Mitigation of NOx and CO2 from diesel engine with EGR and carbon capture unit

The significant contribution of NOx and CO2 emissions with Diesel engines and stringent European Standard norms have compelled many researchers to seek new technologies for an effective solution. Exhaust gas recirculation (EGR) can control NOx emission but at the cost of increasing CO2 emission. This trade-off is addressed in this research work where the theoretical design of a Diesel engine retrofitted with devices for simultaneous mitigation of NOx and CO2 has been presented. The simulation of the combustion process of the Diesel engine has been performed by the commercial software ANSYS which indicates 32.9%, 50.63%, and 54.43% reduction of NO2 with 10%, 20%, and 30% EGR ratio, respectively, while the corresponding increase of CO2 is 4.76%, 9.52%, and 15.28%, respectively. The mitigation of this increased amount of CO2 has been demonstrated by carrying out experimental investigations on Diesel engine exhaust with carbon capture unit using two standalone absorbents, viz. aqueous ammonia (AQ_NH3) and mono-ethanol-amine (MEA) at five different brake power values. Average carbon capture efficiency is found to be 91% and 94% with AQ_NH3 and MEA, respectively. Further, the blend consisting of 67% of AQ_NH3 and 33% of MEA has also been investigated which shows 95% carbon capture efficiency. This work revealed that the EGR and carbon capture unit in the Diesel engine will be an effective solution to control NOx and CO2 emissions simultaneously and provide the basis for future research on the execution of stringent European Standard norms.

Automated summary

This research presents a theoretical design and experimental investigation of a Diesel engine retrofitted with devices for simultaneous mitigation of NOx and CO2 emissions. The results show that the combination of EGR and carbon capture unit can effectively reduce NOx emissions while capturing CO2, providing a potential solution to meet the stringent European Standard norms.