HC-LNT 2차 분사의 배기관내 분무 거동과 NOx 저감 특성

Abstract

NOx reduction system needs rich or stoichiometric operating condition periodically to reduce NOx. The HC(hydrocarbon) concentration in a diesel engine is so low that the HC is not sufficient for NOx conversion. It was proposed that a rich air fuel ratio in a diesel engine was realized by post fuel injection or supplemental fuel injection into the exhaust gas. A new method that optimizes a control of external HC injection to diesel exhaust pipe for HC type LNT(Lean NOx Trap) catalyst system has been developed. These catalysts are called the HC-LNT catalyst in this paper. The concentration and amount of HC can be controlled with the control of external injection. This research investigated interrelationship between spray behavior of hydrocarbons injected into the transparent exhaust pipe and NOx reduction characteristics. From this experiment, we obtained useful information about the optimum injection and position of HC injector to the exhaust pipe.