Error propagation in data inversion of electrical low pressure impactor

Abstract

The data inversion algorithm of the Dekati electrical low pressure impactor (ELPI+) is the procedure to convert the electrical currents measured in each impactor stage into a particle size distribution. If a particle is collected in the incorrect stage, either due to particle bounce or premature collection, the erroneously induced current will cause an error to propagate through the data inversion. In this work, it is examined how this error propagation will modify the particle number size distribution. It is shown that particle bounce can contribute considerably to an erroneous particle distribution as one large bouncing particle can be misinterpreted as more than 10,000 small particles. This indicates that efforts should be made to avoid particle bounce in the ELPI+ as particle bounce thoroughly modifies the obtained particle number size distribution. On the other hand, it appears that the ELPI+ is quite robust against the effects of premature particle collection.

Copyright © 2022 American Association for Aerosol Research

Graphical abstract

Editor:

• Kihong Park

Acknowledgments

The authors gratefully acknowledge Dekati Ltd. for providing a description of the data inversion implementation in the ELPI+ firmware.