On acoustic performance of the particle oxidation catalyst POC (R)

Environmental legislation must be considered when designing internal combustion engine (IC-engine) exhaust systems. The reduction of the exhaust noise is mainly managed by proper silencer design, while less attention is paid to the acoustic performance of the after treatment devices (ATD). Usually the ATD unit is designed with the main emphasis on the emission control, i.e., chemical efficiency. It is known from the earlier studies, that the transmission loss of a typical car ATD unit can be quite significant. A car ATD unit is classically assembled from several specific parts such as selective catalytic reducers (SCR), diesel oxidation catalysts (DOC) and diesel particulate filters (DPF). One new alternative to the conventional DPF is the particle oxidation catalyst (POCr). The substrate used in the the POC-X type filter consists of fine, corrugated metallic mesh screens piled askew and rolled into a cylindrical shape. This paper presents a first investigation of the acoustic performance of the POC-X. In addition to the experimental studies, methods to define the acoustic two-port simulation model for POC-X are discussed. For comparison, also the acoustic behaviour of conventional open foil coated (OFC)-type catalysts are studied