Characterizing the thermal sensitivity of a gasoline homogeneous charge compression ignition engine with measurements of instantaneous wall temperature and heat flux

Abstract An experimental study was performed to provide qualitative and quantitative insight into the thermal effects on a gasoline-fuelled homogeneous charge compression ignition (HCCI) engine combustion. The single-cylinder engine utilized exhaust gas rebreathing to obtain large amounts of hot residual gas needed to promote ignition. In-cylinder pressure, heat release analysis, and exhaust emission measurement were employed for combustion diagnostics. Fast response thermocouples were embedded in the piston top and cylinder head surface to measure instantaneous wall temperature and heat flux, thus providing critical information about the thermal boundary conditions and a thorough understanding of the heat transfer process. Two parameters determining thermal conditions in the cylinder, i.e. intake charge temperature and wall temperature, were considered and their effect on ignition and burning rate in an HCCI engine was investigated through systematic experimentation. The approach allowed quantitative analysis, and separating qualitatively different effects on the core gas temperature from the effects of near-wall temperature stratification. The results show great sensitivity to changes in wall temperature and such like, but a somewhat weaker effect of intake charge temperature on HCCI combustion. Variations of combustion phasing and peak burn rates due to wall temperature changes can be compensated if the intake charge temperature is varied in the opposite direction and with a factor of 1.11. The combustion stability limit of the HCCI engine depends more on wall temperature than on intake charge temperature. Analysis of a large number of individual cycles indicates that decreasing intake temperature retards timing, and the burn rates change primarily as a function of ignition timing. In contrast, lowering the wall temperature led to greater reduction in the bulk burn rate and greater increase in cyclic variability than expected simply as a result of retarded ignition, thus indicating significance of the thermal stratification in the near-wall boundary layer.

[1]  Dennis N. Assanis,et al.  Comparing Enhanced Natural Thermal Stratification Against Retarded Combustion Phasing for Smoothing of HCCI Heat-Release Rates , 2004 .

[2]  Rolf D. Reitz,et al.  Experimental Investigation of Direct Injection-Gasoline for Premixed Compression Ignited Combustion Phasing Control , 2002 .

[3]  John E. Dec,et al.  Isolating the Effects of Fuel Chemistry on Combustion Phasing in an HCCI Engine and the Potential of Fuel Stratification for Ignition Control , 2004 .

[4]  Vern D. Overbye,et al.  Unsteady Heat Transfer in Engines , 1961 .

[5]  Norimasa Iida,et al.  Combustion Analysis of Natural Gas in a Four Stroke HCCI Engine Using Experiment and Elementary Reactions Calculation , 2003 .

[6]  Dennis N. Assanis,et al.  A thin-film thermocouple for transient heat transfer measurements in ceramic-coated combustion chambers , 1993 .

[7]  R. A. White,et al.  Combustion Chamber Temperature and Instantaneous Local Heat Flux Measurements in a Spark Ignition Engine , 1993 .

[8]  Bengt Johansson,et al.  The Effect of Intake Temperature on HCCI Operation Using Negative Valve Overlap , 2004 .

[9]  Kazuie Nishiwaki,et al.  Internal-combustion engine heat transfer , 1987 .

[10]  William H. Press,et al.  Numerical recipes in C , 2002 .

[11]  Michael F. J. Brunt,et al.  Evaluation of Techniques for Absolute Cylinder Pressure Correction , 1997 .

[12]  Mary Chrenka Opris,et al.  A Comparison of Time-Averaged Piston Temperatures and Surface Heat Flux Between a Direct-Fuel Injected and Carbureted Two-Stroke Engine , 1998 .

[13]  N. S. Jackson,et al.  Instantaneous Heat Transfer in a Highly Rated DI Truck Engine , 1990 .

[14]  Dennis N. Assanis,et al.  Evaluation of Alternative Thermocouple Designs for Transient Heat Transfer Measurements in Metal and Ceramic Engines , 1989 .

[15]  Zoran Filipi,et al.  New Heat Transfer Correlation for an HCCI Engine Derived from Measurements of Instantaneous Surface Heat Flux , 2004 .

[16]  John E. Dec,et al.  An Investigation of the Relationship Between Measured Intake Temperature, BDC Temperature, and Combustion Phasing for Premixed and DI HCCI Engines , 2004 .