Hydrogen effects on NOx emissions and brake thermal efficiency in a diesel engine under low-temperat

Abstract Cooled and heavy exhaust gas recirculation (EGR) has been used to control NOx emissions from diesel engines, but its application has been limited by low thermal efficiency or high unburned hydrocarbon emissions. In this study, hydrogen was added into the intake manifold of a diesel engine to investigate its effect on NOx emissions and thermal efficiency under low-temperature and heavy-EGR conditions. The energy content of the introduced hydrogen was varied from an equivalent of 2–10% of the total fuel’s lower heating value. A test engine was operated at a constant diesel fuel injection rate and engine speed to maintain the same engine control unit (ECU) parameters, such as injection time, while observing changes in the carbon dioxide produced due to variations in the hydrogen supply. Additionally, the EGR system was modified to control the EGR ratio. The temperature of the intake gas manifold was controlled by both the EGR cooler and the inter-cooling devices to maintain a temperature of 25 °C. Exhaust NOx emissions were measured for different hydrogen flow rates at a constant EGR ratio. The test results demonstrated that the supplied hydrogen reduced the specific NOx emissions at a given EGR ratio while increasing the brake thermal efficiency. This behavior was observed over constant EGR ratios of 2, 16, and 31%. The rate of NOx reduction due to hydrogen addition increased at higher EGR ratios compared with pure diesel combustion at the same EGR ratio. At an EGR ratio of 31%, when the hydrogen equivalent to 10% of the total fuel’s lower heating value was supplied, the specific NOx was lowered by 25%, and there was a slight increase in the brake thermal efficiency. This behavior was investigated by measuring and analyzing changes in the exhaust gas composition, including oxygen, carbon dioxide, and water vapor.

[1]  Martin Mueller,et al.  General Air Fuel Ratio and EGR Definitions and their Calculation from Emissions , 2010 .

[2]  William M. Silvis,et al.  An Algorithm for Calculating the Air/Fuel Ratio from Exhaust Emissions , 1997 .

[3]  Carlos Guardiola,et al.  A methodology for combustion detection in diesel engines through in-cylinder pressure derivative signal , 2010 .

[4]  Shuofeng Wang,et al.  Effect of hydrogen addition on combustion and emissions performance of a spark ignition gasoline engine at lean conditions , 2009 .

[5]  G. Nagarajan,et al.  An experimental investigation on DI diesel engine with hydrogen fuel , 2008 .

[6]  R. Steeper,et al.  The hydrogen-fueled internal combustion engine : a technical review. , 2006 .

[7]  G. Nagarajan,et al.  An experimental investigation of hydrogen-enriched air induction in a diesel engine system , 2008 .

[8]  J. Tuzson,et al.  Reducing Gas Turbine Emissions Through Hydrogen-Enhanced, Steam-Injected Combustion , 1996 .

[9]  M. Duoba,et al.  Fuel economy and emissions evaluation of BMW Hydrogen 7 Mono-Fuel demonstration vehicles , 2008 .

[10]  Daniel C. Haworth,et al.  Hydrogen assisted diesel combustion , 2010 .

[11]  Walter Knecht,et al.  Diesel engine development in view of reduced emission standards , 2008 .

[12]  Mingfa Yao,et al.  Progress and recent trends in homogeneous charge compression ignition (HCCI) engines , 2009 .

[13]  S. M. Aithal,et al.  Modeling of NOx formation in diesel engines using finite-rate chemical kinetics , 2010 .

[14]  S. M. Aithal,et al.  Impact of EGR fraction on diesel engine performance considering heat loss and temperature‐dependent properties of the working fluid , 2009 .

[15]  Athanasios Tsolakis,et al.  Promoting hydrocarbon-SCR of NOx in diesel engine exhaust by hydrogen and fuel reforming , 2009 .

[16]  A. Megaritis,et al.  Partially premixed charge compression ignition engine with on-board H2 production by exhaust gas fuel reforming of diesel and biodiesel , 2005 .

[17]  Daniel C. Haworth,et al.  Investigation of a hydrogen-assisted combustion system for a light-duty diesel vehicle , 2008 .

[18]  Franck Vangraefschepe,et al.  Formation of Unburned Hydrocarbons in Low Temperature Diesel Combustion , 2009 .

[19]  S. Turns.  An Introduction to Combustion: Concepts and Applications , 2000 .

[20]  R. Mikalsen,et al.  An experimental study of a direct injection compression ignition hydrogen engine , 2009 .

[21]  James W. Heffel,et al.  NOx emission and performance data for a hydrogen fueled internal combustion engine at 1500 rpm using exhaust gas recirculation , 2003 .

[22]  G. Nagarajan,et al.  An experimental investigation on hydrogen as a dual fuel for diesel engine system with exhaust gas recirculation technique , 2008 .

[23]  S. Szwaja,et al.  Hydrogen combustion in a compression ignition diesel engine , 2009 .

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

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

[26]  J. Storey,et al.  Experimental Evaluation of SI Engine Operation Supplemented by Hydrogen Rich Gas from a Compact Plasma Boosted Reformer , 2000 .

[27]  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 .

[28]  Peter Pfeifer,et al.  Reforming of diesel fuel in a micro reactor for APU systems , 2008 .

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

[30]  T. Johnson.  Review of Diesel Emissions and Control , 2010 .

[31]  Nafiz Kahraman,et al.  Investigation of cylinder pressure for H2/CH4 mixtures at different loads , 2009 .

[32]  M. Masood,et al.  Computer simulation of hydrogen–diesel dual fuel exhaust gas emissions with experimental verification , 2008 .

[33]  Nafiz Kahraman,et al.  Experimental study on a spark ignition engine fuelled by methane–hydrogen mixtures , 2007 .

[34]  N. Clark,et al.  An experimental investigation of the combustion process of a heavy-duty diesel engine enriched with H2 , 2010 .

[35]  Nigel N. Clark,et al.  An experimental investigation of H2 emissions of a 2004 heavy-duty diesel engine supplemented with H2 , 2010 .

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

[37]  Junmin Wang.  Air fraction estimation for multiple combustion mode diesel engines with dual-loop EGR systems , 2008 .

[38]  P. Bose,et al.  An experimental investigation on engine performance and emissions of a single cylinder diesel engine using hydrogen as inducted fuel and diesel as injected fuel with exhaust gas recirculation , 2009 .

[39]  Ricardo Novella,et al.  Study on Low Temperature Combustion for Light-Duty Diesel Engines , 2010 .

[40]  Technologies for Improved Emission Potential in a Small Displacement Volume Passenger Diesel Engine , 2009 .

[41]  John E. Dec,et al.  An investigation into lowest acceptable combustion temperatures for hydrocarbon fuels in HCCI engines , 2005 .

[42]  A. Tsolakis,et al.  Low-Load Dual-Fuel Compression Ignition (CI) Engine Operation with an On-Board Reformer and a Diesel Oxidation Catalyst: Effects on Engine Performance and Emissions , 2010 .

[43]  Haiyong Peng,et al.  Effects of exhaust gas recirculation (EGR) on combustion and emissions during cold start of direct injection (DI) diesel engine , 2008 .

[44]  G. Nagarajan,et al.  Experimental investigation of hydrogen port fuel injection in DI diesel engine , 2007 .

[45]  Cheolwoong Park,et al.  The influence of hydrogen-enriched gas on the performance of lean NOx trap catalyst for a light-duty diesel engine , 2010 .

[46]  Shuji Kimura,et al.  New Combustion Concept for Ultra-Clean and High-Efficiency Small DI Diesel Engines , 1999 .

[47]  A. Megaritis,et al.  Low temperature exhaust gas fuel reforming of diesel fuel , 2004 .