Modeling HCCI Engine Combustion Coupling Cantera to KIVA 4 2015-01-0816
A constant volume, zero-dimensional reactor for ideal gas mixtures (CVR) was implemented using Cantera within KIVA-4 in order to simulate a homogeneous charge compression ignition engine (HCCI). Only partial densities are exchanged between KIVA and Cantera. An initial partial density is calculated by KIVA for Cantera. New densities are generated by Cantera using the CVR and are given back to KIVA. Finally, the calculations are completed by KIVA in the main iteration scheme. No further modifications for constitutive equations or models were made for KIVA-4 or Cantera.
In order to maintain the constant volume assumption in each cell and solve the CVR, a double adaptive time step is used within the computational fluid dynamics (CFD) code. The time scheme solves a large time step for the CFD and a comparatively small time step for the kinetic reactions. For the fluid phase, time step is increased if there is a low heat release in all cells. Additionally the time step is decreased if there is a significant heat release in any cell. The fluid timestep accounts for Cantera's integration time. If the fluid timestep is decreased, the main iteration is repeated with a new integration time for Cantera.
The simulations agree well with secondary experimental data. Two mechanisms have been used to obtain results. Good estimates have been obtained for heat release and pressure. Hydrocarbons and carbon monoxide formations have been under predicted. Nitrous oxides formation has been over predicted. Peak temperature has been in accordance with previous authors.