Experimental Study on Solid SCR Technology to Reduce NOx Emissions from Diesel Engines

Abstract

To solve the problems of low exhaust temperature NOx conversion efficiency of urea Selective Catalytic Reduction (SCR) and easy production of urea crystals during actual vehicle operation, this paper studies the effect of solid SCR on NOx emission on the engine bench. The experimental results show that for a solid SCR carrying the same reducing agent, its volume is only 1/3 the volume of urea SCR. When the exhaust temperature is 160°C, the NOx conversion efficiency of the solid SCR system can reach 40%. Based on the same ammonia-nitrogen ratio setting, the World Harmonized Steady Cycle (WHSC) NOx conversion efficiency is improved by 3.3%, and the World Harmonized Transient Cycle (WHTC) NOx conversion efficiency is increased by 4.5%. When the solid SCR injection temperature is reduced to 160°C, the NOx conversion efficiency is significantly improved, which is 9.7% and 15.5% higher than that of the 200°C solid SCR system and the urea SCR system, respectively, and the number of power base windows is between [0 20]. The NOx emission of diesel vehicles matching the urea SCR system is significantly higher, reaching 2.38 and 1.73 times that of the solid SCR system with a starting temperature of 160°C and 200°C, respectively.