Methane/hydrogen fueling a spark-ignition engine for studying NO, CO and HC emissions with a research CFD code

Abstract Emissions of nitric oxide (NO), carbon monoxide (CO), and unburned hydrocarbons (HC) and their reaction mechanisms are investigated in a spark-ignition (SI) engine fueled with methane/hydrogen blends (hydrogen 30% by vol.). This analysis considers engine load variation through a variable equivalence ratio, with the application of an in-house research, three-dimensional computational fluid dynamics code (3D-CFD) for detailed in-cylinder simulations. The code’s combustion model includes the thermal NO mechanism, and other alternative NO production mechanisms, such as via the NNH and N 2 O species formation and the prompt NO mechanisms. Moreover, two CO formation models have been added, using two and three chemical equations, and their results are compared in order to identify the most appropriate for such combustion processes. Finally, no additional HC formation model is included, as HC emissions are directly calculated by the code escorted by the contribution of unburned fuel from the crevice regions, in which a phenomenological model is applied. Focus is also given on the spatial NO, CO and HC production pattern inside the cylinder during combustion and expansion periods. The numerical results are then compared with available measured data, in order to validate these emission formation models and investigate the production paths at such conditions and for variable equivalence ratio. The NO predictions are adequate and well captured, while the trend of CO and HC is adequately predicted especially for high equivalence ratio. The overall outcome is a numerical tool capable to predict with detail the in-cylinder processes and examine the local gas properties during flame propagation and pollutant emissions inside the combustion chamber for this case of high technological interest.

[1]  Dimitrios C. Rakopoulos,et al.  Comparison of Combustion, Performance, and Emissions of HSDI Diesel Engine Operating on Blends of Diesel Fuel with Ethanol, n-Butanol, or Butanol Isomer Ether DEE , 2015 .

[2]  Rolf D. Reitz,et al.  Development of an Ignition and Combustion Model for Spark-Ignition Engines , 2000 .

[3]  A. Agarwal,et al.  Experimental investigations of combustion, performance and emission characteristics of a hydrogen enriched natural gas fuelled prototype spark ignition engine , 2016 .

[4]  Qi Zhang,et al.  Effects of hydrogen on combustion characteristics of methane in air , 2014 .

[5]  Dimitrios C. Rakopoulos,et al.  Assessment of NOx Emissions during Transient Diesel Engine Operation with Biodiesel Blends , 2014 .

[6]  F. Moreno,et al.  Combustion behavior of a spark ignition engine fueled with synthetic gases derived from biogas , 2014 .

[7]  V. L. Zimont,et al.  Gas premixed combustion at high turbulence. Turbulent flame closure combustion model , 2000 .

[8]  T. C. Zannis,et al.  Thermodynamic analysis of combustion and pollutants formation in a wood-gas spark-ignited heavy-duty engine , 2013 .

[9]  Dimitrios C. Kyritsis,et al.  An experimental comparison of non-premixed bio-butanol flames with the corresponding flames of ethanol and methane , 2011 .

[10]  George Kosmadakis,et al.  Evaluation of a new computational fluid dynamics model for internal combustion engines using hydrogen under motoring conditions , 2009 .

[11]  Bo Zhang,et al.  Effect of hydrogen addition on combustion and emissions performance of a spark-ignited ethanol engine at idle and stoichiometric conditions , 2010 .

[12]  Yu Wang,et al.  Combustion and emission characteristics of a port-injection HCNG engine under various ignition timings , 2008 .

[13]  Emmanuel Kakaras,et al.  Comparative Evaluation of Two Straight Vegetable Oils and Their Methyl Ester Biodiesels as Fuel Extenders in HDDI Diesel Engines: Performance and Emissions , 2014 .

[14]  C. N. Michos,et al.  Availability analysis of a syngas fueled spark ignition engine using a multi-zone combustion model , 2008 .

[15]  F. Moreno,et al.  Combustion analysis of a spark ignition engine fueled with gaseous blends containing hydrogen , 2012 .

[16]  Dimitrios C. Rakopoulos,et al.  Characteristics of performance and emissions in high-speed direct injection diesel engine fueled with diethyl ether/diesel fuel blends , 2012 .

[17]  S. Verhelst,et al.  Combustion and emissions characteristics of a dual fuel engine operated on alternative gaseous fuels , 2013 .

[18]  Mirko Baratta,et al.  Development of a method for the estimation of the behavior of a CNG engine over the NEDC cycle and its application to quantify for the effect of hydrogen addition to methane operations , 2015 .

[19]  Chang-Gi Kim,et al.  Full load performance and emission characteristics of hydrogen-compressed natural gas engines with valve overlap changes , 2014 .

[20]  Roger Sierens,et al.  Local heat flux measurements in a hydrogen and methane spark ignition engine with a thermopile sensor , 2009 .

[21]  G. Soete.  Overall reaction rates of NO and N2 formation from fuel nitrogen , 1975 .

[22]  S. Verhelst,et al.  A quasi-dimensional model for SI engines fueled with gasoline–alcohol blends: Knock modeling , 2015 .

[23]  Sokratis Demesoukas,et al.  Near wall combustion modeling in spark ignition engines. Part B: Post-flame reactions , 2015 .

[24]  M. Harasek,et al.  NOx formation in natural gas combustion—a new simplified reaction scheme for CFD calculations , 2006 .

[25]  A. Konnov,et al.  Experimental and modelling study of the effect of elevated pressure on ethane and propane flames , 2016 .

[26]  B. Vaglieco,et al.  Experimental investigation on the combustion process in a spark ignition optically accessible engine fueled with methane/hydrogen blends , 2014 .

[27]  F. Moreno,et al.  Efficiency and emissions in a vehicle spark ignition engine fueled with hydrogen and methane blends , 2012 .

[28]  G. Lavoie,et al.  A Fundamental Model for Predicting Fuel Consumption, NOx and HC Emissions of the Conventional Spark-Ignited Engine , 1980 .

[29]  George Kosmadakis,et al.  Computational fluid dynamics investigation of alternative nitric oxide emission mechanisms in a hydrogen-fueled spark-ignition engine , 2014 .

[30]  C. Bowman.  Kinetics of pollutant formation and destruction in combustion , 1975 .

[31]  A. Dean,et al.  O + NNH: A possible new route for NOX formation in flames , 1995 .

[32]  A. Konnov,et al.  Temperature-dependent rate constant for the reaction NNH + O → NH + NO , 2001 .

[33]  J. Heywood,et al.  Experimental and Theoretical Study of Nitric Oxide Formation in Internal Combustion Engines , 1970 .

[34]  George Kosmadakis,et al.  Heat transfer and crevice flow in a hydrogen-fueled spark-ignition engine: Effect on the engine performance and NO exhaust emissions , 2013 .

[35]  Patrice Seers,et al.  Numerical comparison of premixed laminar flame velocity of methane and wood syngas , 2009 .

[36]  C. D. Rakopoulos,et al.  Computational Fluid Dynamics Study of Alternative Nitric-Oxide Emission Mechanisms in a Spark-Ignition Engine Fueled with Hydrogen and Operating in a Wide Range of Exhaust Gas Recirculation Rates for Load Control , 2015 .

[37]  A. Konnov.  On the relative importance of different routes forming NO in hydrogen flames , 2003 .

[38]  A. Konnov,et al.  Probe sampling measurements and modeling of nitric oxide formation in ethane + air flames , 2007 .

[39]  George Kosmadakis,et al.  Investigating the effect of crevice flow on internal combustion engines using a new simple crevice model implemented in a CFD code , 2011 .

[40]  A. Alkidas.  Combustion-chamber crevices: the major source of engine-out hydrocarbon emissions under fully warmed conditions , 1999 .

[41]  D. Kyritsis,et al.  Algorithmic determination of the mechanism through which H2O-dilution affects autoignition dynamics and NO formation in CH4/air mixtures , 2016 .

[42]  Dimitrios C. Kyritsis,et al.  Experimental Study of Steady Quasi-Cone-Jet Electrostatic Sprays of Biobutanol for Engine Applications , 2014 .

[43]  George Kosmadakis,et al.  Investigation of nitric oxide emission mechanisms in a SI engine fueled with methane/hydrogen blends using a research CFD code , 2015 .

[44]  D. Kyritsis,et al.  A combined experimental/computational investigation of stratified combustion in methane–air mixtures , 2007 .

[45]  Hakan Serhad Soyhan,et al.  Emission characteristics of an hydrogen–CH4 fuelled spark ignition engine , 2015 .

[46]  C. D. Rakopoulos,et al.  Generation of combustion irreversibilities in a spark ignition engine under biogas–hydrogen mixtures fueling , 2009 .

[47]  Dimitrios C. Kyritsis,et al.  Comparative Evaluation of Extinction through Strain among Three Alcoholic Butanol Isomers in Non-Premixed Counterflow Flames , 2014 .

[48]  C. P. Fenimore,et al.  Formation of nitric oxide in premixed hydrocarbon flames , 1971 .

[49]  Enrico Mattarelli,et al.  A quasi-dimensional combustion model for performance and emissions of SI engines running on hydrogen–methane blends , 2010 .

[50]  George Kosmadakis,et al.  Critical evaluation of current heat transfer models used in CFD in-cylinder engine simulations and establishment of a comprehensive wall-function formulation , 2010 .

[51]  Jerzy Chomiak,et al.  A Simple Model of Unsteady Turbulent Flame Propagation , 1997 .