Numerical investigation on combustion regulation for a stoichiometric heavy-duty natural gas engine with hydrogen addition considering knock limitation |
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| Affiliation: | 1. CAS Key Laboratory of Green Process and Engineering Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;2. National Engineering Research Center of Green Recycling for Strategic Metal Resources, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;3. University of Chinese Academy of Sciences, Beijing 100049, China;4. Zhengzhou Institute of Emerging Industrial Technology, Zhengzhou 450003, China;1. Department of Metallurgical and Materials Engineering, IIT Madras, JAML, Chennai, 600036, TN, India;2. Department of Materials Science and Metallurgical Engineering, IIT Hyderabad, Kandi, 502285, TS, India;1. Department of Metallurgical and Materials Engineering, Karadeniz Technical University, 61040, Trabzon, Turkey;2. Department of Metallurgical and Materials Engineering, Gaziantep University, 27310, Gaziantep, Turkey;3. Laboratory for Nuclear and Plasma Physics, Vinča Institute of Nuclear Sciences, University of Belgrade, 11000 Belgrade, Serbia;4. Center of Excellence for Hydrogen and Renewable Energy Convince, Vinča Institute of Nuclear Sciences, University of Belgrade, POB 522, 11001 Belgrade, Serbia;1. Energy Materials Computing Center, School of Energy and Mechanical Engineering, Jiangxi University of Science and Technology, Nanchang, 330013, China;2. Faculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou, 341000, China;3. Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha, 410082, China;1. State Key Laboratory of Technology in Space Cryogenic Propellants, Beijing 100028;2. North China Institute of Science and Technology, Xueyuan Road, Langfang, Hebei, 065201, China;3. State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, 100081, Beijing, China |
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| Abstract: | Aiming to further improve the thermal efficiency and reduce NOx emissions in the stoichiometric hydrogen-enriched natural gas (NG) engine, a detailed 3-D simulation model of stoichiometric operation heavy-duty NG engine is built based on the actual boundary conditions from high load bench test. The superimposed methods for knock regulation, combustion and emission control, including Miller valve timing, hydrogen volume fraction and EGR rate were proposed and investigated comprehensively. It reveals that the typically bimodal characteristic of heat release rate (HRR) curve is caused by knock, which seriously restricts the performance improvement of stoichiometric NG engine under high load condition. To predict and control the occurrence of the second peak of HHR accurately, a new parameter BI is defined. Moreover, the Miller timing with 20°CA of the intake valve late closing shows better combustion performance within the knock limit, accompanied by a slight increase in NOx emissions. Additionally, the 5% hydrogen blend, coupled with the Miller cycle, can further enhance the indicated thermal efficiency (ITE) of the NG engine due to the stronger effects on acceleration of laminar flame propagation velocity than the promotion of end-gas auto-ignition. Besides, the great potential of EGR rate for balancing NOx and ITE is also confirmed in the heavy-duty hydrogen-enriched NG engine adopting Miller cycle. Compared to the original indexes, combing with the regulation strategies of intake valve late closing (20°CA), hydrogen addition (5%) and EGR (17%) are proved to increase the indicated thermal efficiency by 1.89% and reduce NOx emissions by 11.47% within the knock limit. |
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| Keywords: | Natural gas engine Hydrogen addition Knock Miller cycle |
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