A widely used instrument capable of detecting and measuring
PM is an electrical PM detector. A typical PM detector consists of an
aerosol charger, an ion collector, and an aerosol electrometer. In the
PM detector, aerosols are directed into the aerosol charger to charge
the aerosol particles by ion-particle collisions via the diffusion
charging andfield charging mechanisms. The charged aerosol then
passes through an ion collector to remove excess ions and moves on
to a highly sensitive aerosol electrometer for charge measurement
[2,3]. Generally, an ion collector is one of the most important parts
of the electrical PM detector because it can prevent contamination
of the signal current to be measured by free ions potentially
reaching the electrometer[4]. The ion collector typically uses the
principle of electrostatic precipitation and has a geometrical
configuration similar to the coaxial cylindrical electrostatic pre-cipitator. It consists of an inner electrode placed along the axis of an
outer electrode. For generating an electrostaticfield inside the * Corresponding author.
E-mail address:panich_intra@yahoo.com(P. Intra).
Contents lists available atScienceDirect
Journal of Electrostatics
journal homepage: www.elsevier.com/locate/elstat
http://dx.doi.org/10.1016/j.elstat.2014.09.001
0304-3886/©2014 Elsevier B.V. All rights reserved.
Journal of Electrostatics 72 (2014) 477e486
collector a DC voltage is applied to the inner electrode, while the
outer electrode is grounded. When ions are introduced into the
collector, the electrostatic force drives them toward the outer
electrode where they deposit on the inner surface of the electrode.
The design and performance evaluation of the ion collector has
received little attention in the literature [5e12]. Higher applied
voltages (10e150 V) andflow rates (5e15 L/min) were theoretically
and experimentally studied by numerous works[5e7,12]. However,
a mini-volume electrical PM detector commonly has been operated
at volumetric aerosolflow rates lower than 5 L/min and therefore
needed a compactable system for afield test and measurement.
Therefore, an ion electrostatic collector needs to be designed and
numerically and experimentally evaluated for the efficiency of
collecting both negative and positive ions at ionflow rates smaller
than 5 L/min and collection voltages lower than 50 V. The geom-etry, dimension and size of the ion collector would have influenced
to the complexity and expense of the ion collector and then to keep
it cost effective.