Homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC) in compression ignition engine with low octane gasoline

• Published in: Energy (Oxford) Vol. 158; pp. 181 - 191
• Main Authors: An, Yanzhao, Jaasim, Mohammed, Raman, Vallinayagam, Hernández Pérez, Francisco E., Sim, Jaeheon, Chang, Junseok, Im, Hong G., Johansson, Bengt
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2018; Elsevier BV
• Subjects: Chemical kinetics; Combustion; Combustion temperature; Compression; Cylinders; Engines; Evolution; Flame index; Flame retardants; Fluidized bed combustion; Gasoline; HCCI; High temperature; Ignition; Injection; Kinetics; Low octane gasoline; Low temperature; Octane; Organic chemistry; Piston rings; PPC; Premixed combustion; Premixed flames; Reaction kinetics; Soot; Spatial distribution; Temperature effects; HCCI; PPC; Low octane gasoline; Flame index; Premixed combustion
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2018.06.057

The present study investigated the in-cylinder combustion for low octane 70 primary reference fuel (PRF70) by the method of the flame index during the transition from homogeneous charge compression ignition (HCCI) combustion to partially premixed combustion (PPC). Full cycle engine simulations were performed using CONVERGE™, coupled with chemical kinetics. Good agreements between the simulations and experiments were achieved at HCCI and PPC combustion modes. The fully premixed HCCI mode was achieved at the earliest injection timing of −180 CAD aTDC with the combustion temperature below 1600 K, where the formation of soot and NOx can be successfully avoided. For the injection timing of −100 CAD aTDC, the premixed charge compression ignition (PCCI) was achieved where the premixed combustion clouds were mainly distributed in the piston top-land zone and were surrounded by the diffused combustion that occurs in the piston bowl and the periphery of piston top. Less premixed flames were formed in piston top and surrounded by more diffusion mixtures at PPC mode. The in-cylinder HO2 evolution profile displayed two bumps which were distributed in low temperature zone and high temperature zone respectively. The spatial and temporal evolution of HO2 is very similar to the distribution of premixed flames. •The method of flame index is applied in engines at low temperature combustion modes.•Experimental combustion images show homogenous and stratified combustion at HCCI and PPC modes.•Computational fluid dynamics with chemical kinetics is used to simulate combustion and emission.•Premixed flame ratio is higher at HCCI and PPCI mode when compared to PPC mode.•The evolution of HO2 species during combustion is similar to flame index distribution.