Method for obtaining aerosol particle size distributions

Patent metadata

Field	Value
Publication number	US-9638665-B2
Application number	US-201414898934-A
Country	US
Kind code	B2
Filing date	Jun 17, 2014
Priority date	Jun 17, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

The invention provides a method for obtaining aerosol particle size distributions with a scanning mobility particle sizer (SMPS) device comprising a differential mobility analyzer (DMA); which method comprises the stages:
(i) collecting a first data set of particle concentrations vs. size for a size range from a predetermined minimal size D min to an intermediate size D t by varying a voltage applied to a DMA column of an SMPS from V min to V t1 at a first sheath flow rate Q sh1 ; (ii) changing the sheath flow rate from the first sheath flow rate Q sh1 to a second sheath flow rate Q sh2 ; (iii) collecting a second data set of particle concentrations vs. size for a size range from the intermediate size D t to a predetermined maximum size D max by varying the voltage applied to the DMA column of the SMPS from V t2 to V max at the second sheath flow rate Q sh2 ; (iv) convolving the first data set from stage (i) using an apparatus function of the DMA and the sheath flow rates Q sh1 and Q sh2 in stage (ii); (v) combining the convolved data set from stage (iv) with the second data set from stage (iii) to form a merged data set corresponding to the size distribution from D min to D max ; and (vi) deconvolving the merged data set to provide a size distribution for the full size range D min to D max .

Also provided are a DMA, SMPS or Fast Mobility Particle Sizer (FMPS) apparatus set up to perform the method.

First claim

The invention claimed is:

1. A method for obtaining aerosol particle size distributions with a scanning mobility particle sizer (SMPS) device comprising a differential mobility analyzer (DMA); which method comprises the stages:
(i) collecting a first data set of particle concentrations vs. size for a size range from a predetermined minimal size D min to an intermediate size D t by varying a voltage applied to a DMA column of an SMPS from V min to V t1 at a first sheath flow rate Q sh1 ;
(ii) changing the sheath flow rate from the first sheath flow rate Q sh1 to a second sheath flow rate Q sh2 ;
(iii) collecting a second data set of particle concentrations vs. size for a size range from the intermediate size D t to a predetermined maximum size D max by varying the voltage applied to the DMA column of the SMPS from V t2 to V max at the second sheath flow rate Q sh2 ;
(iv) convolving the first data set from stage (i) using an apparatus function of the DMA and the sheath flow rates Q sh1 and Q sh2 in stage (ii);
(v) combining the convolved data set from stage (iv) with the second data set from stage (iii) to form a merged data set corresponding to the size distribution from D min to D max ; and
(vi) deconvolving the merged data set to provide a size distribution for the full size range D min to D max .

2. A method according to claim 1 wherein the first sheath flow rate Q sh1 is higher than the second sheath flow rate Q sh2 .

3. A method according to claim 1 wherein the SMPS is set up to measure particle size distributions from 3 nm to 4,000 nm.

4. A method according to claim 1 wherein the SMPS is set up to measure particle size distributions from 5 nm to 1,000 nm.

5. A DMA and/or SMPS apparatus set up to perform the method of claim 1 .

6. A Fast Mobility Particle Sizer (FMPS) apparatus set up to perform the method of claim 1 .

7. A method according to claim 2 wherein the SMPS is set up to measure particle size distributions from 3 nm to 4,000 nm.

8. A method according to claim 2 wherein the SMPS is set up to measure particle size distributions from 5 nm to 1,000 nm.

Assignees

• Particle Measuring Syst

Inventors

• Gorbunov Boris Zachar

Classifications

• G01N15/0266

  with electrical classification · CPC title

• G01N27/622 Primary

  Ion mobility spectrometry · CPC title

• G01N2015/1087

  Physics · mapped topic

• G01N15/10

  Investigating individual particles · CPC title

• G01N27/62 Primary

  by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode · CPC title