Xiangyu Meng

• 中国政法大学

Blending ammonia (NH3) with hydrogen (H2) in the spark ignition (SI) mode and adding H2 to the pre-chamber in turbulent jet ignition (TJI) mode effectively extend the lean limit and enhance the stability of ammonia combustion. This study developed and validated SI and TJI numerical models through visualization experiments, employing an isotope labe...

Methanol (CH3OH) blended with ammonia (NH3) cracked gas offers the potential for efficient combustion, while the use of a carbon dioxide (CO2) enriched exhaust gas recirculation (EGR) system effectively reduces NOx emissions. Investigating the flame instability of this blended fuel is crucial for ensuring efficient and safe combustion. In this stud...

Pre-chamber enrichment for igniting ultra-lean premixed H 2 /air is an effective strategy for achieving ultra-low emission and improved fuel economy. This study employed a three-dimensional numerical simulation based on a constant volume combustion chamber to investigate jet ignition characteristics under varying main and pre-chamber equivalence ra...

Synergistic effects of carbon dioxide (CO2) and hydrogen (H2) can improve the combustion and emissions characteristics of ammonia (NH3)/methane (CH4) blends. This study experimentally and kinetically investigates the interaction effects between CO2 dilution and H2 addition on flame propagation and instability mechanisms of NH3/CH4 blends at high te...

Dimethyl ether (DME) steam reforming (SR) and cracking (CR) can produce H2 and CH4 to improve laminar burning velocity (LBV) of ammonia (NH3). In this study, a mechanism was updated to simulate the combustion of NH3, DME, H2, CH4, CO and their blends with the comprehensive validations of LBV and emissions. Three types of SR and one type of CR with...

Dimethyl ether (DME) steam reforming (SR) and cracking (CR) can not only achieve on-line production of hydrogen (H2) and methane (CH4) but also increase fuel energy. The ammonia blending with DME-SR or DME-CR gases is an effective method to enhance the reactivity of ammonia combustion. This paper aims to compare the effects of DME-SR and DME-CR on...

Ammonia (NH3) on-line cracking to produce hydrogen (H2) can avoid direct ammonia combustion and is an important method to enhance combustion performance and control nitrogen oxide (NOx) emissions. This work aims to study the effects of various ammonia energy ratios (ENH3) and cracking ratios (CNH3) on the combustion and NO emission characteristics...

Ammonia (NH3), as an ideal zero-carbon fuel, plays a positive role in mitigating global warming. By cofiring NH3 with highly reactive small molecule fuels such as hydrogen (H2), carbon monoxide (CO) and methane (CH4), the reactivity of NH3 combustion can be significantly enhanced. In this work, a detailed kinetic mechanism for NH3/CH4/H2/CO contain...

Ammonia, as a carbon-free alternative fuel, has attracted a lot of attention. However, ammonia has slow laminar burning velocity and high ignition energy and NOx emissions. The ignition chamber has been proven to greatly enhance ignition energy. Methanol, as a low-carbon liquid fuel with a low evaporation temperature (64.5 °C), is easy to store and...

As a favorable hydrogen carrier, ammonia (NH3) has great potential to achieve the goal of carbon neutrality in engines. However, it has several limits on the combustion in engines such as low laminar burning velocity (LBV), high ignition energy, and high nitrogen oxide (NOx) emission. It needs to employ an appropriate method for its utilization in...

Ammonia (NH3) has been supposed to be the potential alternative energy source towards carbon neutrality. However, it has several unfavorable combustion characteristics, such as the slow combustion rate, poor combustion stability, high ignition energy and so on. As a renewable fuel, dimethyl ether (DME) is also considered to be a favorable carbon–ne...

A variable valvetrain system is the key part of the variable stroke engine (VSE), which could achieve higher power performance and low-speed torque. An innovative axial shift valvetrain system (ASVS) was put forward to meet the air-charging requirements of a 2/4-stroke engine and complete a changeover within one working cycle. Two sets of intake an...

To extend the load range of premixed combustion, the jet controlled compression ignition (JCCI) mode with dual-direct injectors was adopted in a high-speed light-duty diesel engine. The pre-mixture was flexibly prepared by the direct pre-injection of blended fuels, and the ignition timing could be controlled robustly by the diesel jet-injection. En...

High-pressure air (HPA) jet controlled compression ignition (JCCI) accomplished in the hybrid pneumatic engine (HPE) was studied in the work. Based on the compound thermodynamic cycle in HPE, it reveals the intensified low-temperature reaction and two-stage high-temperature reaction caused by the high-pressure air jet. The high-pressure air jet com...

A novel method called high-pressure air (HPA) jet controlled compression ignition (JCCI) based on the compound thermodynamic cycle was investigated in this work. The combustion process of premixed mixture can be controlled flexibly by the high-pressure air jet compression, and it characterizes the intensified low-temperature reaction and two-stage...

Compressed natural gas (CNG) enrichment ignited by the diesel fuel in the compression ignition engine generally reveals low thermal efficiency and high carbon monoxide (CO) and total hydrocarbons (THC) emissions at low load due to the over-lean mixture. This paper aims to numerically study the improvement effectiveness of throttling on the efficien...

Dual-fuel combustion using diesel and high-octane number (ON) biofuel of n-butanol blends to ignite compressed natural gas (CNG) with pilot fuel split injection was investigated. 30% n-butanol/70% diesel (B30D70) and pure diesel (B0D100) as the pilot fuels were compared with the start of pre-injection (SOIp) timings swept from −30 (SOIp30) to −80 °...

Braking safety of heavy-duty engines has always been the focus of the research, and the fuel economy and after-treatment thermal management during low-load operation of heavy-duty engines have also received much attention in recent years. A variable mode valve actuation system which can realize switching between four-stroke driving, two-stroke comp...

A new variable mode valve actuation system for a heavy-duty engine was proposed and designed in this paper. The variable mode valve actuation system can significantly enhance braking safety and improve fuel economy and emission of heavy-duty engines through flexible switching among four-stroke driving mode, two-stroke compression-release braking mo...

In order to enhance the braking safety and improve the fuel economy and emission of heavy-duty engines, a variable mode valve actuation system which can switch operation modes flexibly among four-stroke driving, two-stroke compression release braking, and cylinder deactivation modes on a four-stroke engine was developed in this article. The switchi...

As the pilot fuel property and equivalence ratio of the mixture exhibit significant effect on the combustion and emission characteristics in the dual-fuel operation mode with compressed natural gas (CNG), in this work, bio-fuel of n-butanol as the additive in diesel in conjunction with boost air intake pressure (Pin) was studied at indicated mean e...

To figure out the interaction between direct-injected methanol and diesel during the whole combustion process, this paper studied the direct-injected methanol ignited by diesel through shadowgraph and natural luminescence imaging in a constant volume combustion chamber which allows both fuels directly injected with high pressure. Strategies of dies...

To improve the performance and emission characteristics in the diesel/CNG dual-fuel combustion mode, bio-fuel of n-butanol as the additive in the pilot fuel was investigated by sweeping a wide range of CNG substitution rates. The experiments were conducted at fixed CA50s of 4.5 and 5.5 °CA ATDC for approximately 5 bar IMEP (low load) and 7.5 bar IM...

In this work, diesel-n-butanol blends as the pilot fuel were studied to explore the possibility of improving the performance and emissions in the dual-fuel combustion mode with CNG, and the trade-offs among NO x , THC and CO were also discussed. The pilot fuels including B0 (pure diesel), B10 (90% diesel/10% n-butanol)and B20 (80% diesel/20% n-buta...

Fuel Jet Controlled Compression Ignition (JCCI) was proposed to control the combustion phasing of premixed charge. In this mode, a small quantity of jet-injection diesel fuel was used to ignite the premixed charge, which was prepared by the main pre-injection blended fuels of diesel and ethanol-gasoline. Experiments of JCCI mode combined with dual-...

Because of the potential to reduce NOx and PM emissions simultaneously and the utilization of biofuel, diesel/compressed natural gas (CNG) dual-fuel combustion mode with port injection of CNG and direct injection of diesel has been widely studied. While in comparison with conventional diesel combustion mode, the dual-fuel combustion mode generally...

Acetone is widely recognized as a major organic solvent and also a basic ingredient for varnishes and paints. In comparison with ethanol, acetone has more attractive properties as a potential alternative fuel such as its higher energy density, heating value, and volatility. However, the water content in acetone production would lead to a high cost...

The physico-chemical characterization of exhaust soot is very important in the design and operation of suitable after-treatment systems. The nanostructure and reactivity of soot depends strongly on the initial fuel identity and synthesis conditions. This paper presents the chemical composition, oxidation reactivity and nanostructural characteristic...

The high-pressure air jet controlled compression ignition (JCCI) combustion mode was employed to control the premixed diesel compression ignition combustion phasing by using the compound thermodynamic cycle under all operating conditions, which is accomplished in a hybrid pneumatic engine (HPE). A three-dimensional computational fluid dynamics (CFD...

This paper presents the chemical composition, oxidation reactivity and nanostructural characteristics of particulate matter (PM) produced by a diesel engine operating with diesel/compressed natural gas (CNG) dual-fuel combustion. Raw, undiluted soot samples from pure diesel, 40% CNG, and 70% CNG (energy-based substitution rate) combustion were coll...

Dual-fuel combustion mode with direct injection of diesel as the pilot fuel and port injection of compressed natural gas (CNG) in compression ignition (CI) engines has been widely investigated to comply with the latest emission regulations. The diesel-CNG dual-fuel combustion mode shows some potential to decrease NOx and soot emissions simultaneous...

The use of natural gas in compression ignition engines as a supplement to diesel under dual-fuel combustion mode is a promising technique to increase efficiency and reduce emissions. In this study, the effect of dual-fuel operating mode on combustion characteristics, engine performance and pollutant emissions of a diesel engine using natural gas as...

To control premixed charge compression ignition (PCCI) phasing in internal combustion engines, a novel method called high-pressure air jet controlled compression ignition (JCCI) based on compound thermodynamic cycle was proposed to achieve diesel premixed combustion in all load operations. The method is implemented in a hybrid pneumatic engine (HPE...

The use of natural gas in compression ignition engines as a supplement to diesel under dual-fuel combustion mode is a promising technique to increase efficiency and reduce emissions. In this study, the effect of dual-fuel operating mode on combustion characteristics, engine performance and pollutant emissions of a diesel engine using natural gas as...

To directly control the premixed combustion phasing, a novel method called Jet Controlled Compression Ignition (JCCI) is investigated. Experiments were conducted on a single cylinder natural aspirated diesel engine at 3000 r/min without EGR. Numerical model was validated by pressure and heat release rate curves at a fixed spark timing. The simulati...

In order to directly control the premixed combustion phasing, a Jet Controlled Compression Ignition (JCCI) for diesel premixed compression ignition systems is investigated. Experiments were conducted on a single cylinder natural aspirated diesel engine without EGR at 3000 rpm. Numerical models were validated by load sweep experiments at fixed spark...