Particle Sizer for Measurement of Engine Emissions

Current instruments for monitoring particulate matter (PM) are inadequate in their ability to determine aerosol size or size distributions. Operation of existing systems requires a good understanding of sensor design. For example, variations in ambient conditions may necessitate either new calibration or measurements to be computationally corrected to ensure accurate particle size determination. This required level of expertise limits wide deployment of existing systems. As a result, NAL Research Corporation proposes the development of a portable real-time aerosol-sizer based on a pair of miniature laser-Doppler velocimeters (LDVs) designed with diode lasers and avalanche photodiodes. Particle aerodynamic diameter can be directly obtained from the measured velocity gradient. The use of miniature LDVs enables the proposed instrument to be simple, compact and lightweight. Furthermore, the sensor will not need calibration contrary to the time-of-flight (TOF) aerodynamic particle sizer (APS). Minimal technical competence will be expected for operation in a wide variety of conditions for emissions characterization and monitoring. These factors combine to ensure the system is inexpensive.