Self-tuning gross heat release computation for internal combustion engines

The paper describes a novel method for self-tuning gross heat release computation in internal combustion engines suitable for both online usage in combustion phasing control applications and post-processing of cylinder pressure measurements. The method estimates the polytropic exponents and cylinder pressure offsets immediately preceding and succeeding the combustion event, respectively, using a fast nonlinear least-squares method. The polytropic exponent and the pressure offset are subsequently interpolated during the combustion event and a net heat release computation is performed based on the interpolated exponent and pressure. The result is a self-tuning gross heat release algorithm with no need to model heat losses, crevice losses and blow-by explicitly.