Numerical and Experimental Analysis of the Mass Transfer in Exhaust Gas Sensors

Within the scope of this work, the convective mass transfer to the zirconia sensor element of an exhaust oxygen sensor was analyzed experimentally and numerically. For the experimental setup, a heightened model of an oxygen sensor was built from Lucite^® considering the similarity theory. Mass transfer is measured based on the absorption of ammonia and subsequent immediate color reaction.

For the numerical investigation, a three-dimensional model of the test rig was built. To predict the flow pattern and the species transport inside the protection tubes, the commercial CFD-Code FLUENT^® is used. The model for the mass transfer to the surface is implemented through user-defined functions.