The Combustion Process in a DI Diesel Hydraulic Free Piston Engine

1996 ◽  
Author(s):  
Joop H. E. Somhorst ◽  
Peter A. J. Achten
Keyword(s):  
Combustion Process ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

scholarly journals Research on the Operating Characteristics of Hydraulic Free-Piston Engines: A Systematic Review and Meta-Analysis

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3530
Author(s):  
Fukang Ma ◽  
Shuanlu Zhang ◽  
Zhenfeng Zhao ◽  
Yifang Wang
Keyword(s):  
Systematic Review ◽  
High Efficiency ◽  
Meta Analysis ◽  
Combustion Process ◽  
Research Progress ◽  
Future Research ◽  
Operating Characteristics ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

The hydraulic free-piston engine (HFPE) is a kind of hybrid-powered machine which combines the reciprocating piston-type internal combustion engine and the plunger pump as a whole. In recent years, the HFPE has been investigated by a number of research groups worldwide due to its potential advantages of high efficiency, energy savings, reduced emissions and multi-fuel operation. Therefore, our study aimed to assess the operating characteristics, core questions and research progress of HFPEs via a systematic review and meta-analysis. We included operational control, starting characteristics, misfire characteristics, in-cylinder working processes and operating stability. We conducted the literature search using electronic databases. The research on HFPEs has mainly concentrated on four kinds of free-piston engine, according to piston arrangement form: single piston, dual pistons, opposed pistons and four-cylinder complex configuration. HFPE research in China is mainly conducted in Zhejiang University, Tianjin University, Jilin University and the Beijing Institute of Technology. In addition, in China, research has mainly focused on the in-cylinder combustion process while a piston is free by considering in-cylinder combustion machinery and piston dynamics. Regarding future research, it is very important that we solve the instabilities brought about by chance fluctuations in the combustion process, which will involve the hydraulic system’s efficiency, the cyclical variation, the method of predicting instability and the recovery after instability.

Multi-Dimensional Analysis of NOx and Soot Formation in a Diesel-Fueled Hydraulic Free Piston Engine

2013 ◽  
Vol 690-693 ◽  
pp. 2800-2804
Author(s):  
Ying Xiao Yu ◽  
Zhao Cheng Yuan ◽  
Jia Yi Ma ◽  
Shi Yu Li
Keyword(s):  
Mass Fraction ◽  
Soot Formation ◽  
Combustion Process ◽  
Injection Timing ◽  
Swirl Ratio ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Minor Influence ◽  
A Minor

This paper is aimed at simulating and analyzing emission NOxand Soot formation in the hydraulic free piston engine (HFPE) designed and constructed by Jilin University. The combustion process of HFPE is simulated by using the commercial CFD software AVL FIRE, and the flow field and factors that influence NOxand Soot formation were analyzed. The simulated results indicate that NO is mainly distributed in the burned zone, whereas the distribution of Soot acts in accord with high unburnt equivalence ratio and high temperature burned zone. Injection timing increases, the amount of the formation of NO is reduced, whereas the mass fraction of Soot rises to a peak and descends. And small swirl ratio exerts a minor influence on emission mass fraction of HFPE.

Experimental investigation of the cycle-to-cycle variations in combustion process of a hydraulic free-piston engine

Energy ◽  
2014 ◽  
Vol 78 ◽  
pp. 257-265 ◽  
Author(s):  
Zhenfeng Zhao ◽  
Dan Wu ◽  
Zhenyu Zhang ◽  
Fujun Zhang ◽  
Changlu Zhao
Keyword(s):  
Experimental Investigation ◽  
Combustion Process ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

Effect of Piston Motion on Combustion of CNG Free Piston Engine (FPE)

2014 ◽  
Vol 889-890 ◽  
pp. 501-506
Author(s):  
Ning Xia Yin ◽  
Zhao Ping Xu ◽  
Si Qin Chang ◽  
Ji Ming Lin
Keyword(s):  
Heat Transfer ◽  
Combustion Process ◽  
Engine Performance ◽  
Expansion Ratio ◽  
Nox Emissions ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
Beneficial Effects ◽  
Free Piston Engine

CNG is thought to be one of the most promising alternatives to traditional fuels. The multi-fuel ability is another characteristic of the FPE. The piston motion can be controlled to have beneficial effects on the engine performance. This article investigates the effect of piston motion on combustion of four-stroke CNG FPE using a multidimensional simulation model. It is found that the high piston acceleration and velocity at top dead center increases expansion ratio and fasting combustion, reduces the heat transfer losses and decreased NOx emissions formation. At the same time, the turbulent kinetic energy of the gas during the combustion process is added.

Modeling of Piston Trajectory-Based HCCI Combustion

2014 ◽  
Author(s):  
Chen Zhang ◽  
Ke Li ◽  
Zongxuan Sun
Keyword(s):  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Combustion Process ◽  
Gas Temperature ◽  
Piston Engine ◽  
Free Piston ◽  
Active Motion ◽  
Motion Patterns ◽  
Bottom Dead Center ◽  
Free Piston Engine

Previously, the authors have designed and implemented an active motion control “virtual crankshaft” for a free piston engine, which enables precise piston tracking of desired trajectories. With this mechanism, the volume of the combustion chamber can be regulated, and therefore the pressure, temperature and species concentrations of in-cylinder gas can be adjusted in real-time which affect the combustion process directly. This new degree of freedom enables us to conduct trajectory-based combustion control. In this paper, a model of the free piston engine running homogeneous charge compression ignition combustion under variant piston trajectories is presented. The variant piston trajectories have the ability to change the compression ratio and accommodate different piston motion patterns between the top dead center and the bottom dead center. The Lawrence Livermore National Laboratory reduced n-heptane reaction mechanism is employed in the model in order to describe the chemical kinetics under various piston trajectories. Analysis of the simulation results is then presented which reveals the piston trajectory effects on the combustion phenomena in terms of in-cylinder gas temperature trace, indicated output work, heat loss and radical species accumulation process.

Research of Micro Free-Piston Engine Generator Performance

2011 ◽  
Vol 199-200 ◽  
pp. 198-202
Author(s):  
Qian Wang ◽  
Jin Hua Yang ◽  
Jin Bai ◽  
Jun Jie Chen ◽  
Ze Chen
Keyword(s):  
Dynamic Model ◽  
Combustion Process ◽  
Engine Performance ◽  
Combustion Efficiency ◽  
Operating Characteristics ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Engine Combustion ◽  
Ignition And Combustion

Based on the operating characteristics of a micro HCCI (Homogeneous Charge Compress Ignition) free-piston engine, a multidimensional model which coupled CFD code, chemical dynamic model and piston dynamic model has been established. Using this model, an ignition and combustion process of the micro engine is simulated, the cylinder pressure and temperature profiles are obtained, and the influence of leakage and heat lost on micro engine combustion process is analyzed. Meanwhile, working characteristics of micro engine generator are evaluated by employing the simulation result. Power, combustion efficiency, etc of the micro engine are obtained. Lastly, the micro engine working characteristics with different load, fuel and piston mass are compared and effects of those varying conditions on engine performance are investigated. Simulation result provides essential requirements for micro free-piston engine control and design.

scholarly journals Effects of Injector Spray Angle on Performance of an Opposed-Piston Free-Piston Engine

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3735
Author(s):  
Qinglin Zhang ◽  
Zhaoping Xu ◽  
Shuangshuang Liu ◽  
Liang Liu
Keyword(s):  
Combustion Engine ◽  
Fluid Dynamic ◽  
Combustion Process ◽  
Three Dimensional ◽  
Mixture Distribution ◽  
Combustion Efficiency ◽  
Spray Angle ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

A free-piston engine is a novel internal combustion engine which has the advantages of a variable compression ratio and multi-fuel adaptability. This paper focuses on numerical simulation for combustion process and spray angle optimization of an opposed-piston free-piston engine. The working principle and spray-guided central combustor structure of the engine are discussed. A three-dimensional computational fluid dynamic model with moving mesh is presented based on the tested piston motion of the prototype. Calculation conditions, spray models, and combustion models were set-up according to the same prototype. The effects of spray angle on fuel evaporation rate, mixture distribution, heat release rate, in-cylinder pressure, in-cylinder temperature, and emissions were simulated and analyzed in detail. The research results indicate that the performance of the engine was very sensitive to the spray angle. The combustion efficiency and the indicated thermal efficiencies of 97.5% and 39.7% were obtained as the spray angle reached 40°.

Study on the combustion process and work capacity of a micro free-piston engine

2015 ◽  
Vol 29 (11) ◽  
pp. 4993-5000 ◽  
Author(s):  
Qian Wang ◽  
Liming Dai ◽  
Kai Wu ◽  
Jin Bai ◽  
Zhixia He
Keyword(s):  
Combustion Process ◽  
Work Capacity ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

Simulation of an Opposed-Piston Four-Stroke Free-Piston Generator

2013 ◽  
Vol 336-338 ◽  
pp. 585-589 ◽  
Author(s):  
Zhao Ping Xu ◽  
Si Qin Chang
Keyword(s):  
Combustion Process ◽  
Electrical Energy ◽  
State Equation ◽  
Ideal Gas ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
Free Piston Engine ◽  
Dynamical Properties ◽  
The Ideal

In order to achieve efficient conversion of the chemical energy of fuel into the electrical energy, a novel opposed-piston four-stroke free-piston generator is developed in this paper by equipping one free-piston engine with two linear generators. Mathematical models of the opposed-piston four-stroke free-piston generator are created based on the kinetic equation of the free-piston motion, the state equation of the ideal gas, and an equivalent heat release function of the combustion process. Dynamical properties of the system are simulated and analyzed by using the created model, and results from the simulation are presented. According to the simulation, the new four-stroke free-piston generator can realize running without vibrations.

Influence of Piston Initial State on HCCI Combustion in Micro Free-Piston Engine Using Experiment Images and CFD Analysis

2013 ◽  
Vol 724-725 ◽  
pp. 1350-1354
Author(s):  
Jin Bai ◽  
Qian Wang ◽  
Zhi Xia He ◽  
Peng Gang Zhang
Keyword(s):  
High Speed ◽  
Ignition Time ◽  
Combustion Process ◽  
Single Shot ◽  
Piston Engine ◽  
Initial State ◽  
Propane Combustion ◽  
Free Piston ◽  
Hcci Combustion ◽  
Free Piston Engine

The visualization experimental setup of micro free-piston engine has been built, the process of single shot compression combustion in micro combustion chamber has been observed by the high-speed digital camera; Based on the propane combustion kinetics, the numerical calculation method for combustion process coupling with the free-piston movement was put forward, through editing the dynamic mesh subroutine in STAR-CD, the process of homogeneous charge compression ignition (HCCI) in the micro chamber was studied; The influence of piston initial state on HCCI combustion process was analyzed , indicating that the piston mass directly affects the homogeneous gas compression ratio, ignition time, single combustion process cycle and the changes of combustion pressure and temperature, all this research can be the basic theories for designing the micro free piston engine .

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