An Experimental Study on NOx Reduction Efficiency and NH3 Conversion Efficiency under Various Conditions of Reductant Injection on SCR and AOC

Abstract : As the environmental regulation of vehicle emission is strengthened, investigations for NO x and PM reduction strategies are popularly conducted. Two current available technologies for continuous NO x reduction onboard diesel vehicles are Selective Catalytic Reduction (SCR) using aqueous urea and lean NO x trap (LNT) catalysts. The experiments were conducted to investigate the NO x reduction performance of SCR system which can control the ratio of NO/NO 2 , temperature and SV(space velocity), and the model gas was used which is similar to a diesel exhaust gas. The maximum reduction efficiency is indicated when the NO:NO 2 ratio is 1:1 and the SV is 30,000 h -1 in 300°C. Generally, ammonia slip from SCR reactors are rooted to incomplete conversion of NH 3 over the SCR. In this research, slip was occurred in 6cases (except low SV and NO:NO 2 ratio is 1:1) after SCR. Among 6 case of slip occurrence, the maximum conversion efficiency is observed when SV is 60,000 h -1 in 400°C.