한국기계연구 원 그린동력연구실1)․과학기술연합대학원대학 교 환경에너지기계공학과2) Emission Characteristics of HCNG Engine with Compression Ratio Change

Abstract: Compression ratio is an important factor affecting engine performance and emission characteristics since thermal efficiency of spark ignition engine can be theoretically improved by increasing compression ratio. In order to evaluate the effect of compression ratio change in HCNG engine, natural gas engine was employed using HCNG30 (CNG 70 vol%, hydrogen 30 vol%). Combustion and emission characteristics of CNG and HCNG fuel was analyzed with respect to the change of compression ratio at each operating condition. The results showed that thermal efficiency improved and CH4, CO2 emission decreased with the increase in compression ratio while NOx emissions were decreased at a certain excess air ratio condition. Higher thermal efficiency and further reduction of exhaust emission