배기가스재순환이 산소부화화염의 CO 및 NO생성에 미치는 영향

초록

Two kinds of oxygen-enhanced-EGR flame have been evaluated numerically in counter diffusion flame geometry with a fixed strain rate. One is CH4/O2-CO2 EGR flame and the other is CH4/O2-CO2-H2O EGR flame. Recirculated gas composition was decided on a basis of stoichiometric quantity of product from 1 mole of methane and 2 mole of oxygen. A small amount of N2 is included in oxidizer stream, in order to consider the inevitable N2 contamination by O2 production process or air infiltration. Results show that the inclusion of H2O in recirculated gas promotes the conversion reaction from CO to CO2. Under the same flame temperature condition, the EINO of two flames can be maintained at nearly same level, but the EICO of CH4/O2-CO2-H2O EGR flame becomes much less than that of CH4/O2-CO2 EGR flame. CH4/O2-CO2-H2O EGR combustion is expected to overcome the shortcomings of abrupt increment of EINO in oxygen-enhanced combustion with accomplishing higher temperature than that of CH4/Air flame. The temperature of recirculated gas should be chosen very carefully, because NO emission is very sensitive to an increment of temperature.