The UA2 Air-Assisted Urea Dosing System is a reductant delivery system that accurately injects a 32.5% solution of urea in water, also known as Diesel Exhaust Fluid (DEF) or AdBlue™, into the exhaust stream. Utilizing heat from the exhaust, the urea mixes and then decomposes into ammonia. The ammonia reacts with the SCR catalyst, converting NOx in the exhaust stream into harmless nitrogen and water. To ensure performance and maximize the environmental benefits of this system, Cummins employs advanced control technology.

The system is designed to help meet emissions regulations in emerging markets such as the National Standard 4/5 in China and the Bharat Stage 4 standard in India. The product will also support the global emission standards of North America, Europe, and South America.

This system allows for the ability to tune engines for improved fuel economy or to reduce the size of the SCR through uniformity index or ammonia slip catalysts. This dosing technology ensures efficient conversion to ammonia and prevention of urea build-up in the system, increasing the durability and reliability of the aftertreatment system. To achieve this, the air-assisted technology provides a smaller uniform urea droplet size through a centerline injection. In addition to reducing deposit formation, this system provides better performance than competitive systems with improved NOx conversion efficiency for comparative size catalysts.

 

Urea Supply Module

The urea supply module is a high-accuracy unit for injecting urea into the exhaust aftertreatment system. A control module calculates the exact dosing rate of urea based on various engine conditions, and the urea mixes with air from the vehicle compressed air. Atomized urea is then sent through the Injection Nozzle into the exhaust system, upstream of the SCR catalyst.

 

Injection Nozzle

The injection Nnzzle is a robust component that delivers urea and air mixture upstream of the SCR catalyst. The design allows injection in the center of the exhaust gas flow, which minimizes the risk of deposits. A relatively large orifice sizing in the nozzle also provides exceptional tolerance to contaminants.

  Injection Nozzle

Aftertreatment Control Module

The aftertreatment control module translates datalink-commanded dosing rates into supply module inputs to accurately deliver the required dosing quantities. The independent aftertreatment control module can also be used to control other engineered components in the engine or aftertreatment system.