Physically Based Models for Predicting Exhaust Temperatures in SI Engines
To have knowledge about the gas and material temperatures in the exhaust system
of today’s vehicles is of great importance. These temperatures need to be
known for component protection, control- and diagnostic purposes. Today mostly
map-based models are used which are not accurate enough and difficult to tune
since it consist of many parameters.
In this thesis physically based models are developed for several components in
the exhaust system. The models are derived through energy balances and are
more intuitive compared to the current map-based models. The developed models
are parameterized and validated with measurements from wind tunnel experiments
and driving scenarios on an outdoor track.
The engine out model is modeled theoretically and is therefore not parameterized
or validated. The model for the temperature drop over the exhaust manifold
could not be validated due to the pulsations occurring in the exhaust manifold,
however suggestions on how to solve this problem are given in this report. The
models for the turbocharger, the catalyst and the downpipe are parameterized
and validated with good results in this thesis. The mean absolute error for the
validation data set for the turbocharger is 0.46 % and 1.01 % for the catalyst. The
mean absolute percentage error for the downpipe is 1.07 %.
Andrej Verem and Hiren Kerai
2016
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