Search Results

Design and manufacturing engineers engaged in the conceptual and detail design stages of an aircraft have an ever increases number of tools and resources. However, these tools deal mainly with the physical structure and properties of the aircraft. Recently an increased effort has been made to take into account the producibil-ity and cost of an aircraft during the design phase. One of the tools being used by Lockheed Martin Tactical Aircraft Systems to accomplish this is Discrete Event Simulation. This form of simulation models dynamic production, information, and material flows. It enables an engineer to have greater visibility into the effects that he/ she makes on the overall aircraft production system. Machines and processes with different cost, speed, quality, and maintenance properties can be analyzed with respect to the system to justify their inclusion.

Cu-SSZ-13 catalysts are widely used for diesel aftertreatment applications for NOx (NO and NO2) abatement via selective catalytic reaction (SCR) due to their high conversion efficiency and excellent hydrothermal stability. Diesel engine exhaust contains small amounts of SOx due to the combustion of sulfur compounds in diesel fuel. The engine out SOx level mainly depends on the sulfur content in the diesel fuel. The presence of SOx from engine exhaust can deteriorate the SCR performance of Cu-SSZ-13 catalysts in real-world applications. This work is focused on the sulfur-induced deactivation process of a Cu-SSZ-13 catalyst under a range of simulated diesel engine operating conditions. Two catalyst deactivation modes, namely chemical poisoning and physical poisoning, are identified, primarily depending on the operating temperature. Chemical poisoning mainly results from the interaction between SOx and Cu species within the zeolite framework.