Review of Improving the NOx Conversion Efficiency in Various Diesel Engines fitted with SCR System Technology

Abstract

The diesel engine is utilized in most commercial vehicles to carry items from various firms; nevertheless, diesel engines emit massive amounts of nitrogen oxides (NOx) which are harmful to human health. A typical approach for reducing NOx emissions from diesel engines is the selective catalytic reduction (SCR) system; however, several reasons make reducing NOx emissions a challenge: urea particles frequently become solid in the injector and difficult to disseminate across the system; the injector frequently struggles to spray the smaller particles of urea; the larger urea particles from the injector readily cling to the system; it is also difficult to evaporate urea droplets because of the exhaust and wall temperatures (Tw), resulting in an increase in solid deposits in the system, uncontrolled ammonia water solution injection, and NOx emissions problems. The light-duty diesel engine (LDD), medium-duty diesel engine (MDD), heavy-duty diesel engine (HDD), and marine diesel engine use different treatments to optimize NOx conversion efficiency in the SCR system. This review analyzes several studies in the literature which aim to increase NOx conversion in different diesel engine types. The approach and methods demonstrated in this study provide a suitable starting point for future research into reducing NOx emissions from diesel engines, particularly for engines with comparable specifications.

Integrated catalytic systems for simultaneous NOx and PM reduction: A comprehensive evaluation of synergistic performance and combustion waste energy utilization

“…Additionally, side reactions can lead to the formation of nitrous oxide (N 2 O), a potent greenhouse gas with a global warming potential 298 times higher than carbon dioxide. These challenges necessitate the development of advanced SCR catalysts with improved low-temperature activity, sulfur tolerance, and thermal stability (Wardana MKA et al 2023). Lean NOx traps, which store NOx under lean conditions and reduce it to nitrogen under rich conditions, also face challenges in terms of storage capacity, regeneration e ciency, and durability.…”

Particulate Matter (PM) and Parent, Nitrated and Oxygenated Polycyclic Aromatic Hydrocarbon (PAH) Emissions of Emulsified Heavy Fuel Oil in Marine Low-Speed Main Engine

“…Outside of ECAs, known as non-ECA zones, ships are required to comply with the Tier I or Tier II standards, depending on the engine type and the year of construction. Depending on the catalyst utilized, SCR techniques encompass NH 3 -SCR, CO-SCR, HC-SCR, and H 2 -SCR and are a focal point of current discussions [ 5 , 6 , 7 ]. However, SCR systems necessitate precise operational conditions and are prone to challenges stemming from catalysts and reducing agent leakage.…”