Combustion Analysis of Ethanol in An HCCI Engine

Abstract

Improving fuel economy and reducing emissions are two major challenges being faced by the automotive industry. Alternative fuels and new combustion concepts are emerging to combat both pollution and fuel crises. Of late, the concept of Homogeneous Charge Compression Ignition, has been receiving increased attention due to its potential for simultaneously reducing fuel consumption, NO_x and Particulate Emissions. In particular, in HCCI engine research, where combustion is regarded to be a chemical-reaction-governed process, the importance of accurate chemical kinetic mechanisms and their computational efficiency is emphasized. This paper examines the HCCI of Ethanol (C₂H₅OH), investigating ignition trends as a function of initial temperature, initial pressure, and fuel additives in a variable volume reactor. The chemical kinetic mechanism of Ethanol was constructed using 57 species and 383 reactions in the CHEMKIN readable format for the analysis purpose. Combustion characteristics such as cylinder pressure rise, formation of species, and ignition delay characteristics were studied in Homogeneous Charge compression ignition engine and the analysis was done using COMSOL software. The results show that the inlet temperature of the fuel air mixture is a potential tuning parameter for ignition. An increase in pressure resulted in an increase in the species concentrations in the fuel-air mixture, resulting in the expected advance ignition times.