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

To solve the problems of low exhaust temperature NO
_x
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 NO
_x
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 NO
_x
conversion efficiency of the solid SCR system can reach 40%. Based on the same ammonia-nitrogen ratio setting, the World Harmonized Steady Cycle (WHSC) NO
_x
conversion efficiency is improved by 3.3%, and the World Harmonized Transient Cycle (WHTC) NO
_x
conversion efficiency is increased by 4.5%. When the solid SCR injection temperature is reduced to 160°C, the NO
_x
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 NO
_x
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.