Effects of ambient oxygen concentration on biodiesel and diesel spray combustion under simulated engine conditions

This study investigates the effect of ambient oxygen concentration on biodiesel and diesel spray combustion under simulated compression-ignition engine conditions in a constant-volume chamber. The apparent heat release rate (AHRR) is calculated based on the measured pressure. High-speed imaging of OH* chemiluminescence and natural luminosity (NL) is employed to visualize the combustion process. Temporally and spatially resolved NL and OH* contour plots are obtained. The result indicates that AHRR depends monotonically on the ambient oxygen concentration for both fuels. A lower oxygen concentration yields a slower AHRR increase rate, a lower peak AHRR value, but a higher AHRR value during the burn-out stage when compared with higher ambient oxygen concentration conditions. OH* chemiluminescence and NL contours indicate that biodiesel may experience a longer premixed-combustion duration. The 18% ambient O2 condition works better for biodiesel than diesel in reducing soot luminosity. With 12% O2, diesel combustion is significantly degraded. However, both fuels experience low temperature combustion at 10% O2. These results may imply that biodiesel is able to achieve the desired lower soot production under a moderate oxygen level with higher combustion efficiency, while diesel needs to be burned under very low ambient oxygen concentration for low soot production.

[1]  A. Tsolakis,et al.  Engine performance and emissions of a diesel engine operating on diesel-RME (rapeseed methyl ester) blends with EGR (exhaust gas recirculation) , 2007 .

[2]  Charles J. Mueller,et al.  An Experimental Investigation of the Origin of Increased NOx Emissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel , 2009 .

[3]  Avinash Kumar Agarwal,et al.  Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines , 2007 .

[4]  D. Tree,et al.  Soot processes in compression ignition engines , 2007 .

[5]  Song-Charng Kong,et al.  Characteristics of Engine Emissions Using Biodiesel Blends in Low-Temperature Combustion Regimes , 2008 .

[6]  Lyle M. Pickett,et al.  Low flame temperature limits for mixing-controlled Diesel combustion , 2005 .

[7]  Graham T. Reader,et al.  Energy efficiency improvement strategies for a diesel engine in low‐temperature combustion , 2009 .

[8]  Christoph Espey,et al.  Chemiluminescence Imaging of Autoignition in a DI Diesel Engine , 1998 .

[9]  Cherian A. Idicheria,et al.  Soot Formation in Diesel Combustion under High-EGR Conditions , 2005 .

[10]  A. Maiboom,et al.  Experimental study of various effects of exhaust gas recirculation (EGR) on combustion and emissions of an automotive direct injection diesel engine , 2008 .

[11]  Sanghoon Kook,et al.  Liquid length and vapor penetration of conventional, Fischer–Tropsch, coal-derived, and surrogate fuel sprays at high-temperature and high-pressure ambient conditions , 2012 .

[12]  Tan Piqiang,et al.  Exhaust emissions from a light-duty diesel engine with Jatropha biodiesel fuel , 2012 .

[13]  G. C. Mavropoulos,et al.  Effect of exhaust gas recirculation (EGR) temperature for various EGR rates on heavy duty DI diesel engine performance and emissions , 2008 .

[14]  André L. Boehman,et al.  The deconvolution of the thermal, dilution, and chemical effects of exhaust gas recirculation (EGR) on the reactivity of engine and flame soot , 2011 .

[15]  Tiegang Fang,et al.  Reducing NOx emissions from a biodiesel-fueled engine by use of low-temperature combustion. , 2008, Environmental science & technology.

[16]  Octavio Armas,et al.  Effect of biodiesel fuels on diesel engine emissions , 2008 .

[17]  K. Akihama,et al.  Mechanism of the Smokeless Rich Diesel Combustion by Reducing Temperature , 2001 .

[18]  Tiegang Fang,et al.  Biodiesel combustion in an optical HSDI diesel engine under low load premixed combustion conditions , 2009 .

[19]  Gregory M. Shaver,et al.  Soy-Biodiesel Impact on NOx Emissions and Fuel Economy for Diffusion-Dominated Combustion in a Turbo−Diesel Engine Incorporating Exhaust Gas Recirculation and Common Rail Fuel Injection , 2009 .

[20]  André L. Boehman,et al.  Impact of exhaust gas recirculation (EGR) on the oxidative reactivity of diesel engine soot , 2008 .

[21]  C. Westbrook,et al.  Detailed chemical kinetic oxidation mechanism for a biodiesel surrogate , 2007 .

[22]  Song-Charng Kong,et al.  Application of detailed chemistry and CFD for predicting direct injection HCCI engine combustion and emissions , 2002 .

[23]  S. Fernando,et al.  Flame temperature analysis of biodiesel blends and components , 2008 .

[24]  Juhun Song,et al.  Examination of the oxidation behavior of biodiesel soot , 2006 .

[25]  I. Glassman.  Soot formation in combustion processes , 1989 .

[26]  Dennis L. Siebers,et al.  Liquid-Phase Fuel Penetration in Diesel Sprays , 1998 .

[27]  J. G. Hawley,et al.  Diesel engine exhaust gas recirculation--a review on advanced and novel concepts , 2004 .

[28]  Jerald A. Caton,et al.  Evaluation of the equivalence ratio-temperature region of diesel soot precursor formation using a two-stage Lagrangian model , 2006 .

[29]  Ji Zhang,et al.  Spray Combustion of Biodiesel and Diesel in a Constant Volume Combustion Chamber , 2011 .

[30]  C. Lee,et al.  Effects of the exhaust gas recirculation rate and ambient gas temperature on the spray and combustion characteristics of soybean biodiesel and diesel , 2012 .

[31]  Raul Payri,et al.  Experimental Study on RME Blends: Liquid-Phase Fuel Penetration, Chemiluminescence, and Soot Luminosity in Diesel-Like Conditions , 2009 .

[32]  Tiegang Fang,et al.  High speed imaging of OH* chemiluminescence and natural luminosity of low temperature diesel spray combustion , 2012 .