Simulating combustion in a PCI (premixed compression ignition) engine using DI-SRM and 3 components surrogate model

Abstract A detailed chemistry and pollutant formation model combined with an advanced combustion simulation tool DI-SRM (direct injection stochastic reactor model) and time based mixing model are used to simulate the in-cylinder physico-chemical processes such as compression, heat transfer, charge stratification/mixing and gas phase chemistry in a single cylinder diesel engine run in premixed compression ignition (PCI) mode. These models were used to simulate the combustion of different model fuels (n-heptane, PRF 84 and TRF 82, a toluene isooctane and n-heptane blend) and full boiling range unleaded gasoline (ULG 84 and ULG 91), using the same 3 components (n-heptane, iso-octane and toluene) surrogate model for all five fuels. Soot was simulated using the method of moments, a Probability Density Function (PDF) based model and the other pollutants such as NOx, CO and unburned hydrocarbon (UHC) are estimated through the chemical mechanism model used in this study. The blending of each surrogate fuel was based on the auto-ignition characteristics of the fuel used in the experimental work. The model performed well, in terms of in-cylinder pressure, heat release rate, combustion phasing parameters and pollutant emissions. Phi-T maps were used to gain further insight into both the simulated and experimental data. These maps are used to better understand the processes that take place during the combustion event under PCI combustion mode such as mixing, fuel auto-ignition characteristics and the effect of RON and aromatic content on PM emissions.