Encyclopedia of Environmental Science and Engineering, Volume I and II

AEROSOLS 27

SCREEN

UNIPOLAR

IONS

DC H.V.

AEROSOL AEROSOL

RADIOACTIVE SOURCE

BIPOLAR IONS

DC H.V.

Q

c

Q

a

AEROSOLCLEAN AIR

DC H.V.

Q

c

Q

a

AEROSOLCLEAN AIR

r 1

r 2

L

EXHAUST, Qc

TO DETECTOR

UNCHARGED PARTICLE

TO DETECTOR

Qa + Qc

AEROSOL

CNC

ELECTROMETER

FILTER

AEROSOL

a) Corona discharge (unipolar ions) b) Radioactive source (bipolar ions)

(a) Charging section for particles

a) Integration type b) Differential type

(b) Main section

a) Electrometer b) CNC or Electrometer

(c) Detection of charged particles

ELECTRICAL CURRENTor PARTICLE NUMBERAPPLIED VOLTAGE ELECTRICAL CURRENTor PARTICLE NUMBERAPPLIED VOLTAGE

a) Integration type b) Differential type

(d) Response curve

L

FIGURE 11 Two types of electrical mobility analyzers for determining aerosol size. Charging,

classification, detection and response are shown for both types of analyzers.

C001_002_r03.indd 27C001_002_r03.indd 27 11/18/2005 10:09:14 AM11/18/2005 10:09:14 AM