Numerical Assessment of Flow Pulsation Effects on Reactant Conversion in Automotive Monolithic Reactors
Artikel i vetenskaplig tidskrift, 2022

Highly transient engine-out emissions imply significant challenges for the optimization and control of automotive aftertreatment systems, motivating studies of the effects of flow pulsations on the system behavior. In this work, an axisymmetric aftertreatment system with a first-order reaction in the monolith section is chosen to demonstrate the role of pulsations on the time-averaged conversion at the exit. Reactive computational fluid dynamics simulations under transient conditions are performed by applying the SST k-ω turbulence model along with a reactant species balance equation and a porous medium description of the catalyst. Four different types of temporal velocity variations (constant, step-like, sawtooth and sinusoidal) are applied at the inlet. Additionally, the corresponding fluctuations driven by a prescribed inlet pressure are also investigated. It was found that the fluctuations in the incoming flow affect the transient response of the monolith, the time-averaged conversion, the evolution of the flow uniformity index and the dispersion downstream of the catalyst. It is also shown that the retention time distribution is modulated by the pulsations and that the mixed-cup conversion span is different for geometrically identical systems having the same velocity span if the fluctuation characteristics are different. In conclusion, simulations of phenomena that depend on time-resolved boundary conditions from experiments require proper characterization of fluctuations present in the real-world systems; otherwise, the method of recreating the signal at the boundary may influence the obtained results.

reactive flow

inlet boundary condition

flow pulsations

uniformity

Computational Fluid Dynamics

Författare

Pratheeba Chanda Nagarajan

Chalmers, Mekanik och maritima vetenskaper, Förbränning och framdrivningssystem

Henrik Ström

Chalmers, Mekanik och maritima vetenskaper, Strömningslära

Jonas Sjöblom

Chalmers, Mekanik och maritima vetenskaper, Förbränning och framdrivningssystem

Catalysts

20734344 (eISSN)

Vol. 12 6

Modellering av avgasefterbehandlingssystem för noll-utsläpp

Kompetenscentrum i förbränningsmotorteknik, 2019-06-03 -- 2024-01-31.

Ämneskategorier

Annan maskinteknik

Annan kemiteknik

Styrkeområden

Transport

Energi

DOI

10.3390/catal12060613

Mer information

Senast uppdaterat

2022-08-01