AEROSOL PARTICLE GRADING PROCESS

摘要

Aerosols play an essential role in the atmosphere and in technical processes. It is often desirable to extract particles having a determined variable size from an aerosol. This is the object of the disclosed process. For that purpose, the aerosol flows first through a corona charger that imparts an electric charge to the particles depending on an adjustable charging parameter. The aerosol then flows through a mobility sorter that extracts particles with a determined electric mobility Z depending on a deflection voltage. Since Z is the product of a particle size-dependent parameter b and particle charge q, this mobility grading is equivalent to a size grading when particles having a determined size substantially have a determined charge. The corona charger approximately satisfies this condition when the charging parameter is set according to the desired size of the particles to be extracted. In the disclosed process, a control circuit sets the charging parameter and the deflection voltage so that the particles that leave the sorter have a variable size as predetermined in the control circuit.