Molecular dynamics simulation investigation of fuel droplet in evolving ambient conditions I. Stankovic Scientific Computing Laboratory, Institute of Physics Belgrade, University of Belgrade, 11080 Zemun, Serbia COST Workshop of Flowing Matter Action: WG4 Application, Dissemination and Outreach Sofia, Bulgaria, 27-28 April 2015 1/21
12 senior researchers (7 hold PhD from abroad) 15 PhD students 3national projects, 2 Horizon 2020 projects, 2bilateral projects, 4 COST projects The computing resources of the PARADOX 1000CPU cores and 50 TB of storage & 106 working nodes with 1696 processors with communication speed of 40 Gbps(2013 upgrade)
(1) nanowire networks, carbon nanotube transistors Conduction only through semi-conductive CNTs! How large is conductivity? source drain dielectric gate (2) assembly of magnetic particles (3) nano & molecular friction
overview principal processes taking place in cylinder non-equilibrium molecular dynamics simulations (NEMD) chemical reactions & NEMD d NEMD simulations of droplet in evolving environment Hiromichi Yanagihara Research & Development, Toyota Motor Europe, Belgium Fredrik Blomgren Chalmers Industrial Technologies, Göteborg, Sweden general overview res search done 3/21
time& length scale of combustion 2000rpm > 30ms (one stroke = compression+expansion) cylinder size ~0.05m, spray size ~0.01m, droplet size ~10-6 piston speed is ~3m/s transport processes in gas phase: - diffusion (~2 10-5 m 2 /s, in 5ms diffusion distance ~10-4 m) - turbulence (quite fast) number of cycles per car/hour 10 5 or globally per day ~10 12 4/21
experiment: glass cylinder H. Yanagihara in Thermo-and Fluid Dynamic Processes in Diesel Engines 2, Ed. J.H. Whitelaw, F. Payri, C. Arcoumanis 5/21
3 elements needed for combustion: 1. fuel 2. oxygen 3. heat Damköhlernumber reaction rate Da= reactant mass transfer 6/21
chemistry Da= reaction rate reactant mass transfer 7/21
chemistry: auto-ignition/extinction 8/21
state-of-art Is this direction? chemistry source: Wikipedia 9/21
10/21
molecular dynamics initial configuration H. Yanagihara, I.S., et al, Combustion and Flame (2013) 11/21
We did a little bit QM... reaction barrier in liquid/gas phase are comparable H. Yanagihara, I.S., et al, Combustion and Flame (2013) 12/21
molecular dynamics & chemistry We wanted to obtain insight into - oxygen adsorption & absorption, - influence of increasing pressure & temperature, -behaviour of oxidation products in liquid phase, and - diffusion of oxygen. 13/21
molecular dynamics & chemistry Combustion includes >10 2 reactions -we introduce one model reaction which creates aldehyde & alcohol. 14/21
system evolution up to boiling point 6000 iso-octane (C 8 H 18 ) molecules and 10 5 air molecules (79% nitrogen and 21% oxygen molecules) H. Yanagihara, I.S., et al, Combustion and Flame (2013) 15/21
system evolution absorption & chemical reactions 16/21
diffusion rate in fuel vs. temperature 17/21
time evolution iso-octane boiling point 450K 298K (1bar) 356K (1.9bar) 426K (3.5bar) 326K (1.4bar) 389K (2.6bar) 465K (4.8bar) 18/21
reaction position & product behaviour 298K (1bar) 326K (1.4bar) 356K (1.9bar) 389K (2.6bar) 426K (3.5bar) 465K (4.8bar) 19/21
pressure influence 20/21
pressure influence 21/21
molecular combustion scheme which utilizes molecular scale processes injection point is selected at sufficiently high pressure and low temperature evaporation rate is moderate and oxygen is comeing into the fuel droplets oxygen is stored in the molecular form of and its products stored oxygen (in aldehydesand alcohols) help combustion creating time resolved energy release.
Thank you!