Runtime efficient simulation of monolith catalysts with a dual-layer washcoat

This paper demonstrates that the use of a solution-mapping approach can accelerate the simulation of a dual-layer ammonia oxidation catalyst by several orders of magnitude. In a first step, a 1-D + 1-D model of the dual-layer catalyst is set up. The results of this model are compared to the numerical solution of a 2-D model, and it is shown that the 1-D + 1-D model provides an accurate approximation of the full 2-D solution. In a second step, spline interpolation functions are constructed that map the solution of the mass balance equations for one axial volume element of the 1-D + 1-D model as a function of the inlet concentrations, temperature and residence time. During the runtime of the simulation, concentration profiles can be computed by simple successive calls of the interpolation function without the need for a numerical solver. The 5-dimensional spline functions reproduce the output concentrations of a reactor model with 35 axial volume elements with an accuracy of better than 1.25%. The use of the solution mapping reduces the computation time for a steady-state solution of the monolith model from 97.5 s down to 10 ms.