Comparison of combustion particle number concentration and size

Project Description

The particle number concentration and size distribution in a neutral combustion aerosol are measured with two types of instruments: 1st, the number concentration is measured with a particle counter that does not evaluate the particle size (e.g. CPC = condensation particle counter, OPC = optical particle counter). 2nd, the particle size distribution is measured through the combination of a particle size classifier with a particle counter (e.g. SMPS = scanning mobility particle sizer).

The particle size distribution can be analyzed for the particle number concentration and the geometric mean. But this analysis depends on instrumental parameters as well as on an unknown algorithm implemented in the manufacturer's software. Thus, the separation of the particle size distribution and the particle number concentration comparison will allow the participants to directly compare their particle counters.

An in-house generated combustion aerosol in the size range 50 to 170 Nanometre (nm) and the number concentration range 10,000 to 1,000,000 particles per Millilitre (mL^-1) will be used for the comparison. Results of the comparison will be the following:

• Average particle number concentration at several points between 10⁴ and 10⁶ mL^-1. The results will be referred to standard conditions (0 °C and 1013.25 hPa). A typical measurement will last 15 minutes.
•  Average particle size at several points between 50 nm and 170 nm. The size is defined as the geometric mean (or mode) of the size distribution and corresponds to the diameter of a sphere having the equal electrical mobility diameter (equivalent mobility diameter). A typical measurement will last 30 minutes.
• The degree of equivalence will be plotted for the up mentioned quantities.

Anticipated date for the comparison will be in the last quarter of 2008. The comparison will take place at the Federal Office of Metrology METAS in Bern, Switzerland.

This comparison is a follow-up of the EURAMET Project Metrology infrastructure for airborne nanoparticles.

Final Report 2009-09-22

The project has been completed and the report can be downloaded here>>.