Impact of EGR fraction on diesel engine performance considering heat loss and temperature‐dependent properties of the working fluid

Exhaust gas recirculation (EGR) to reduce feed gas NOx emission is common practice in modern diesel engines. Dilution of the intake air with cooled recirculated exhaust gas limits the production of in-cylinder NOx due to a lowering of the adiabatic flame temperature and a reduction in oxygen content of the intake mixture. EGR also reduces the mixture-averaged ratio of specific heats (γ) of the combustion charge leading to a reduction in the thermodynamic cycle efficiency. This trade-off between minimizing NOx production and maximizing cycle efficiency is of critical importance when calibrating EGR control schemes. Modeling tools that allow a quantitative analysis of this trade-off can be very beneficial in tuning EGR systems over a range of operating conditions. In this study, the systematic development of a model that allows an assessment of the impact of EGR on three parameters, namely (a) the thermodynamic cycle efficiency, (b) the mixture temperatures during the cycle and (c) the mixture-averaged γ, is presented. This is accomplished through a numerical solution of the energy equation while considering the effects of heat loss and temporally varying mixture-averaged values of γ. Results for a simple phenomenological model relating fuel-burn rate with EGR fraction and the impact of EGR fraction on NOx reduction are also included. Copyright © 2008 John Wiley & Sons, Ltd.

[1]  J. Holmes,et al.  Optimization of diesel engine design for combined heat and power , 1981 .

[2]  Bilal Akash,et al.  Thermodynamic modeling of spark-ignition engine: Effect of temperature dependent specific heats ☆ , 2006 .

[3]  G. Woschni.  A Universally Applicable Equation for the Instantaneous Heat Transfer Coefficient in the Internal Combustion Engine , 1967 .

[4]  Lingen Chen,et al.  Thermodynamic simulation of performance of an Otto cycle with heat transfer and variable specific heats of working fluid , 2005 .

[5]  Lingen Chen,et al.  Heat transfer effects on the net work output and efficiency characteristics for an air-standard Otto cycle , 1998 .

[6]  Sebastian Mosbach,et al.  HCCI Combustion Phasing Transient Control by Hydrogen-Rich Gas: Investigation Using a Fast Detailed-Chemistry Full-Cycle Model , 2009 .

[7]  C. Sayın,et al.  Influence of advanced injection timing on the performance and emissions of CI engine fueled with ethanol‐blended diesel fuel , 2008 .

[8]  Bilal Akash,et al.  Thermodynamic analysis of spark‐ignition engine using a gas mixture model for the working fluid , 2007 .

[9]  Robert J. Kee,et al.  CHEMKIN-III: A FORTRAN chemical kinetics package for the analysis of gas-phase chemical and plasma kinetics , 1996 .

[10]  Shuhn-Shyurng Hou,et al.  Comparison of performances of air standard Atkinson and Otto cycles with heat transfer considerations , 2007 .

[11]  G. Abd-Alla,et al.  Using exhaust gas recirculation in internal combustion engines: a review , 2002 .

[12]  H. A. Soliman,et al.  Effects of diluent admissions and intake air temperature in exhaust gas recirculation on the emissions of an indirect injection dual fuel engine , 2001 .

[13]  M. M. Osman,et al.  EXPERIMENTAL INVESTIGATION ON VARYING THE COMPRESSION RATIO OF SI ENGINE WORKING UNDER DIFFERENT ETHANOL–GASOLINE FUEL BLENDS , 1997 .

[14]  Constantine D. Rakopoulos,et al.  Evaluation of a spark ignition engine cycle using first and second law analysis techniques , 1993 .

[15]  Shuhn-Shyurng Hou,et al.  Heat transfer effects on the performance of an air standard Dual cycle , 2004 .

[16]  N. Mahalakshmi,et al.  Performance and emission characteristics of turpentine–diesel dual fuel engine and knock suppression using water diluents , 2007 .

[17]  Fengrui Sun,et al.  Effects of heat transfer and friction on the performance of an irreversible air-standard miller cycle , 2005 .

[18]  Dimitrios T. Hountalas,et al.  An experimental investigation of fuel‐injection‐pressure and engine‐speed effects on the performance and emission characteristics of a divided‐chamber diesel engine , 1993 .

[19]  Bilal Akash,et al.  Effect of heat transfer on the performance of an ait-standard diesel cycle , 2001 .