Session: 05-03: NOx Control for Alternative Fuels

Paper Number: 164513

164513 - Simultaneous Control of Unburned NH3 and NOx Emissions From High Load Dual-Fuel Ammonia Operation on a High-Speed Diesel Engine Using a Cu-SCR System 

Abstract: 

Dual-fuel ammonia (NH₃) strategies are being investigated as a promising way to utilize NH₃ as an alternative fuel for internal combustion engines in the maritime sector. One of the remaining barriers to implementing dual-fuel NH₃ combustion strategies is understanding ways to minimize unburned NH₃ and nitrogen oxide (NO_x) emissions from these engines, both of which are elevated relative to a conventional diesel baseline. Selective catalytic reduction (SCR) systems are widely used for lean NO_x emissions controls for engines across transportation and stationary energy applications. SCR systems use a reducing agent, such as NH₃, to react with NO_x in the exhaust, converting it into nitrogen and water. Typically, NH₃ is injected into the exhaust as a urea solution. In dual-fuel NH₃ engines, where unburned NH₃ is present in the exhaust, a SCR system could be used to mitigate both NH₃ and NO_x emissions. The presented work evaluates a commercial copper-zeolite SCR and ammonia slip catalyst (ASC) system, designed for on-road diesel engine applications, for controlling unburned NH₃ and NO_x emissions from dual-fuel NH₃ combustion engine. The aftertreatment system was installed downstream of a single-cylinder 4-stroke diesel engine with a 107 mm bore and a compression ratio of 20:1 that has been modified for dual-fuel ammonia use. The emissions were characterized using an FTIR for both late- and early-injection diesel pilot strategies over three air-fuel equivalence ratios spanning from 1.6 to 1.0 at a 1200 rpm, 12.7 bar IMEP_g condition (with greater than 95% ammonia energy substitution). Initial findings indicate that the SCR achieves more than 99% NO_x conversion with less than 50 ppm of NH₃ slip at air-fuel equivalence ratios greater than 1.4 at the operating condition investigated. However, these benefits are accompanied by an additional N₂O emissions that are formed  over the Cu-SCR.

Presenting Author: Daanish Tyrewala Oak Ridge National Laboratory

Presenting Author Biography: Dr. Daanish Tyrewala is a researcher in the Energy Sciences Directorate at the Oak Ridge National Laboratory. Dr. Tyrewala received his B.S. degree in Mechanical Engineering from Michigan Technological University located in Houghton, MI. He received an M.S. degree and Ph.D. degree in Mechanical Engineering with a Ph.D. minor in Energy Analysis and Policy from the University of Wisconsin-Madison.

Dr. Tyrewala's expertise lies in exploring the use of low lifecycle-carbon fuels such as methane, hydrogen, and ammonia for advanced dual-fuel combustion through experimental and chemical kinetic methods. He envisions a future where diverse solutions drive decarbonization in the global transportation sector. His experience includes working with Tesla’s Battery Abuse Research and Development team, where he focused on developing thermal runaway detection and mitigation strategies. With interests spanning both advanced internal combustion engines powered by low-lifecycle carbon fuels and battery safety research, he is dedicated to advancing sustainable transportation technologies.

Authors:

Daanish Tyrewala Oak Ridge National Laboratory
Vitaly Prikhodko Oak Ridge National Laboratory
Brian Kaul Oak Ridge National Laboratory
Scott Curran Oak Ridge National Laboratory