Organic acids emissions from natural-gas-fed engines

A natural-gas-fed spark-ignition engine, operating under lean conditions, i s used for the study of the organic acids exhaust emissions. These pollutan ts are collected by passing a sample of exhaust gas into deionised water. T he final solution is directly analysed by HPLC/UV at 204 nm. Only formic ac id is emitted in detectable concentration under the experimental conditions used. Its concentration decreases with the three engine operating paramete rs studied. spark advance, volumetric efficiency and fuel/air equivalence r atio. Exhaust formic acid concentration is also linked with exhaust oxygen concentration and exhaust temperature. A comparison with other engines (SI engines fed with gasoline and compression ignition engines) from bibliograp hic data proves that natural-gas-fed engines emit less organic acids than t he other two types of engines. (C) 2000 Elsevier Science Ltd. All rights re served.