CoFlame: A refined and validated numerical algorithm for modeling sooting laminar coflow diffusion flames

Abstract

Mitigation of soot emissions from combustion devices is a global concern. For example, recent EURO 6 regulations for vehicles have placed stringent limits on soot emissions. In order to allow design engineers to achieve the goal of reduced soot emissions, they must have the tools to so. Due to the complex nature of soot formation, which includes growth and oxidation, detailed numerical models are required to gain fundamental insights into the mechanisms of soot formation. A detailed description of the CoFlame FORTRAN code which models sooting laminar coflow diffusion flames is given. The code solves axial and radial velocity, temperature, species conservation, and soot aggregate and primary particle number density equations. The sectional particle dynamics model includes nucleation, PAH condensation and HACA surface growth, surface oxidation, coagulation, fragmentation, particle diffusion, and thermophoresis. The code utilizes a distributed memory parallelization scheme with strip-domain decomposition. The public release of the CoFlame code, which has been refined in terms of coding structure, to the research community accompanies this paper. CoFlame is validated against experimental data for reattachment length in an axi-symmetric pipe with a sudden expansion, and ethylene-air and methane-air diffusion flames for multiple soot morphological parameters and gas-phase species. Finally, the parallel performance and computational costs of the code is investigated.

A novel soot concentration field estimator applied to sooting ethylene/air laminar flames

“…The soot estimator consists of a library of a series of numerical solutions of well validated sooting flames. Sectional detailed soot modeling are employed as well as a detailed kinetic mechanism to predict PAHs, which are the gas species responsible for the nucleation of the soot particles (Eaves et al, 2012(Eaves et al, , 2016Saffaripour, Kholghy, Dworkin, & Thomson, 2013;Veshkini et al, 2014;Zhang, Thomson, Guo, Liu, & Smallwood, 2009). From these numerical solutions the Lagrangian histories of soot-containing fluid parcels are algorithmically gathered and stored in a library.…”

Model Guided Application for Investigating Particle Number (PN) Emissions in GDI Spark Ignition Engines

“…where m is the particle's mass, np is the number of primaries in the particle, and YSOF is the mass fraction of SOF compounds in the particle. With this type space, an approximation of the fractal aggregate nature of soot particles can be retrieved [40]. Note that in this model, all primaries within a given particle are assumed to be of equal size.…”

“…The processes governing formation and growth of particles in the population balance model include inception, surface growth and oxidation, aggregation (coagulation), and breakage (fragmentation). The PBM is solved via a sectional method [40,42,43].…”

Modelagem Computacional De Chamas Laminares Não Pré-Misturadas Com Mecanismo De Cinética Química Detalhada, Utilizando Openfoam

“…Com o intuito de estudar a redução da emissão de fuligem nos processos de combustão devido aos danos à saúde e ao meio ambiente, Eaves et al [5] apresentam um estudo dos mecanismos de formação de fuligem, incluindo crescimento e oxidação, que possibilite a determinação de métodos economicamente viáveis de reduzir essas emissões. Para isso, modelos numéricos complexos são usados para se alcançar maior entendimento dos fatores que afetam o mecanismo de formação de fuligem.…”

“…O código desenvolve soluções para velocidade radial e axial, temperatura, conservação de espécies, e agregados de fuligem e equações de densidade de número de partículas primárias. O modelo de dinâmica de partículas seccionais inclui nucleação, condensação de PAH e crescimento superficial de HACA, oxidação de superfície, fragmentação, coagulação, difusão de partículas e termoforese [5]. Para validar o código modelado, os resultados obtidos foram comparados com dados experimentais.…”