This page has only limited features, please log in for full access.

Unclaimed
Dai Liu
College of Power and Energy Engineering, Harbin Engineering University, Harbin, China

Basic Info

Basic Info is private.

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Journal article
Published: 16 June 2021 in Mechanical Systems and Signal Processing
Reads 0
Downloads 0

In order to improve the energy efficiency and suppress the environmental pollutants of marine diesel engines, analysis and control of combustion phases including late combustion phase and premixed combustion phase are considered as an attractive potential strategy. Consequently, it is necessary to accurately identify the combustion parameters that are representative to these combustion phases, such as start of combustion (SOC), start of diffusive combustion (SODC) and start of late combustion (SOLC). The real-time analysis of the combustion phases can be further applied for closed-loop combustion control (CLCC). However, the existing methods can’t guarantee the accurate detection of combustion parameters simultaneously even though high computational resources are invested. In this study, the resonance excitation of in-cylinder pressure was found to be capable for identifying all of the three combustion phases parameters. Hence, several effective signal processing techniques were proposed to detect these combustion phases parameters from resonant pressure signal. Without complex mathematic algorithms, the proposed method shows high potential for CLCC since it is relatively easier and faster to achieve than other existing techniques. The accuracy of this method was validated by experimental heat release rate and in-cylinder temperature. Furthermore, based on combustion phase parameters obtained, the estimations of combustion state and energy efficiency were discussed. Finally, this method was also applied for combustion phase detection in another type of marine diesel engine, which verified the robustness of this method.

ACS Style

Long Liu; Ximing Chen; Dai Liu; Jingtao Du; Wanyou Li. Combustion phase identification for closed-loop combustion control by resonance excitation in marine diesel engines. Mechanical Systems and Signal Processing 2021, 163, 108115 .

AMA Style

Long Liu, Ximing Chen, Dai Liu, Jingtao Du, Wanyou Li. Combustion phase identification for closed-loop combustion control by resonance excitation in marine diesel engines. Mechanical Systems and Signal Processing. 2021; 163 ():108115.

Chicago/Turabian Style

Long Liu; Ximing Chen; Dai Liu; Jingtao Du; Wanyou Li. 2021. "Combustion phase identification for closed-loop combustion control by resonance excitation in marine diesel engines." Mechanical Systems and Signal Processing 163, no. : 108115.

Research article
Published: 09 February 2021 in E3S Web of Conferences
Reads 0
Downloads 0

Multi-injector system is potential to improve thermal efficiency and NOx emission of diesel engine at the same time. In order to optimize the combustion and emission of Marine medium speed diesel engine, the engine combustion with a multi-injector system is simulated and analyzed by CFD software Converge. In this research, two injectors are installed at the side of the cylinder head while the central injector is maintained. Various injection directions of side injectors and injection strategies of multi-injector system are simulated to optimize the fuel spray and combustion. The analysis results show that the spray angle of the side injector plays a key role for effective thermal efficiency improvement, since complex spray jet-jet interaction and spray impingement may deteriorate the combustion if the arrangement of spray angle was not set properly. Once the fuel injection direction has been optimized, the fuel ratio of the three injectors is optimized and improved the effective thermal efficiency with lower NOx emission. The results show that the two side injectors could increase the fuel injection rate into the cylinder, leading to high brake power and consequently increased the thermal efficiency by 1.26% and decreased the NOx emission by 16% for the best optimization.

ACS Style

Dai Liu; Yingzhu Guo; Long Liu; Qian Xia; Yong Gui. Optimization of Marine Medium Speed Diesel Engine Performance based on Multi-Injector System. E3S Web of Conferences 2021, 236, 01026 .

AMA Style

Dai Liu, Yingzhu Guo, Long Liu, Qian Xia, Yong Gui. Optimization of Marine Medium Speed Diesel Engine Performance based on Multi-Injector System. E3S Web of Conferences. 2021; 236 ():01026.

Chicago/Turabian Style

Dai Liu; Yingzhu Guo; Long Liu; Qian Xia; Yong Gui. 2021. "Optimization of Marine Medium Speed Diesel Engine Performance based on Multi-Injector System." E3S Web of Conferences 236, no. : 01026.

Journal article
Published: 20 July 2020 in Applied Sciences
Reads 0
Downloads 0

In diesel engines, fuel mixing is an important process in determining the combustion efficiency and emissions level. One of the measures used to achieve fuel mixing is controlling the nature and behavior of the fuel spray by shaping the injection rate. The mechanism underlying the behavior of the spray with varying injection rates before the start of combustion is not fully understood. Therefore, in this research, the fuel injection rate shape is investigated to assess the spraying and mixing behavior. Diesel sprays with different ambient temperatures and injection pressures are modeled using the CONVERGE-CFD software. The validation is performed based on experimental data from an Engine Combustion Network (ECN). The verified models are then used to analyze the characteristics of the diesel spray before and after the end-of-injection (EOI) with four fuel injection rate shapes, including a rectangular injection rate shape (RECT), a quick increase gradual decrease injection rate shape (QIGD), a gradual increase gradual decrease injection rate shape (GIGD), and a gradual increase quick decrease injection rate shape (GIQD). The spray vapor penetrations, liquid lengths, evaporation ratios, Sauter mean diameter (SMDs), distributions of turbulence kinetic energy, temperatures, and equivalence ratios were compared under different injection rate shapes. The results show that the QIGD injection rate shape can enhance mixing during injection, while the GIQD injection rate shape can achieve better mixing after the EOI.

ACS Style

Intarat Naruemon; Long Liu; Dai Liu; Xiuzhen Ma; Keiya Nishida. An Analysis on the Effects of the Fuel Injection Rate Shape of the Diesel Spray Mixing Process Using a Numerical Simulation. Applied Sciences 2020, 10, 4983 .

AMA Style

Intarat Naruemon, Long Liu, Dai Liu, Xiuzhen Ma, Keiya Nishida. An Analysis on the Effects of the Fuel Injection Rate Shape of the Diesel Spray Mixing Process Using a Numerical Simulation. Applied Sciences. 2020; 10 (14):4983.

Chicago/Turabian Style

Intarat Naruemon; Long Liu; Dai Liu; Xiuzhen Ma; Keiya Nishida. 2020. "An Analysis on the Effects of the Fuel Injection Rate Shape of the Diesel Spray Mixing Process Using a Numerical Simulation." Applied Sciences 10, no. 14: 4983.

Journal article
Published: 07 May 2019 in Applied Sciences
Reads 0
Downloads 0

Pilot injection combined with exhaust gas recirculation (EGR) is usually utilized to realize the partially premixed compression ignition (PPCI) mode in diesel engines, which enables the simultaneous decrease of nitrogen oxide and soot emissions to satisfy emission regulations. Moreover, the ignition delay of main injection combustion can also be shortened by pilot injection, and then combustion noise is reduced. Nevertheless, the mechanisms of pilot injection impacts on combustion noise are not completely understood. As such, it is hard to optimize pilot injection parameters to minimize combustion noise. Therefore, experiments were conducted on a four-stroke single-cylinder diesel engine with different pilot injection strategies and 20% EGR as part of an investigation into this relationship. Firstly, the combustion noise was analyzed by cylinder pressure levels (CPLs). Then, the stationary wavelet transforms (SWTs) and stationary wavelet packet transform (SWPT) were employed to decompose in-cylinder pressures at different scales, and thus the combustion noise generated by pilot and main combustion was investigated in both the time and frequency domain. The results show that pilot injection is dominant in the high frequency segment of combustion noise, and main injection has a major impact on combustion noise in the low and mid frequency segment. Finally, the effects of various pilot injection parameters on suppressing combustion noise were analyzed in detail.

ACS Style

Jingtao Du; Ximing Chen; Long Liu; Dai Liu; Xiuzhen Ma. Mechanism of Combustion Noise Influenced by Pilot Injection in PPCI Diesel Engines. Applied Sciences 2019, 9, 1875 .

AMA Style

Jingtao Du, Ximing Chen, Long Liu, Dai Liu, Xiuzhen Ma. Mechanism of Combustion Noise Influenced by Pilot Injection in PPCI Diesel Engines. Applied Sciences. 2019; 9 (9):1875.

Chicago/Turabian Style

Jingtao Du; Ximing Chen; Long Liu; Dai Liu; Xiuzhen Ma. 2019. "Mechanism of Combustion Noise Influenced by Pilot Injection in PPCI Diesel Engines." Applied Sciences 9, no. 9: 1875.