Experimental and Numerical Investigation of a Particle Filter Technology for NG Heavy-Duty Engines

The forthcoming introduction of the EURO VII regulation requires urgent strategies and solutions for the reduction of sub-23 nm particle emissions. Although they have been historically considered as particulate matter-free, the high interest for Natural Gas (NG) Heavy-Duty engines in the transport sector, demands their compliance with the new proposed regulations. In order to obtain high conversion of gas pollutants and a strong abatement of the emitted particles, the use of Particle Filters in NG aftertreatment (CPF) in conjunction with the Three-Way Catalyst (TWC) may represent an attractive and feasible solution. Performances of a cordierite filter were explored through an extensive experimental campaign both in Steady-State conditions and during transient engine maneuvers that involved a whole analysis of the emitted particles in terms of number and mass. This investigation assessed different emitted particle reduction efficiency, highlighting distinct levels between no-load (low idle phases) and load operating conditions. The analysis was supported by the development of a specific 1D filtration model to evaluate the particles abatement. This model was also validated during a World Harmonized Transient Cycle (WHTC), proving to be a valuable tool for understanding filtration phenomena during critical phases of the cycle. The tested filter technology showed high filtration efficiency with global levels approaching 90% over the whole cycle, without significant increase in backpressures and fuel consumption. The performed analysis lays the foundation for the use of innovative and simplified filtration models to support the optimization process of this device in view of the next stringent regulations.