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In recent decades, the environment has been seriously polluted by the hazardous exhaust components of diesel engines. The international community, which is dedicated to preserving the harmony between nature and humanity, has taken this seriously and imposed strict regulations on Diesel engine manufacturers regarding the quantity of exhaust components from Diesel engines that may apply to the standards of EURO-VI. The SCR technology attempted to reduce the problem somewhat, but the associated problems of solid particle formation on the pipe walls, ammonia slip, and incomplete NOx reduction led to the development of new technology - solid selective catalytic reduction. The use of solid ammonium salt for ammonia generation has shown better results in NOx reduction and reduction of solid particle formation compared to SCR. However, it was not possible to fully resolve the ammonia slip issue. A uniform flow rate of ammonia through the SCR catalyst can reduce NOx efficiently. In this paper, the role of mixer design in achieving a uniform flow rate of ammonia is investigated in detail. The results show that an optimized mixer design leads to efficient reduction of NOx and thus reduces ammonia slip to a great extent. When the mixer is placed near the ammonia injection point, the most homogeneous ammonia distribution is achieved for flow through the SCR catalyst.

The rising rate of pollution in urban areas has become a worldwide concern in recent years. Diesel engines are considered one of the largest contributors to environmental pollution caused by exhaust emissions, and they are responsible for several health problems as well. Diesel engines contain carbon monoxide, carbon dioxide, unburned hydrocarbons, and oxides of nitrogen. The reduction of Nitric oxides (NOx) emission from diesel engine exhaust is currently being researched by automotive manufacturers. After much research, selective catalytic reduction (SCR) technology was discovered to be effective in reducing nitrogen oxide emission from diesel engine exhaust. This paper is an attempt to explore the problems associated with the use of selective catalytic reduction (SCR) and compares selective catalytic reduction (SCR) with the latest technology named solid selective catalytic reduction (SSCR) for efficient reduction of NOx emission from the exhaust of diesel engines. The issue of contamination, malfunctioning, and freezing of diesel exhaust fluid (DEF) at low temperatures are the major problems associated with the application of SCR. It is observed that by controlling the quantity of ammonia slip, SSCR can give better performance in the reduction of NOx emission from the exhaust of diesel engines.