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Investigation on the Fuel and Engine Parameters that Affect the Half Mass Fraction Burned (CA50) Optimum Crank Angle
ISSN: 0148-7191, e-ISSN: 2688-3627
Published October 02, 2012 by SAE International in United States
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In-cylinder pressure measurements and indicating diagrams have proven to be a valuable research tool for the analysis of combustion in spark-ignition or compression-ignition engines. With the use of thermodynamic models, the rate of heat release and mass fraction burned curves are calculated, and from the latter the CA50 parameter (crank angle fifty), which is the angle in which 50% of the total fuel has been burned. The empirical process of obtaining the optimum start of combustion typically leads to a value of CA50 from 8° to 10° after top dead center. This paper attempts to numerically investigate which properties have an influence on this optimum CA50. A simple thermodynamic model was implemented which used the Wiebe function for the rate heat release. The CA50 was then evaluated for combustion duration in the base configuration and in a theoretical adiabatic engine. Results showed that the CA50 is mildly sensitive to combustion duration and highly sensitive to the wall heat transfer coefficient, reaching very low values (still always located after top dead center). These lower values provided higher work output in the model. The main conclusion is that the optimal combustion timing of 8° to 10° is due to a compromise between power, wall heat transfer and exhaust gas energy, which prevents lower values.
Citationde O. Carvalho, L., de Melo, T., and de Azevedo Cruz Neto, R., "Investigation on the Fuel and Engine Parameters that Affect the Half Mass Fraction Burned (CA50) Optimum Crank Angle," SAE Technical Paper 2012-36-0498, 2012, https://doi.org/10.4271/2012-36-0498.
- Sellnau, M. C. Matekunas, F. A. Battiston, P. A. et al. Cylinder-Pressure-Based Engine Control Using Pressure-Ratio-Management and Low-Cost Non-Intrusive Cylinder Pressure Sensors SAE Paper 2000-01-0932
- Ayala, F. A. Gerty, M. D. Heywood, J. B. Effects of Combustion Phasing, Relative Air-fuel Ratio, Compression Ratio, and Load on SI Engine Efficiency SAE Paper 2006-01-0229
- Ponti, F. Ravaglioli, V. Serra, G. Stola, F. “Instantaneous Engine Speed Measurement and Processing for MFB50 Evaluation,” SAE Int. J. Engines 2 2 235 244 2010 10.4271/2009-01-2747
- Zhu, G. G. Daniels, C. F. Winkelman, J. MBT Timing Detection and its Closed-Loop Control Using In-Cylinder Pressure Signal SAE Paper 2003-01-3266
- Patterson, J. A. A Technique for Processing Cylinder Pressure and Test Bed Data Sets for Engine Speed-Sweep Tests to Allow Reduced Testing Time with Enhanced Interpretation of Results SAE Paper 2008-01-3006
- Davis, S. D. Patterson, G. J. Cylinder Pressure Data Quality Checks and Procedures to Maximize Data Accuracy SAE Paper 2006-01-1346
- Corti, E Forte, C. Real-Time Combustion Phase Optimization of a PFI Gasoline Engine SAE Paper 2011-01-1415
- Eriksson, L. Spark Advance for Optimal Efficiency SAE Paper 1999-01-0548
- Ravaglioli, V. Moro, D. Serra, G. Ponti, F. MEB50 On-Board Evaluation Based on a Zero-Dimensional ROHR Model SAE Paper 2011-01-1420
- Luján, J. M. Bermúdez, V. Guardiola, C. Abbad, A. A methodology for combustion detection in diesel engines through in-cylinder pressure derivative signal Mechanical Systems and Signal Processing 24 2261 2275 2010
- Mladek, M. Onder, C. H. A Model for the Estimation of Inducted Air Mass and the Residual Gas Fraction using Cylinder Pressure Measurements SAE Paper 2000-01-0958
- Yoon, P. Park, S. Sunwoo, M. Ohm, I. Yoon, K. J. Closed-Loop Control of Spark Advance and Air-Fuel Ratio in SI Engines Using Cylinder Pressure SAE Paper 2000-01-0933