【作者】 刘国华；

【导师】 张玉钧；

【作者基本信息】 中国科学技术大学 ， 光学， 2018， 博士

【摘要】 机动车尾气排放的CO、CO2是城市空气的主要移动污染源之一。目前,国家出台了相关政策法规,加强对尾气CO、CO2排放的监管。然而,国内检测CO、CO2排放因子的车载式设备主要依赖进口。论文开展机动车尾气CO、CO2排放因子检测系统中的关键技术研究,为CO、CO2排放因子检测设备的国产化提供技术支持。针对机动车高温尾气取样预处理的需求,研发了去水去杂小型旋风分离器、改进型尾气压差测量皮托管、多点温度测量模块、改进型样品气压差测量孔板等关键部件,设计了预处理采样气路,集成了机动车高温尾气预处理系统,达到了去除尾气中颗粒物和水分的目的,并获得了 CO、CO2排放因子中相应的尾气温度、质量流量等参数。实验结果表明,预处理后的样品气,相对湿度小于40%,温度低于50℃,所含颗粒物直径小于3μm,且含量极少,满足了车载式机动车尾气光学检测分析模块的要求。设计了检测系统标零、标量程和样品气体的气路切换与驱动模块,研发了样品气温度、湿度、压力参数检测电路;在红外吸收信号检测电路方面,研发了自适应宽量程信号检测电路、基于DSP的单频滤波电路和改进的调制光电信号差分双采样电路,实现了红外测量信号的快速、宽量程、低噪声检测,对比实验表明,高温尾气CO、CO2浓度检测系统响应时间为0.5s,相比于传统方法响应速度提高了 6倍。分析了气体温度、湿度、压力等环境因子对预处理后尾气CO、CO2浓度测量的影响规律,提出了一种基于神经网络的多环境因子在线修正算法,提高了高温尾气CO、CO2浓度的反演精度。标样实验表明:最大相对偏差从22%降至5.8%。模拟对比实验表明:最大相对偏差从15%降至4.8%。车载外场实验表明:修正因子在0.8～1之间。上述结果验证了算法在尾气CO、CO2浓度修正中的有效性。开展了检测系统的外场应用实验,分别对轻型汽油车和柴油车CO、CO2排放因子进行了测量,并与美国Sensors公司的SEMTECH-CO/CO2检测仪进行了对比,实验结果表明:CO排放因子相关度达到0.931,CO2排放因子相关度达到0.925。更多还原

【Abstract】 CO and CO2 emissions from the vehicle exhaust are one of the major mobile sources of the urban air pollution.At present,the state has issued relevant policies and regulations to strengthen the supervision of the exhaust CO and CO2 emissions.Vehicle-mounted equipment that detects CO and CO2 emission factors in China mainly depends on imports.In this paper,the key technologies for the detection system of the CO and CO2 emission factors of the vehicle exhaust has been researched to provide the technical support for the localization testing equipment for the CO and CO2 emission factors.Aimed at the sampling and pretreatment demand for the vehicle exhaust of high temperature,the key components such as the portable small cyclone separator for water-removal,the improved pitot tube for the tail pressure differential measurement,the multi-point temperature measuring module,and the improved orifice plate for the sample gas pressure measuring have all been developed.Then the gas sampling and pretreatment circuit has been designed and the pretreatment system for the high-temperature has been integrated and the purpose of removing particulate matter and moisture from the exhaust has been achieved.The corresponding parameters such as the temperature and mass flow of the CO and CO2 emission factors have been obtained from the vehicle exhaust of high temperature.The experimental results show that after the pretreatment relative humidity of the sample gas is less than 40%,its temperature is less than 50℃,its particle diameter is less than 3 μm,also with a very low content,all of which can meet the requirements of the optical detection and analysis module.The gas circuit switching and driving module for the zero,scalar and sample gas of the detection system was designed.The detection circuit to detect temperature,humidity,and pressure parameters of sample gas were developed.In the infrared absorption signal detection circuit,an adaptive wide-range signal detection circuit and a single-frequency filter circuit based on DSP and a modified dual-sampling circuit for modulating the photoelectric signal were developed.Fast,wide-range,low-noise detection of the infrared measurement signals is achieved.The comparison experiments show that the response time of the high-temperature exhaust CO and CO2 concentration detection system is 0.5s,a six-fold increase in response speed over traditional methods.The effect of temperature,humidity,and pressure on the concentration of CO and CO2 measured after pre-treatment was analyzed,an on-line correction algorithm for CO and CO2 concentration detection based on neural networks has been proposed,the inversion accuracy of CO and C02 concentrations in high temperature tail gas is improved.Standard sample experiments show that the maximum relative deviation has decreased from 22%to 5.8%.Simulation comparison experiments show that the maximum relative deviation has decreased from 15%to 4.8%.Vehicle experiments show that the correction factor is between 0.8 and 1.The above results verify the effectiveness of the algorithm in the CO and CO2 concentration correction.The external field application experiment of the detection system has been carried out.The CO and CO2 emission factors of the light gasoline vehicle and the diesel one have been measured respectively.And compared with the SEMTECH-CO/CO2 detector of Sensors,the experimental results showed that the correlation degree of the CO emission factor has reached 0.931,while that of the CO2 emission factor has reached 0.925.更多还原