A study on the filtration efficiency and regeneration capacity of the gasoline particulate filter

Abstract

Gasoline particulate filters (GPF) are becoming a standard technology in gasoline engines because of the need for compliance with particulate matter (PM) emissions requirement. Generally, GPFs can be placed after a three-way catalysts (TWC) in the same can, or in a separate can downstream. As typical wall-flow filters, particulate matter is removed from the exhaust by physical filtration using a honeycomb structure similar to an emissions catalyst substrate but with the channels blocked at alternate ends. The goal of work was to the study the filtration efficiency and regeneration capacity of the GPF. Laboratory emission tests were carried out for one 2.0L gasoline turbo direct injection (GTDI) prototype vehicle according to the new World Harmonized Light Vehicle Test Cycle (WLTC). The data showed that the vehicle has a reliable and high GPF filtration efficiency to intercept the particulate pollution from the exhaust. Meanwhile, five 2.0L GTDI prototype cars from respective China stage 6 platforms were used for further study of soot accumulation and regeneration capacity. The results, in terms of modeled emissions in tests under real driving conditions of China cities (Nanjing and Hainan), showed that the heavy traffic road conditions lead to a low probability of soot regeneration. However, the GPF regeneration capacity of the test convoy was still adequate. In addition, the drive cycle exhibiting good road conditions with more aggressive driving behaviors offered a better regeneration environment due to the elevated GPF temperature and more frequent occurrence of deceleration fuel shut off (DFSO) creating an environment of excess oxygen content.