Numerical study on effects of hydrogen direct injection on hydrogen mixture distribution,combustion and emissions of a gasoline/hydrogen SI engine under lean burn condition |
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| Affiliation: | 1. School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083, China;2. School of Transportation Science and Engineering, Beihang University, Beijing, 100191, China;3. School of Automotive and Engineering, Jilin Engineering Normal University, Changchun, 130052, China;1. State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun, Jilin, 130022, China;2. School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester, M13 9PL, UK;3. School of Computing, Science and Engineering, University of Salford, Manchester, M5 4WT, UK;1. Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran;2. College of Engineering Design and Physical Sciences, Brunel University London, Uxbridge, UB8 3PH, United Kingdom;3. Sechenov First Moscow State Medical University, Department of Prosthetic Dentistry, Moscow, Russia;1. School of Automotive and Transportation, Tianjin University of Technology and Education, Tianjin, 300222, China;2. State Key Laboratory of Engines, Tianjin University, Tianjin, 300072, China |
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| Abstract: | A numerical study on effects of hydrogen direct injection on hydrogen mixture distribution, combustion and emissions was presented for a gasoline/hydrogen SI engine. Under lean burn conditions, five different direct hydrogen injection timings were applied at low speeds and low loads on SI engines with direct hydrogen injection (HDI) and gasoline port injection. The results were showed as following: firstly, with the increase of hydrogen direct injection timing, the hydrogen concentration near the sparking plug first increases and then decreases, reaching the highest when hydrogen direct injection timing is 120°CA BTDC: Secondly, hydrogen can speed up the combustion rate. The main factor affecting the combustion rate and efficiency is the hydrogen concentration near the sparking plug: Thirdly, in comparing with gasoline, the NOX emissions with hydrogen addition increase by an average of 115%. For different hydrogen direct injection timings, the NOX emissions of 120°CA BTDC is the highest, which is 29.9% higher than the 75°CA BTDC. The hydrogen addition make the NOX emissions increase in two ways. On the one hand, the average temperature with hydrogen addition is higher. On the other hand, the temperature with hydrogen addition is not homogeneous, which makes the peak of temperature much higher. In a word, the main factor of NOX emissions is the size of high temperature zone in the cylinder: Finally, because the combustion is more complete, in comparing with gasoline, hydrogen addition can reduce the CO and HC emissions by 32.2% and 80.4% respectively. Since a more homogeneous hydrogen mixture distribution can influence a lager zone in the cylinder and reduce the wall quenching distance, these emissions decrease with the increase of hydrogen direct injection timing. The CO and HC emissions of 135°CA BTDC decrease by 41.5% and 71.4%, respectively, compared to 75°CA BTDC. |
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| Keywords: | Combined injection Hydrogen direct injection Direct injection timing Hydrogen mixture distribution Combustion Emission |
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