore, the well‐dispersed Pd? N₄ single‐atom site facilitates the stabilization of the adsorbed CO₂ intermediate, thereby enhancing electrocatalytic CO₂ reduction capability at low overpotentials. This work provides important insights into the structure‐activity relationship for single‐atom based electrocatalysts.