1 An Investigation of surrogate fuel to represent EEE across varied intake pressures for HCCI Combustion Thursday, May 7, 2015 Mike Tiry, John Roberts, Shujin Jiang

2 Presentation Outline Background Testing –Experimental Testing –Numerical Testing –Comparison of Results Analysis –EEE Octane Index –Background Theory –Calculating of Octane Index Conclusions Acknowledgements and Questions

3 Background EEE has an octane rating of 93, thus is commonly modelled as a PRF93. EEE has aromatics (Toluene and Benzene) that were expected to cause EEE to have a different pressure dependency than a PRF blend. ComponentPRF 100 PRF 90 EEE RON+MON/ Iso-Octane N-heptane Toluene000.28

4 Experimental Test ParameterValue RPM1300 AFR55 Int. Temp.90 [C] Int. Pressure [kPa] Gross IMEP6-11 [bar] HCCI combustion was conducted with EEE, PRF100, and PRF90. Intake pressure was swept over possible operating range. Intake temperature and AFR were held constant. CA50 and load were allowed to vary. Experiment was done in the C15 lab to handle the high cylinder pressures, high PPRR, and to be able to blend fuels in cylinder. Emissions were negligible and constant for all cases. *iso-Octane and n-heptane were used as the primary reference fuels.

5 Numerical Test A Chemkin model with a Woschni heat transfer model was developed. The model was validated with the 260kPa, PRF100 experimental data point. After the model was validated, only the IVC temperature was used to match phasing. The 3 fuels were tested against 4 different mechanisms. The model under predicted the advancement of PRF90 but only slightly. The Chemkin results for EEE were what you would expect from a PRF93. *Initial model was correlated with the LLNL reduce gasoline mechanism. ComponentSpeciesReactions LLNL Full LLNL Reduced ERC PRF88250 Kalghatgi137633

6 Comparison of Exp. to Num. Results

7 The pressure dependency does not vary as expected with aromatics.

8 Further Analysis It was observed that EEE behaved as if it had a higher octane index than PRF100 (Neat Iso-Octane) This behaviors is in direct contradiction to the traditional measurement on octane index (OI):

9 Gasoline Reactivity Testing ASTM D Standard Test Method for Motor Octane Number of Spark-Ignition Engine Fuel ASTM D b Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel

10 Background Theory Kalghatgi, Gautam T. "Auto-Ignition Quality of Practical Fuels and Implications for Fuel Requirements of Future Si and Hcci Engines." SAE International, Print.

11 Calculation of Octane Index Kalghatgi, Gautam T. "Auto-Ignition Quality of Practical Fuels and Implications for Fuel Requirements of Future Si and Hcci Engines." SAE International, Print.

12 Calculation of Octane Index - Results Kalghatgi, Gautam T. "Auto-Ignition Quality of Practical Fuels and Implications for Fuel Requirements of Future Si and Hcci Engines." SAE International, Print.

13 Conclusions 1500 ComponentSpeciesReactions LLNL Full LLNL Reduced ERC PRF88250 Kalghatgi Gasoline fuels can be represented with PRF or TRF blends but their reactivity should be carefully calibrated. The traditional octane index may not be the best metric. All mechanisms need to be tuned to match the experimental data. The kalghatgi mechanism captured the pressure dependency seen in the experimental data but became less sensitive with the addition of Toluene. The other mechanisms were far less pressure dependent but toluene can be added with out impacting this dependency. The LLNL Full mechanism was the most detailed but performed the worst and took by far the longest.

14 Acknowledgements References: Gauthier, B. M., D. F. Davidson, and R. K. Hanson. "Shock Tube Determination of Ignition Delay Times in Full-Blend and Surrogate Fuel Mixtures." Combustion and Flame (2004): Print. Kalghatgi, Gautam, Hassan Babiker, and Jihad Badra. "A Simple Method to Predict Knock Using Toluene, N-Heptane and Iso- Octane Blends (Tprf) as Gasoline Surrogates." SAE Int. J. Engines 8.2 (2015): Print. Kalghatgi, Gautam T. "Auto-Ignition Quality of Practical Fuels and Implications for Fuel Requirements of Future Si and Hcci Engines." SAE International, Print. Mehl, Marco, and William J Pitz. "Experimental and Surrogate Modeling Study of Gasoline Ignition in a Rapid Compression Machine." Combustion and Flame (2012): Print. Kukkadapu, Goutham, et al. "Autoignition of Gasoline and Its Surrogates in a Rapid Compression Machine." Proceedings of the Combustion Institute 34.1 (2013): Print. Mehl, M., et al. "An Approach for Formulating Surrogates for Gasoline with Application toward a Reduced Surrogate Mechanism for Cfd Engine Modeling." Energy & Fuels (2011): Print. Mehl, M., et al. "Detailed Kinetic Modeling of Low-Temperature Heat Release for Prf Fuels in an Hcci Engine." SAE International, Print. Mehl, Marco, et al. "Kinetic Modeling of Gasoline Surrogate Components and Mixtures under Engine Conditions." Proceedings of the Combustion Institute 33.1 (2011): Print. Mehl, Marco, et al. "Detailed Kinetic Modeling of Conventional Gasoline at Highly Boosted Conditions and the Associated Intermediate Temperature Heat Release." SAE International, Print. Shao, Peng, and Chung K Law. "Ntc Affected Ignition in Non Premixed-Counterflow." Fall technical meeting of the Eastern States section of the combustion institute (2011). Print. ASTM D Standard Test Method for Motor Octane Number of Spark-Ignition Engine Fuel ASTM D b Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel

15 Questions?

16 Investigation in Chemkin (extra) It has also been suggested that it is appropriate to model gasoline as a blend of TPRF fuels. Sweeps of predicting CA50 in Chemkin were performed for PRF100, PRF90, and EEE. Kalghatgi, Gautam, Hassan Babiker, and Jihad Badra. "A Simple Method to Predict Knock Using Toluene, N-Heptane and Iso- Octane Blends (Tprf) as Gasoline Surrogates." SAE Int. J. Engines 8.2 (2015): Print. Using only Iso-octane and N- heptane PRF blend – ERC Mechanism Using Toluene, Iso-octane and N- heptane PRF blend – Kalghatgi Mechanism

17 Reaction Pathway Analysis (Iso-Octane) (extra) Stage 1Stage 2Stage 3 Stage 1Stage 2 Stage 3 Low Pressure (2.0 Bar) Iso- Octane Reaction Pathway High Pressure (3.5 Bar) Iso- Octane Reaction Pathway

18 Experimental (extra)

19 (extra) The late phasing of EEE resulted in IVC temperatures closest to the thermodynamic model. To push K negative – requires a TIVC of ~500 K – therefore neglecting heat transfer for the intake charge is appropriate This was verified with iso-octane in the model and gives a value of 100