How simulation can help reduce auto-emissions.
With the growing number of environmental regulations in our society, demand exists to create technologies to reduce our emissions at the tail pipe. Simulation can play a key role in designing these environmental advancements.
One potential emission dropping technology is Selective Catalytic Reduction (SCR). In SCR, the NOx emissions are reacted into water and inert nitrogen using a catalytic reaction in the presence of ammonia.
However, when excess ammonia is injected into the SCR, or when there is inadequate catalyst surface available, the ammonia can slip into the atmosphere. Simulation is key to ensure the SCR will avoid “ammonia slip” when driving from the free flowing highway to the dense traffic jam.
As the reaction typically happens at 500 K (440 ͦF), changes in the engine’s load given the current road conditions can produce drastic stresses on the reaction and the structure of the components. The stress on the SCR’s structure is calculated as a diagram using CFD simulation into a FEA.
Total Deformation (left), von Mises Stress (center), & first-frequency (right).
You can also simulate reactions and display the results in a video format; this way designers can search for bottlenecks in the system or areas where there is no reaction taking place. Modifications can then be made and tested as needed, giving the ability to assess more designs in less time.
Simulation of a catalytic converter, like many other chemical reactions, will provide a level of information that physical testing cannot yet achieve. With this information you can produce lower costs, lead time, prototype testing and a truly optimized SCR design. Something which should help everyone breathe a cleaner sigh of relief.
Source and simulation image courtesy of ANSYS.
