열교환기가 촉매온도에 미치는 영향에 관한 연구

Abstract

The main challenge in the aftertreatment system is to reduce the enginer cold-start emissions. close-coupled catalyst(CCC) provides fast light-off time by utilizing the energy in the exhaust gas. however, in case the engine is operated at high engine speed and load condition, the catalytic converter may become damaged and eventually deactivated through thermal aging. excess fuel is sometimes supplied intentionally to lower the exhaust gas temperature avoiding the thermal aging. this sacrifices the fuel economy and exhaust emissions. this paper describes the results of an exhaust heat exchanger to lower the exhaust gas temperature mainly under high load conditions. the heat exchanger was installed between exhaust manifold and the inlet of close-coupled catalytic converter. the exhaust heat exchanger successfully decreased the exhaust gas temperature, which eliminated the requirement of fuel enrichment under high load conditions. however, cooling of exhaust gas through the heat exchanger may cause the deterioration of exhaust emissions at cold start due to the increment of catalyst light-off time. the light-off time was found to increase by 18 seconds in EC mode test. hydrocarbon emission was also increased by 0.021g/km though it still meets the euro-IV regulation