An Alternative Technique for Low Particulate Measurement 2001-01-0218
For the purposes of environmental protection, regulations of particulate matter are becoming more stringent year by year. Accordingly, engine systems have been improved and particulate emissions are much lower compared to those of previous engine systems.
The automotive industry generally uses a gravimetric method to quantify particulate emissions. It is becoming increasingly difficult to quantify particulate emissions using a conventional gravimetric balance because the amount of particulates continues to decline.
In order to overcome this problem, a new method has been developed that uses gas analyzers to measure potentially as much as several micrograms of particulates. Furthermore, with this method, it is possible to simultaneously analyze volatile organic fraction (VOF), soot, and sulfates.
The particles collected by a quartz filter are placed in a furnace at a specific temperature, and VOF and sulfates are vaporized in an inert atmosphere. The organic fraction is oxidized and measured by a gas analyzer as CO2. Vaporized sulfate is converted to SO2 under high temperature and measured by a gas analyzer. These gas concentrations are then used to determine the VOF and sulfate mass. Subsequently, O2 is fed into the furnace, the soot is oxidized, and the CO2 concentration is measured to determine soot mass.
This paper investigates the performance of this new method of using a gas analyzer and discusses the experimental results.