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学者姓名：纪常伟
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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 ：
Adopting ammonia (NH3) is considered a viable way to reduce carbon emissions. The combustion of NH3/air can be enhanced through the fuel dissociation strategy and the use of turbulent jet ignition (TJI). This study investigated the combustion of partially dissociated NH3 ignited by active TJI. It can be found that the hydrogen (H2) pre-chamber effectively enhances the combustion of partially dissociated NH3, and the appropriate rich prechamber equivalence ratio is beneficial for the main chamber ignition. The lean main chamber mixtures realize the flame ignition mechanism and show a lower ignition delay. The increase in dissociation ratio enhances the tolerance of ignition to turbulence and leads to flame ignition mechanism. The increase in dissociation ratio also enhances the inhibiting effect of additional nitrogen (N2) on combustion, but the ignition mechanism and flame shape are not sensitive to the additional N2.
Keyword ：
Fuel dissociation Fuel dissociation Ignition characteristics Ignition characteristics Turbulent jet ignition Turbulent jet ignition Ammonia Ammonia Hydrogen Hydrogen
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| GB/T 7714 | Wang, Zhe , Zhang, Tianyue , Wang, Shuofeng et al. Combustion characteristics of NH3/H2/N2/air adopting the H2-assisted turbulent jet ignition [J]. | INTERNATIONAL JOURNAL OF HYDROGEN ENERGY , 2024 , 78 : 83-91 . |
| MLA | Wang, Zhe et al. "Combustion characteristics of NH3/H2/N2/air adopting the H2-assisted turbulent jet ignition" . | INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 78 (2024) : 83-91 . |
| APA | Wang, Zhe , Zhang, Tianyue , Wang, Shuofeng , Ji, Changwei . Combustion characteristics of NH3/H2/N2/air adopting the H2-assisted turbulent jet ignition . | INTERNATIONAL JOURNAL OF HYDROGEN ENERGY , 2024 , 78 , 83-91 . |
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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 explores the combustion and emission characteristics of TJI ammonia/hydrogen (NH3/H2) dual-fuel engines through experiments and numerical simulations. The NH3/H2 engine operates at 1600 rpm with a manifold absolute pressure of 60 kPa. Two independent hydrogen supply systems enable hydrogen port injection (HPI) and hydrogen direct injection (HDI). The results indicate that HDI yields higher power output compared to HPI. The strong injection ignition ability of the pre-chamber (PC) realizes the stable combustion of the NH3/H2 engine under different ammonia volume share (AVS) conditions. With the increase of AVS, the mixture of HDI in PC is stratified and the jet velocity is significantly reduced. Power output under HDI conditions decreases with increasing AVS. At an AVS of 10 %, the brake mean effective pressure (BMEP) and brake thermal efficiency (BTE) reach maximum values of 3.67 bar and 30.25 %, respectively. The BMEP and BTE increase and then decrease with increasing AVS under HPI conditions. An AVS of 40 % achieves peak power and efficiency. The CA10-90 is always shorter than CA0-10 in the combustion process. At an AVS of 20 %, NO emissions peak and then decrease with increasing AVS, but higher AVS increases unburned NH3 and N2O. Experimental results show that spark timing (ST) has relatively low sensitivity to H2-dominated TJI NH3/H2 combustion. With the increase of AVS to 60 %, the delayed ST will lead to a rapid decrease in power output and a sharp deterioration in combustion stability. When the ST is postponed from 12 degrees CA BTDC to 4 degrees CA ATDC, and AVS is 60 %, the COVPmax of the TJI engine increases rapidly from 1.9 % to 13.9 %.
Keyword ：
Turbulent jet ignition Turbulent jet ignition Emission Emission Ammonia-hydrogen engine Ammonia-hydrogen engine Spark timing Spark timing Passive pre-chamber Passive pre-chamber
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| GB/T 7714 | Qiang, Yanfei , Zhao, Shihao , Su, Fangxu et al. Experimental and numerical assessment on co-combustion of hydrogen with ammonia in passive pre-chamber engines [J]. | APPLIED THERMAL ENGINEERING , 2024 , 259 . |
| MLA | Qiang, Yanfei et al. "Experimental and numerical assessment on co-combustion of hydrogen with ammonia in passive pre-chamber engines" . | APPLIED THERMAL ENGINEERING 259 (2024) . |
| APA | Qiang, Yanfei , Zhao, Shihao , Su, Fangxu , Wang, Fuzhi , Yang, Jinxin , Wang, Shuofeng et al. Experimental and numerical assessment on co-combustion of hydrogen with ammonia in passive pre-chamber engines . | APPLIED THERMAL ENGINEERING , 2024 , 259 . |
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Abstract ：
Ammonia (NH3) is a potential alternative fuel for internal combustion engines, but the disadvantages of low combustion intensity and high nitrogen oxides should be addressed to achieve its application. For NH3 mixture, fuel -rich combustion is a potential method to reduce NOx emissions, and the utilization of turbulent jet ignition (TJI) can enhance its ignition and combustion. Therefore, a strategy of using TJI with assisted oxygen (O2) injection in the pre -chamber to ignite rich NH3/air mixtures was proposed in this study. Considering the lack of relevant research, a fundamental investigation was conducted in this work. The results indicate that the provided method can effectively promote the combustion of NH3/air. The pre -chamber equivalence ratio has no significant effect on the jet strength, but more excess injected O2 enhances the ignition performance of the unburned mixture in the main chamber. The increase of the main chamber equivalence ratio and the decrease of the orifice diameter will result in a higher jet velocity. The ignition of NH3/air is the result of turbulence competing with the reactivity of the mixture. Therefore, high jet velocity leads to poor ignition performance due to the low reactivity of NH3, but appropriate turbulence intensity can promote rapid combustion.
Keyword ：
Turbulent jet ignition Turbulent jet ignition Ammonia Ammonia Combustion characteristic Combustion characteristic Fuel -rich combustion Fuel -rich combustion Oxygen Oxygen
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| GB/T 7714 | Wang, Zhe , Ji, Changwei , Wang, Du et al. Experimental investigation on combustion characteristics of ammonia/air using turbulent jet ignition with auxiliary oxygen in pre-chamber [J]. | APPLIED THERMAL ENGINEERING , 2024 , 243 . |
| MLA | Wang, Zhe et al. "Experimental investigation on combustion characteristics of ammonia/air using turbulent jet ignition with auxiliary oxygen in pre-chamber" . | APPLIED THERMAL ENGINEERING 243 (2024) . |
| APA | Wang, Zhe , Ji, Changwei , Wang, Du , Zhang, Tianyue , Wang, Shuofeng , Yang, Haowen et al. Experimental investigation on combustion characteristics of ammonia/air using turbulent jet ignition with auxiliary oxygen in pre-chamber . | APPLIED THERMAL ENGINEERING , 2024 , 243 . |
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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 ：
This paper aims to numerically investigate the effects of high compression ratio (CR) on the performance of ammonia-hydrogen engines. In this work, four CRs from 10.7 to 13.7 with scanning spark timing (ST) from 28(degrees)CA to 0(degrees)CA BTDC were analyzed. The main results are as follows: As the CR increases, there is a trade-off relationship between the dissipation rate of turbulence and the turbulent kinetic energy (TICE). Initially, the TICE rises as the CR increases. As the CR continues to rise, the tendency for an increase in TICE diminishes, while the turbulent dissipation rate consistently rises. Additionally, there is an escalation in heat transfer loss. Therefore, there is a trend of rising and then falling in the flow velocity and turbulence intensity with the increase of the CR. Ammonia-hydrogen flame propagation is susceptible to temperature and flow field, and a high CR can improve ignition stability, shorten combustion duration, minimize cooling loss, and enhance output power. Unfortunately, the emission of NOx gradually rises as the CR increases. At high CR, the combustion performance is optimized by adjusting ST, and the maximum IMEP and ITE are 4 bar and 38.3 %, respectively. The ST for maximum braking torque (MBT) should be gradually delayed toward TDC as the CR increases.
Keyword ：
Spark-ignition timing Spark-ignition timing Ammonia Ammonia SI engine SI engine Compression ratio Compression ratio Combustion Combustion Hydrogen Hydrogen
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| GB/T 7714 | Ji, Changwei , Qiang, Yanfei , Wang, Shuofeng et al. Numerical investigation on the combustion performance of ammonia-hydrogen spark-ignition engine under various high compression ratios and different spark-ignition timings [J]. | INTERNATIONAL JOURNAL OF HYDROGEN ENERGY , 2024 , 56 : 817-827 . |
| MLA | Ji, Changwei et al. "Numerical investigation on the combustion performance of ammonia-hydrogen spark-ignition engine under various high compression ratios and different spark-ignition timings" . | INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 56 (2024) : 817-827 . |
| APA | Ji, Changwei , Qiang, Yanfei , Wang, Shuofeng , Xin, Gu , Wang, Zhe , Hong, Chen et al. Numerical investigation on the combustion performance of ammonia-hydrogen spark-ignition engine under various high compression ratios and different spark-ignition timings . | INTERNATIONAL JOURNAL OF HYDROGEN ENERGY , 2024 , 56 , 817-827 . |
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Abstract ：
To reduce carbon emissions, the application of hydrogen as a zero-carbon fuel in the field of internal combustion engines (ICEs) has become a hot topic in recent years. Meanwhile, the application of ignition methods such as turbulent jet ignition (TJI) in engines has been gradually attracting the interest of numerous scholars. However, there is a lack of research on the performance of the hydrogen-fueled engine with passive pre-chamber (PPC). This paper aims to explore the combustion and emission performance of TJI hydrogen engines under different load conditions through experimental and numerical methods. This study is based on a Miller cycle engine equipped with the PPC, where hydrogen is injected directly into the cylinder. The operational characteristics of internal flow field characteristics, combustion, and energy conversion in the PPC are revealed by numerical. The engine operates at a speed of 1600 rpm and an excess air ratio (lambda) of 1.8. The results show that at a manifold absolute pressure (MAP) of 40 kPa, the brake mean effective pressure (BMEP) is 0.95 bar, and the brake thermal efficiency (BTE) is 17.26 %, with the coefficient of variation (COV) of the indicated mean effective pressure (COVIMEP) of 3.3 %. Although BMEP can be increased to 5.3 bar, BTE is 40.3 %, and COVIMEP can be reduced to 1.1 % under WOT, emissions have significantly increased. Additionally, the study explores the effect of variable valve timing (VVT) and spark timing (ST) on the performance of the hydrogen engine with PPC under partial load conditions. The results indicate that the ST has an insignificant influence on the power performance of TJI hydrogen engines, but delaying the ST could reduce nitrogen oxide (NOx) emissions. By appropriately delaying the timing of the intake valve opening (IVO), not only the power performance of TJI hydrogen engines could be improved, but also the COVIMEP could be reduced.
Keyword ：
Load Load Passive pre -chamber ignition Passive pre -chamber ignition Variable valve timing Variable valve timing Hydrogen Hydrogen Combustion analysis Combustion analysis
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| GB/T 7714 | Qiang, Yanfei , Ji, Changwei , Wang, Shuofeng et al. Study on the effect of variable valve timing and spark timing on the performance of the hydrogen-fueled engine with passive pre-chamber ignition under partial load conditions [J]. | ENERGY CONVERSION AND MANAGEMENT , 2024 , 302 . |
| MLA | Qiang, Yanfei et al. "Study on the effect of variable valve timing and spark timing on the performance of the hydrogen-fueled engine with passive pre-chamber ignition under partial load conditions" . | ENERGY CONVERSION AND MANAGEMENT 302 (2024) . |
| APA | Qiang, Yanfei , Ji, Changwei , Wang, Shuofeng , Xin, Gu , Hong, Chen , Wang, Zhe et al. Study on the effect of variable valve timing and spark timing on the performance of the hydrogen-fueled engine with passive pre-chamber ignition under partial load conditions . | ENERGY CONVERSION AND MANAGEMENT , 2024 , 302 . |
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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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