Thermal Conditioning of Exhaust Gas: Potential for Stabilizing Diesel Nano-Particles

Conditioning of diluted exhaust gas by Thermo-Conditioner prior to measurement has been proposed by the GRPE/PMP Research Council of the United Nation in order to achieve stability in nano-particle measurement. In this study the effect of thermo-conditioner on the thermo-physical behavior of nano-particle under different conditions have been clarified. Stability in measurement was also attempted depending on the characteristics of nano-particles. Quality of the raw exhaust gas, the dilution ratio and temperature, and the thermal conditioning temperature were considered as the main parameters. Exhaust gas from a medium duty DI diesel engine was used for analysis. Scanning Mobility Particle Sizer was used for measuring the concentration of nano-particles.

It was concluded that the concentration of nuclei-mode particles within the size range of 15∼30 nm are significantly influenced by the thermal conditioning temperature. However the concentration of accumulation mode particles having the diameter of about 100 nm experience no influence. Thermal conditioning of exhaust gas at a temperature of over 300°C is assumed to be sufficient for stabilizing the nano-particles. Hot dilution showed better stability in measurement than cold dilution.