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. Program summaryProgram title: CoFlameCatalogue identifier: AFAU_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AFAU_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: GNU General Public License, version 3No. of lines in distributed program, including test data, etc.: 94964No. of bytes in distributed program, including test data, etc.: 6242986Distribution format: tar.gzProgramming language: Fortran 90, MPI. (Requires an Intel compiler).Computer: Workstations.Operating system: Linux.RAM: From 16 GB to over 1000 GB depending on size of system being simulatedClassification: 22.Nature of problem:Soot formation in laminar diffusion flames with detailed description of thermodynamics, kinetic, and transport dataSolution method:Finite volume method utilizing the pseudo-transient SIMPLE algorithm and locally coupled chemistry solverAdditional comments:The code was specifically developed for modeling soot formation in laminar diffusion flamesRunning time:From hours to a month depending on the complexity of the chemical mechanism and the disparity between the initial guess and the final solution.