Investigations on the effect of measurement errors on estimated combustion and performance parameters in HCCI combustion engine

Several parameters derived from heat release analysis are used for combustion diagnostics and control in internal combustion engines. It is important to tune the input parameters used in heat release calculations, in order to get correct estimation of heat release rate. In this study, tuning of input parameters is carried out by using cumulative heat release calculations of cylinder pressure during motoring. This tuning procedure uses offline iterative processing of motoring in-cylinder pressure data. The tuned parameters obtained from this method can also be utilized for online analysis of combustion parameters. Input parameters used in these investigations are intake air temperature, intake air pressure, phasing between the acquired pressure and crank angle position, compression ratio and scaling factor of heat transfer coefficient. Effect of error in these input parameters on estimated combustion and performance parameters like IMEP, combustion phasing, combustion duration, heat release rate, and maximum mean gas temperature are evaluated. The relative importance of measurement error in input parameters and its maximum expected error in the final results is analyzed in a HCCI combustion engine. Results shows that measurement errors in phasing between pressure and crank angle position, compression ratio and inlet air pressure affect estimated combustion and performance parameters significantly.

► Measurement errors in (i) TDC phasing, (ii) CR, (iii) Pi, (iv) Ti, and (v) heat transfer.
► Cumulative heat release is sensitive to errors in TDC location, CR and intake air pressure.
► ROHRmax is mainly affected by measurement errors in TDC location, CR and intake air pressure.
► Measurement error of 1 CAD in TDC location causes errors of 11.66% in IMEP and 1.23% in PMEP.
► Measurement errors in TDC location, CR and Pi are more critical for heat release analyses in HCCI engine.