Numerical simulation of syngas combustion with a multi-spark ignition system in a diesel engine adapted to work at the Otto cycle

摘要

This work focuses on the construction of a 2D dynamic model, taking into consideration the turbulent flux combustion reactions of syngas inside a combustion chamber and its displacement through the cylinder of a diesel engine model OM 447 LA converted to Otto cycle operation. The engine has a multi-spark ignition system. The geometry of both the chamber and cylinder is symmetric to a radius of 0.064 m and to a length of 0.17595 m. The simulation is carried out on only half of the system, with a premixed supply of the syngas and air. The supply temperature of the mixture is 336 K. The supply relation air/syngas ratio is 1.1:1, and the supply pressure of the mixture is 1 bar. The gaseous phase is modeled as a multi-component mixture comprised of carbon monoxide (CO), hydrogen (H_2), methane (CH_4), nitrogen (N_2), carbon dioxide (CO_2) and oxygen (O_2). The study describes a Computational Fluid Dynamic (CFD) numerical model, in which the conservation of matter, motion and energy equations are solved; in addition, sub-models are used to represent the turbulence intensity and the multiple reactions. The model predicts the profiles of syngas speed, temperature, chemical composition, pressure, and turbulence intensity for the gases when the working parameters and the supply characteristics are modified (air-syngas ratio, initial temperature of the mixture, initial pressure, compression ratio, and engine speed). The equation formulation is elliptic staggered. The result is a simple nonlinear map that resolves combustion time sequences using the commercial code CFD in PHOENICS.