Computing Optimal Heat Release Rates in Combustion Engines
The combustion process has a high impact on the engine efficiency, and
in the search for efficient engines it is of interest to study the
combustion. Optimization and optimal control theory is used to compute
the most efficient combustion profiles for single zone model with heat
transfer and crevice effects. A model is first developed and tuned to
experimental data, the model is a modification of the well known
Gatowski-model (Gatowski et.al 1984). This model is
selected since it gives a very good description of the in-cylinder
pressure, and thus the produced work, and achieves this with a low
computational complexity. This enables an efficient search method that
can maximize the work to be developed. First, smooth combustion
profiles are studied where the combustion is modeled using the Vibe
function, and parametric optimization is used to search for the
optimal profile. Then, the most efficient combustion process with a
completely free combustion is studied with theory and software for
optimal control. A parameter study is performed to analyze the impact
of crevice volume and air/fuel ratio $\lambda$. The results show that
the losses have a high impact on the behavior, which is natural, and
that the crevice effect has a very distinct effect on the optimal
combustion giving a two mode appearance similar to the Seiliger cycle.
Lars Eriksson and Martin Sivertsson
2015
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Senast uppdaterad: 2021-11-10
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