A Dynamic Aerosol Generation System for Aerosol Sensor Calibration

摘要

Airborne particles in the ambient are often time-varied in concentration and size. It is because of either the time-variation or moving of particle sources. Existed aerosol generators or techniques are however designed to produce stable aerosol in constant concentration. In our effort of developing personal aerosol sensors it becomes desired to evaluate the performance of aerosol sensors under the challenge of time-varying aerosol in the laboratory setting. A new dynamic polydisperse aerosol generation system, enabling the programmable variation of test aerosol concentration, is thus developed. The dynamic aerosol generation system consists of a custom-made Collison atomizer and dynamic aerosol dilution chamber. The atomizer generates polydisperse aerosols in fixed concentration and size distribution. Produced aerosol is then diluted in the mixing chamber by clean air while keeping the same particle size distribution as original. A mass flow controller is used to program the time-variation of dilution flow into the mixing chamber. A computer program is designed to control the system setting time, time-varying dilution flowrate ratio, and to establish the stepping/continuous mode of dilution process. In this study the performance of the above-described dynamic aerosol system is evaluated by a condensation particles counter (CPC) for total number concentration, quartz crystal microbalance (QCM) for total mass concentration and Fast Mobility Particle Sizer (FMPS) for size distribution measurement. We will present the detail of system setup and evaluation result in this talk.