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学者姓名：纪常伟
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Abstract ：
Although pure hydrogen engines can achieve zero carbon and extremely low NOx emissions under ultra-lean combustion conditions, there are limitations with combustion stability and power performance. This paper combines turbulent jet ignition (TJI) and variable valve timing (VVT) technology, which not only improves the power output of pure hydrogen engines under ultra-lean combustion conditions but also ensures the engine's stable operation. Therefore, this research reveals the working characteristics of TJI engines under lean conditions through numerical methods and explores the optimization characteristics of VVT on engine power performance and stability through experiments. The results indicate that TJI utilizes strong turbulence and multiple-point ignition to improve the efficiency of the mixture and combustion speed, ensuring reliable ignition capability under ultra-lean operating and achieving a stable and effective combustion process. According to the experimental results, the combination of TJI with VVT technology can ensure engine cyclic-variability of less than 1.5 % and the maximum values of Brake mean effective pressure (BMEP) and Brake thermal efficiency (BTE) are 4.5 bar and 41.6 %, respectively. This innovative technology combination not only enables the efficient and ecofriendly development of the transportation industry but also holds significant importance for promoting carbon-free fuels and environmental protection in the future.
Keyword ：
Turbulent jet ignition Turbulent jet ignition Hydrogen Hydrogen Variable valve timing Variable valve timing Low emission Low emission Ultra-lean combustion Ultra-lean combustion
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| GB/T 7714 | Qiang, Yanfei , Jin, Kai , Zhao, Shihao et al. Optimization of power performance and combustion stability of ultra-lean combustion in hydrogen fuel engines through combined turbulent jet ignition and variable valve timing [J]. | FUEL , 2024 , 381 . |
| MLA | Qiang, Yanfei et al. "Optimization of power performance and combustion stability of ultra-lean combustion in hydrogen fuel engines through combined turbulent jet ignition and variable valve timing" . | FUEL 381 (2024) . |
| APA | Qiang, Yanfei , Jin, Kai , Zhao, Shihao , Cai, Jichun , Su, Fangxu , Wang, Shuofeng et al. Optimization of power performance and combustion stability of ultra-lean combustion in hydrogen fuel engines through combined turbulent jet ignition and variable valve timing . | FUEL , 2024 , 381 . |
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Abstract ：
Ammonia (NH3) is a potential alternative fuel for internal combustion engines to achieve zero-carbon emissions. And partial fuel dissociating is a feasible strategy to improve the reactivity of NH3, the hydrogen (H2) generated by dissociation can effectively promote the combustion of NH3. This study aims to experimentally investigate the ignition and combustion characteristics of partially dissociated NH3 ignited by passive turbulent jet ignition. The effects of the dissociation ratio and equivalence ratio were analyzed. The results show that the dissociation of NH3 improves the ignition and combustion performance of NH3, reflected in lower ignition delay and combustion duration. In addition, as the dissociation ratio increases, the ignition mechanism in the main chamber changes from jet ignition to flame ignition, which can significantly reduce the ignition delay. Lean conditions are more conducive to achieving flame ignition, the jet ignition mechanism on the rich side leads to a higher ignition delay compared to lean conditions at low dissociation ratios. However, the lean mixture shows a higher combustion duration due to its low reactivity. The inhibiting effect of additional nitrogen (N2) increases with the dissociation ratio, but the ignition mechanism and flame propagation in the main chamber are not significantly affected.
Keyword ：
Ammonia Ammonia Passive pre -chamber Passive pre -chamber Combustion characteristic Combustion characteristic Partial dissociation Partial dissociation Turbulent jet ignition Turbulent jet ignition
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| GB/T 7714 | Wang, Zhe , Zhang, Tianyue , Wang, Du et al. Experimental investigation on the combustion characteristics of partially dissociated ammonia ignited by passive turbulent jet ignition [J]. | APPLIED THERMAL ENGINEERING , 2024 , 247 . |
| MLA | Wang, Zhe et al. "Experimental investigation on the combustion characteristics of partially dissociated ammonia ignited by passive turbulent jet ignition" . | APPLIED THERMAL ENGINEERING 247 (2024) . |
| APA | Wang, Zhe , Zhang, Tianyue , Wang, Du , Wang, Shuofeng , Ji, Changwei , Wang, Huaiyu et al. Experimental investigation on the combustion characteristics of partially dissociated ammonia ignited by passive turbulent jet ignition . | APPLIED THERMAL ENGINEERING , 2024 , 247 . |
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Abstract ：
Amid growing environmental concerns, hydrogen (H2) is emerging as a prospective alternative fuel for driving internal combustion engines. Employing lean combustion technology in tandem with turbulent jet ignition (TJI) has the potential to enhance combustion rates while mitigating NOx emissions. Therefore, an experiment was developed to investigate the combustion characteristics of ultra-lean premixed H2/air by TJI. An active prechamber (PC) with an additional H2 supply was selected. Moreover, the effect of nozzle structures and equivalence ratio was discussed. The results show that with a nozzle diameter of 3 mm and an elevation of phi PC to 1.4, the lean flammability limit is extended to an equivalence ratio of 0.13, with a consistently stabilized ignition delay within 4 ms. Increasing the nozzle number also extends the lean flammability limit, but it incurs higher energy losses. Additionally, two ignition mechanisms exist in TJI: flame ignition and combined ignition. The transition from flame ignition to combined ignition commonly occurs when the equivalence ratio of the main chamber drops below 0.3. This transition typically results in higher peak pressures and burnt fuel ratio, lower combustion duration, and longer ignition delay.
Keyword ：
Turbulent jet ignition Turbulent jet ignition Active pre-chamber Active pre-chamber Ignition characteristic Ignition characteristic Hydrogen Hydrogen Ignition mechanism Ignition mechanism
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| GB/T 7714 | Zhang, Tianyue , Ji, Changwei , Wang, Zhe et al. Experimental investigation on the combustion characteristics of ultra-lean premixed hydrogen/air using turbulent jet ignition [J]. | ENERGY , 2024 , 293 . |
| MLA | Zhang, Tianyue et al. "Experimental investigation on the combustion characteristics of ultra-lean premixed hydrogen/air using turbulent jet ignition" . | ENERGY 293 (2024) . |
| APA | Zhang, Tianyue , Ji, Changwei , Wang, Zhe , Wang, Shuofeng , Yang, Haowen , Wang, Huaiyu et al. Experimental investigation on the combustion characteristics of ultra-lean premixed hydrogen/air using turbulent jet ignition . | ENERGY , 2024 , 293 . |
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Abstract ：
Hydrogen can be used as fuel to replace gasoline, with the benefit of reducing harmful emissions of rotary engine (RE). The swirl chamber (SC) coupling spark plug and nozzle will achieve diffusion combustion and higher power as compared to the conventional spark plug. In the current work, a CFD model of a hydrogen-fueled rotary engine with swirl chamber (HFRE-SC) is established to study the impacts of hydrogen injection timing (HIT) and hydrogen injection duration (HID) on combustion characteristics of HFRE-SC. Results reveal that SC combustion system may achieve more combustion efficiency and higher indicated power when compared to port injection (PI). Moreover, lean hydrogen in the rear of combustion chamber (ROCC) can result from retarding HIT and extending HID. In addition, when the rich zone in SC moves toward the spark plug, making it difficult for flames to develop and spread. The best performance can be obtained when using the HIT at 75 degrees CA BTDC and the HID during 35 degrees CA, with an 8.42 % up in indicated power compared to the PI.
Keyword ：
Injection strategy Injection strategy Turbulent jet ignition Turbulent jet ignition Rotary engine Rotary engine Swirl chamber Swirl chamber Hydrogen Hydrogen
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| GB/T 7714 | Ji, Changwei , Wu, Shifan , Yi, Yue et al. Effects of hydrogen injection strategies on the flow field and combustion characteristics in a hydrogen-fueled rotary engine with the swirl chamber [J]. | FUEL , 2024 , 364 . |
| MLA | Ji, Changwei et al. "Effects of hydrogen injection strategies on the flow field and combustion characteristics in a hydrogen-fueled rotary engine with the swirl chamber" . | FUEL 364 (2024) . |
| APA | Ji, Changwei , Wu, Shifan , Yi, Yue , Yang, Jinxin , Wang, Haiyu , Meng, Hao et al. Effects of hydrogen injection strategies on the flow field and combustion characteristics in a hydrogen-fueled rotary engine with the swirl chamber . | FUEL , 2024 , 364 . |
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Abstract ：
There are few investigations on the knock characteristics of direct -injection (DI) hydrogen engines, so to reveal the influencing mechanism of synergistic effects of the deep Miller cycle and oxygen-enriched atmosphere on the DI hydrogen engine ' s knock characteristics, an experimental study was carried out at 1600 rpm and wide-open throttle conditions. Overall, the Miller effect provides good suppression of combustion knock even at high oxygen concentration ( phi O 2 ), while the oxygen-enriched atmosphere can mitigate the negative effects of the deep Miller cycle on the combustion process. The results demonstrated that the Miller cycle mitigates the excitation effect of elevated phi O 2 and reduced lambda on combustion knock. For example, even if phi O 2 was raised to 27.1 %, the knock intensity (KI) is only close to 1.0 bar at 1.6 lambda . It was found that the deep Miller cycle achieved by regulating the intake valve timing to the engine could further suppress the combustion knock, which may be related to the reduced effective compression ratio and volumetric efficiency. Specifically, under the deep Miller effect, KI did not exceed 0.8 bar even when phi O 2 was elevated to 32.0 %, indicating that knock was effectively suppressed, although about 190 cycles corresponding to knock durations exceeding 10 degrees CA.
Keyword ：
Deep Miller cycle Deep Miller cycle Knock Knock Hydrogen engine Hydrogen engine Oxygen-enriched atmosphere Oxygen-enriched atmosphere
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| GB/T 7714 | Hong, Chen , Xin, Gu , Xu, Song et al. An experimental study of knock in a DI hydrogen engine: The synergistic effects of the deep Miller cycle and oxygen-enriched atmosphere [J]. | ENERGY CONVERSION AND MANAGEMENT , 2024 , 306 . |
| MLA | Hong, Chen et al. "An experimental study of knock in a DI hydrogen engine: The synergistic effects of the deep Miller cycle and oxygen-enriched atmosphere" . | ENERGY CONVERSION AND MANAGEMENT 306 (2024) . |
| APA | Hong, Chen , Xin, Gu , Xu, Song , Cai, Jichun , Su, Fangxu , Wang, Shuofeng et al. An experimental study of knock in a DI hydrogen engine: The synergistic effects of the deep Miller cycle and oxygen-enriched atmosphere . | ENERGY CONVERSION AND MANAGEMENT , 2024 , 306 . |
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Abstract ：
Turbulent jet ignition (TJI) is an advanced ignition strategy that can improve the ignition and combustion characteristics of low-reactivity mixtures. The utilization of TJI system may be reliable to achieve the application of ammonia (NH3) internal combustion engines. Hydrogen (H2) is a potential auxiliary fuel for the pre-chamber, and the injection of a small amount of H2 in the pre-chamber is beneficial for promoting the ignition and combustion of NH3/air in the main chamber. In this study, the ignition and combustion characteristics of NH3/air adopting the active TJI with assisted H2 injection in pre-chamber were investigated, and the relevant experiments were conducted in the constant volume combustion bomb system. The results show that the H2 prechamber can improve the flammability of NH3/air, and properly increasing H2 injection is conducive to the rapid ignition of NH3/air in the main chamber. The turbulence introduced into the main chamber by the hot jet enhances the combustion process, and the generation of turbulence weakens the sensitivity of the combustion rate to the reactivity of the unburned mixture. The turbulence intensity can be increased by decreasing the prechamber orifice diameter, which increases the ignition delay but significantly shortens the combustion duration.
Keyword ：
Active pre -chamber Active pre -chamber Ammonia Ammonia Hydrogen Hydrogen Combustion characteristics Combustion characteristics Turbulence jet ignition Turbulence jet ignition
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| GB/T 7714 | Wang, Zhe , Ji, Changwei , Wang, Du et al. Analysis of the combustion characteristics of ammonia/air ignited by turbulent jet ignition with assisted hydrogen injection in pre-chamber [J]. | FUEL , 2024 , 367 . |
| MLA | Wang, Zhe et al. "Analysis of the combustion characteristics of ammonia/air ignited by turbulent jet ignition with assisted hydrogen injection in pre-chamber" . | FUEL 367 (2024) . |
| APA | Wang, Zhe , Ji, Changwei , Wang, Du , Zhang, Tianyue , Wang, Shuofeng , Wang, Huaiyu et al. Analysis of the combustion characteristics of ammonia/air ignited by turbulent jet ignition with assisted hydrogen injection in pre-chamber . | FUEL , 2024 , 367 . |
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Abstract ：
Turbulent jet ignition (TJI) is an advanced ignition mode that can enhance ignition and combustion performance, and it is a potential ignition strategy for ammonia/hydrogen internal combustion engines. This study aims to investigate the ignition and combustion characteristics of lean ammonia/hydrogen/air ignited by TJI, and the different ignition modes were compared. The results indicate that active TJI with auxiliary hydrogen injection in the pre-chamber improves the ignition and combustion performance of ammonia/hydrogen/air, and the appropriate shift of the pre-chamber equivalence ratio towards the rich side is considered optimal. As the ammonia fraction increases, the ignition mechanism in the main chamber changes from flame ignition to jet ignition. The advantage of TJI is mainly shown in high ammonia fraction mixtures, which is reflected in significantly lower ignition delay and combustion duration. In addition, TJI reduces the sensitivity of combustion to ammonia fraction compared to SI, due to the high ignition energy, initial flame area and turbulence provided by the hot jet. In TJI mode, the increase in jet velocity seems to be detrimental to the radial development of flames near the orifice, which may result in an increase in the duration of the final stage of combustion.
Keyword ：
Turbulent jet ignition Turbulent jet ignition Combustion characteristics Combustion characteristics Spark ignition Spark ignition Ammonia Ammonia Hydrogen Hydrogen
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| GB/T 7714 | Wang, Zhe , Zhang, Tianyue , Wang, Du et al. A comparative study on the premixed ammonia/hydrogen/air combustion with spark ignition and turbulent jet ignition [J]. | ENERGY , 2024 , 307 . |
| MLA | Wang, Zhe et al. "A comparative study on the premixed ammonia/hydrogen/air combustion with spark ignition and turbulent jet ignition" . | ENERGY 307 (2024) . |
| APA | Wang, Zhe , Zhang, Tianyue , Wang, Du , Wang, Shuofeng , Ji, Changwei , Wang, Huaiyu et al. A comparative study on the premixed ammonia/hydrogen/air combustion with spark ignition and turbulent jet ignition . | ENERGY , 2024 , 307 . |
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Abstract ：
This paper provides insights into the four key behaviors and mechanisms of the aging to failure of batteries in micro-overcharge cycles at different temperatures, as well as the changes in thermal stability. The test results from a scanning electron microscope (SEM) and an energy-dispersive spectrometer (EDS) indicate that battery failure is primarily associated with the rupture of cathode materials, the fracturing and pulverization of electrode materials on the anode current collector, and the formation of lithium dendrites. Additionally, battery safety is influenced by environmental temperatures and the battery's state of health (SOH), with failed batteries exhibiting the poorest stability and the highest mass loss rates. Under isothermal conditions, micro-overcharge leads to battery failure without thermal runaway. Thus, temperature stands out as the most influential factor in battery safety. These insights hold significant theoretical and practical value for the development of more precise and secure battery management systems.
Keyword ：
micro-overcharging micro-overcharging thermal runaway thermal runaway lithium-ion batteries lithium-ion batteries failure failure aging aging
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| GB/T 7714 | Zhang, Zhizu , Ji, Changwei , Wang, Yanan . Failure Mechanism and Thermal Runaway in Batteries during Micro-Overcharge Aging at Different Temperatures [J]. | MATERIALS , 2024 , 17 (9) . |
| MLA | Zhang, Zhizu et al. "Failure Mechanism and Thermal Runaway in Batteries during Micro-Overcharge Aging at Different Temperatures" . | MATERIALS 17 . 9 (2024) . |
| APA | Zhang, Zhizu , Ji, Changwei , Wang, Yanan . Failure Mechanism and Thermal Runaway in Batteries during Micro-Overcharge Aging at Different Temperatures . | MATERIALS , 2024 , 17 (9) . |
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Abstract ：
With the popularity of electric vehicles and climate change, it has become a typical scene to charge lithium -ion batteries (LIBs) at low temperatures at a high rate. Low temperature and high -rate charge and discharge would change the performance and then affect temperature rises, heat production and thermal runaway (TR) characteristics. This study tests the temperature rises of aging 18650 LIBs at various ambient temperatures and charge and discharge rates. The entropy and enthalpy changes of the batteries are computed based on the entropy coefficients, and subsequently, the heat productions of the batteries are computed. The TR test is carried out to explore the influence of rapid aging at low temperature environment on the thermal safety of LIBs. In this work, the heat generation mechanism and thermal runaway characteristics of lithium -ion batteries after lowtemperature and high -rate cyclic aging are introduced in detail, aiming to provide a reference for the process safe design and application of lithium -ion batteries at low -temperature and fast charging scenarios.
Keyword ：
Thermal runaway Thermal runaway Low -temperature Low -temperature Entropy Entropy Heat production Heat production Lithium -ion battery Lithium -ion battery
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| GB/T 7714 | Ji, Changwei , Liu, Dianqing , Liu, Yangyi et al. Effect of low temperature and high-rate cyclic aging on thermal characteristics and safety of lithium-ion batteries [J]. | PROCESS SAFETY AND ENVIRONMENTAL PROTECTION , 2024 , 188 : 1514-1526 . |
| MLA | Ji, Changwei et al. "Effect of low temperature and high-rate cyclic aging on thermal characteristics and safety of lithium-ion batteries" . | PROCESS SAFETY AND ENVIRONMENTAL PROTECTION 188 (2024) : 1514-1526 . |
| APA | Ji, Changwei , Liu, Dianqing , Liu, Yangyi , Wang, Shuofeng , Wang, Yanan , Zhang, Zhizu et al. Effect of low temperature and high-rate cyclic aging on thermal characteristics and safety of lithium-ion batteries . | PROCESS SAFETY AND ENVIRONMENTAL PROTECTION , 2024 , 188 , 1514-1526 . |
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Abstract ：
The flammability limits of the hydrogen-oxygen mixture are extremely wide, and the ignition energy is low. Due to its excellent combustion properties, the hydrogen-oxygen mixture can be used as fuel in internal combustion engines (ICEs). However, the combustion of hydrogen-oxygen mixture is too intense, which results in limited research on its application in ICEs and is limited to low-temperature conditions in aerospace. This research aims to numerically discuss the coupling effects of equivalence ratio and ignition timing on the port fuel injection hydrogen-oxygen ICE under the low-temperature intake condition. The three-dimensional geometric model of a single-cylinder ICE was established using the CONVERGE software and validated against the mean in-cylinder pressure and reaction mechanism. The results indicate that adjusting equivalence ratio and ignition timing operating parameters is beneficial for controlling the temperature and pressure in the cylinder within a reasonable range during the total combustion process. In general, under the low-temperature intake condition, adopting a high equivalence ratio and optimal ignition timing strategy improve the combustion process and power performance of the port fuel injection hydrogen-oxygen ICE.
Keyword ：
Port fuel injection Port fuel injection Hydrogen-oxygen internal combustion engine Hydrogen-oxygen internal combustion engine Combustion characteristics Combustion characteristics
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| GB/T 7714 | Ji, Changwei , Shen, Jianpu , Wang, Shuofeng . Numerical Investigation of Combustion Characteristics of the Port Fuel Injection Hydrogen-Oxygen Internal Combustion Engine Under the Low-Temperature Intake Condition [J]. | PROCEEDINGS OF THE 10TH HYDROGEN TECHNOLOGY CONVENTION, VOL 1, WHTC 2023 , 2024 , 393 : 25-34 . |
| MLA | Ji, Changwei et al. "Numerical Investigation of Combustion Characteristics of the Port Fuel Injection Hydrogen-Oxygen Internal Combustion Engine Under the Low-Temperature Intake Condition" . | PROCEEDINGS OF THE 10TH HYDROGEN TECHNOLOGY CONVENTION, VOL 1, WHTC 2023 393 (2024) : 25-34 . |
| APA | Ji, Changwei , Shen, Jianpu , Wang, Shuofeng . Numerical Investigation of Combustion Characteristics of the Port Fuel Injection Hydrogen-Oxygen Internal Combustion Engine Under the Low-Temperature Intake Condition . | PROCEEDINGS OF THE 10TH HYDROGEN TECHNOLOGY CONVENTION, VOL 1, WHTC 2023 , 2024 , 393 , 25-34 . |
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