An Asymptotic Solution Approach for Real time simulation of Aftertreatment Reactors in HiL environments
Santhosh Gundlapally, Gamma Technologies
Mathematical models are increasingly used as plant models for devising vehicle control strategies in Hardware in the Loop (HiL) environment. Aftertreatment (AT) reactors are complex in nature due to interaction between flow, pore diffusion and surface reactions. Pore diffusion plays an important role in the design and operation of both single and dual layer washcoated monoliths. Often AT reactor models are simplified by ignoring pore diffusion but this limits the range of validity of models. Numerical solution of pore diffusion is computationally demanding due extra computational work involved in solving of concentration profiles associated with the extra dimension through washcoat thickness. Recently Bissett (2015) proposed an approach based on asymptotic analysis as an alternative to numerical solution but was not extensively validated for wide range of operating conditions. In this work we assessed the validity of asymptotic solution for wide range of operating conditions encountered in different types of AT reactors (TWC, DOC, LNT, SCR and ASC). We also quantified the computational advantage of asymptotic solution for variety of models by simulating various emission test cycles. It is found that the asymptotic solution is several orders of magnitude faster than the full numerical solution and as expected dual layer washcoated monoliths benefit most from the asymptotic solution.