一种气溶胶测量仪器标定系统的设计及性能评估

Development and Performance Evaluation of a Supermicron Particle Generation System for Aerosol Instrument Calibration

对气溶胶测量仪器进行准确标定是保证大气环境及污染源颗粒物测量数据质量的重要前提.本研究搭建了一套多分散在线标定气溶胶测量仪器的系统,该系统采用超声气溶胶发生装置产生多分散颗粒物,并用空气动力学粒径谱仪对颗粒物粒径分布进行测量.评测结果表明该系统干燥腔室内气溶胶稳定、均匀,且符合对数正态分布.以采样器为例,已有研究多使用单分散离线标定方法对采样器切割性能进行标定,该方法操作繁琐、实验周期长.利用多分散在线标定系统对PM_(2.5)和PM_(10)双级虚拟撞击采样器进行标定,并与单分散离线标定方法进行了对比,两套系统的标定结果呈现较好的一致性,但多分散在线方法大大缩短了标定实验周期.

Accurate calibration of aerosol measurement instruments is critical for ensuring the data quality when sampling ambient particulate matter（ PM） or those from emission sources. A system for calibrating these instruments was set up,which included an ultrasonic device to generate polydisperse supermicron particles,a chamber,and an aerodynamic particle spectrometer to measure particle size distribution. We verified its performance in stably generated testing aerosol with good spatial uniformity,controlled size distributions and concentrations. The testing aerosol generated had a lognormal distribution. A PM_（10） and PM_（2.5）two-stage virtual impactor was calibrated using this online method. Collection efficiencies of PM_（10） and PM_（2.5）stages calibrated by an off-line method using monodisperse particles were also used for comparison. The results from two different methods were consistent with each other. Though the off-line method has been widely used to calibrate PM samplers,it suffers from long experimental duration（ 2-3 days for calibrating one sampler）. In contrast,the online method allows for a rapid calibration（ less than half a day for calibrating one sampler）.