Control Oriented Engine Model Development for Model-Based PPC Control

A model-based control approach is proposed to give proper reference for the feed-forward combustion control of Partially Pre-mixed Combustion (PPC) engines. The current study presents a simplified first principal model, which has been developed to provide a base estimation of the ignition properties. This model is used to describe the behavior of a single-cylinder heavy-duty diesel engine fueled with a mix of bio-butanol and n-heptane (80vol% bio-butanol and 20 vol% n-heptane). The model has been validated at 8 bar gross Indicated Mean Effective Pressure (gIMEP) in PPC mode. Inlet temperature and pressure have been varied to test the model capabilities. First the experiments were conducted to generate reference points with BH80 under PPC conditions. And then CFD simulations were conducted to give initial parameter set up, e.g. fuel distribution, zone dividing, for the multi-zone model. The in-cylinder pressure results show that, across the range of input conditions, the physics-based model is able to capture the auto-ignition characteristics and predicts the start of combustion within 3 ^oCA. CA50 characteristics has also been successfully captured, with root mean square error (RMSE) of 0.62 ^oCA and 2.2 ^oCA under the variation of boost pressure and temperature. The pressure rise rate and peak pressure have also been well predicted, with an RMSE of 2.54 bar/ ^oCA and 3.17 bar for boost pressure variation. As a first step towards model-based control, this model has been successfully validated over the effectiveness for effective, future combustion control.