A long breathing lean NOx trap for diesel after-treatment supplemental energy reduction

A long breathing strategy was investigated as a method for reducing the supplemental energy consumption of a diesel lean NOx trap (LNT). Empirical tests were performed on a heated flow bench set-up. The test results indicated that the LNT adsorption (breathing) time increased exponentially when the nitrogen oxide (NOx) level in the feed gas was reduced. Longer adsorptions led to supplemental energy savings due to less frequent LNT regeneration. In these tests, supplemental energy savings of over 70% were achieved with a long breathing LNT compared to a traditional LNT. Additional empirical tests investigated the concept of on-board hydrogen generation due to its potential benefits to an after-treatment system. The test findings revealed that the reformer temperature was a critical factor for on-board hydrogen generation. Further numerical and empirical tests revealed the benefits of utilizing a flow reversal system for hydrogen generation

Strategies for Enhanced After-Treatment Performance: Post Injection Characterization and Long Breathing with Low NOx Combustion

A novel long breathing technique was created to achieve ultra-low NOX emissions with reduced supplemental fuel consumption compared to conventional strategies. Long breathing refers to the use of in-cylinder NOX reduction to prolong the NOX storage (breathing) cycle of a lean NOX trap (LNT). Exhaust gas recirculation (EGR) was used with conventional diesel fuel and steady-state experimental tests identified that engine-out NOX emissions of 0.4 to 0.8 g/kW·hr were suitable for long breathing operation. The results indicated that the reduced engine-out NOX emissions significantly prolonged the NOX storage cycle and decreased the supplemental fuel consumption penalty of the LNT for all of the tested conditions