Study on the Motion Characteristics of a Hydraulic Free-Piston Engine

2014 ◽  
Vol 889-890 ◽  
pp. 390-393
Author(s):  
Shi Yu Li ◽  
Zhao Cheng Yuan ◽  
Jia Yi Ma
Keyword(s):  
Fuel Injection ◽  
Fuel Efficiency ◽  
Injection Timing ◽  
Piston Engine ◽  
Free Piston ◽  
Fuel Injection Timing ◽  
Free Piston Engine ◽  
Center Position ◽  
Working Frequency ◽  
Motion Characteristics

Hydraulic free-piston engines have potential advantages of cost and fuel efficiency. Due to no crankshaft system, it is difficult and important to control the piston motion and working frequency precisely. This paper studies on the motion characteristics for the hydraulic free-piston engine effects of operation parameters, and results are presented. The TDC (Top Dead Center) position and CR (Compression Ration) are great influenced by starting pressure and fuel injection timing, and working frequency is mainly influenced by piston mass, starting pressure and fuel quantity.

Motion Characteristics and Influence Factors of Piston Assembly in a Compression-Ignition Hydraulic Free-Piston Engine

2013 ◽  
Vol 860-863 ◽  
pp. 1761-1765
Author(s):  
Ying Xiao Yu ◽  
Zhao Cheng Yuan ◽  
Jia Yi Ma ◽  
Shi Yu Li
Keyword(s):  
Fuel Injection ◽  
Influence Factors ◽  
Basic Structure ◽  
Injection Timing ◽  
Compression Ignition ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Motion Characteristics ◽  
Piston Assembly

The advantages and basic structure of hydraulic free-piston engine (HFPE) were presented. And the operation principle of a single piston compression-ignition HFPE was analyzed. Based on the basic theory of thermodynamics, hydraulic fluid mechanics and dynamics, the system simulation model for a single-piston compression-ignition HFPE was established in the environment of MATLAB/SIMULINK. The simulation results, which accord with the related literature data, indicate that the asymmetric characteristics of piston motion in the entire cycle are very obvious, the compression stroke duration is longer than the expansion stroke, the time at around the top dead center (TDC) is short. The piston assembly motion is a process when the energy balance is fulfilled, and some factors must be taken into account for design optimization, such as the piston assembly mass, compression accumulator pressure, fuel injection timing and fuel injection quantity.

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.

Energy and exergy analysis of hydraulic free-piston engines

2018 ◽  
Vol 233 (12) ◽  
pp. 3074-3087 ◽  
Author(s):  
Lei Wang ◽  
Zhenfeng Zhao ◽  
Chuncun Yu ◽  
Fujun Zhang ◽  
Changlu Zhao
Keyword(s):  
Thermal Efficiency ◽  
Waste Heat ◽  
Energy Utilization ◽  
Injection Timing ◽  
Characteristic Parameters ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

A hydraulic free-piston engine is an unconventional reciprocating piston internal combustion engine in which the piston assembly motion is determined by in-cylinder gas pressure and load force. Fuel combustion energy is directly converted into hydraulic energy. These affect the work process of cylinder and efficiency of energy conversion. In order to study the energy utilization efficiency and to explore the recovery potential of waste heat energy of hydraulic free-piston engine, in this paper, the energy distribution and waste heat energy characteristics of hydraulic free-piston engine have been studied by combining energy and exergy analysis. The thermal efficiency was analyzed by the first law of thermodynamics, and exergy balance was analyzed by the second law. The effect of the characteristic parameters on the thermal and exergy efficiency was studied through the simulation analysis comparing the energy utilization of hydraulic free-piston engine and conventional engines. The results show that control of the injection timing parameter is effective for optimizing efficiency because the cycle characteristic parameters can be controlled by changing the injection timing. The experimental results show that the thermal efficiency is 40.8% and the exergy efficiency is 46.3%. The simulation result show that the thermal efficiency of hydraulic free-piston engine is 38.0% and the conventional diesel engine is 33.0%.

Research on Hydraulic Free Piston Engine with High Scavenging Efficiency

2015 ◽  
Vol 779 ◽  
pp. 187-191
Author(s):  
Hao Ling Ren ◽  
Tian Liang Lin ◽  
Hai Bo Xie
Keyword(s):  
Diesel Engine ◽  
Fuel Injection ◽  
Injection System ◽  
Fuel Injection System ◽  
Piston Engine ◽  
Free Piston ◽  
The Poor ◽  
Free Piston Engine ◽  
Scavenging Efficiency ◽  
Stroke Engine

The poor scavenging process of the hydraulic free piston engine which uses two-stroke engine as its driver was presented. A two-cylinder, four-stroke diesel engine was proposed to drive the single-piston hydraulic free piston engine to improve the scavenging process. The intake and release valves mechanism and fuel injection system were redesigned to adapt the performance of the single-piston hydraulic free piston engine. Feasibility and reliability of this new structure are verified through simulation.

scholarly journals Effects of five different parameters on biodiesel HCCI combustion in free-piston engine generator

2021 ◽  
Vol 25 (6 Part A) ◽  
pp. 4197-4207
Author(s):  
Chunhui Liu ◽  
Shaojie Wu ◽  
Shuo Pang
Keyword(s):  
Initial Pressure ◽  
Piston Engine ◽  
Detailed Chemical Kinetics ◽  
Free Piston ◽  
Hcci Combustion ◽  
Free Piston Engine ◽  
Combustion Simulation ◽  
Working Frequency ◽  
Skeletal Mechanism ◽  
Detailed Chemical

A coupled 3-D CFD and detailed chemical kinetics model of free-piston engine generator (FPEG) was adopted to investigate the effects of initial parameters on homogeneous charge compression ignition (HCCI) combustion and emission. Biodiesel with 115 species skeletal mechanism was selected as fuel. Five different parameters, namely the initial pressure, the initial temperature, the working frequency, the compression ratio and the fuel equivalence ratio, were selected to analyze their influences in the HCCI combustion simulation of FPEG. The simulation results showed that the change of the five parameters had visible impact on the heat release rate of HCCI combustion, which caused the in-cylinder temperature and pressure to change, and also caused the emission content of NOx and SOOT to change obviously.

Simulation Research on the Basic Performance of a Single Piston Hydraulic Free-Piston Engine

2014 ◽  
Vol 889-890 ◽  
pp. 385-389
Author(s):  
Shi Yu Li ◽  
Zhao Cheng Yuan ◽  
Jia Yi Ma ◽  
Qing Zhu
Keyword(s):  
Simulation Model ◽  
Hydraulic Pump ◽  
Piston Engine ◽  
Free Piston ◽  
Simulation Research ◽  
Free Piston Engine ◽  
Basic Performance ◽  
Conventional Technology ◽  
Motion Characteristics

Hydraulic free-piston engine is a compact machine which is composed of a conventional engine and a hydraulic pump. Compared to the conventional technology, the free piston engine has many potential advantages. In this paper, a simulation model for a single piston hydraulic free-piston engine (SPHFPE) is described, and the differences in motion characteristics between the free-piston engine and the conventional engine are presented. And varying piston mass and starting pressures have an impact on the motion characteristics of the free-piston engine.

Operation of a turbine-compound free-piston linear alternator

2021 ◽  
pp. 146808742110159
Author(s):  
Chang-Ping Lee ◽  
Claus Borgnakke ◽  
Russell Durrett
Keyword(s):  
Injection Timing ◽  
Actual Behavior ◽  
Piston Engine ◽  
Combustion Chambers ◽  
Free Piston ◽  
Free Piston Engine ◽  
Linear Alternator ◽  
Mechanical Models ◽  
Control Volumes ◽  
Engine Map

A free-piston linear-alternator combined with combustion chambers has been examined in many studies. However, only simplified thermodynamic and mechanical models were developed to mimic the actual behavior of the free-piston engine. The purpose of this study is to establish a fully dynamic model that can calculate the energy transformation under the operation of the free-piston engine. The Matlab/Simulink® model uses non-constant-volume combustion event, the piston transient dynamics, flow, heat losses, and thermodynamics as bridges to connect control volumes. The model successfully captured the behavior and measurements of a GS-34 free-piston engine, based on a thermodynamic calculation calibrated with experimental data. The resulting model is used for a series of parametric studies to understand the very complex system behavior, including low load operation. Operation parameters (injection timing and bounce chamber mass) are optimized to generate the engine map for different alternator sizes. At the end, the advantages of the opposed free-piston engine with a linear alternator are presented through the energy analysis.

Investigation of late fuel injection position on the combustion of free piston engine

2018 ◽  
Author(s):  
Salah E. Mohammed ◽  
N. A. Ramlan ◽  
A. Rashid A. Aziz ◽  
F. Firmansyah ◽  
Z. Ezrann Zainal
Keyword(s):  
Fuel Injection ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

scholarly journals Two-Stroke Thermodynamic Cycle Optimization of a Single-Cylinder Free-Piston Engine Generator

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Houliang Yu ◽  
Zhaoping Xu ◽  
Qinglin Zhang ◽  
Liang Liu ◽  
Ru Hua
Keyword(s):  
Simulation Model ◽  
Performance Optimization ◽  
Thermodynamic Cycle ◽  
Prototype System ◽  
Injection Timing ◽  
Connecting Rod ◽  
Piston Engine ◽  
Free Piston ◽  
Single Cylinder ◽  
Free Piston Engine

A free-piston engine generator (FPEG) is a new type of energy converter, which eliminates the crankshaft and connecting rod mechanism. In order to achieve efficient energy conversion, the two-stroke thermodynamic performance optimization of a single-cylinder free-piston engine generator is investigated in this paper. Firstly, the components, four-stroke thermodynamic cycle, two-stroke thermodynamic cycle, and prototype system of the FPEG are presented in detail. The one-dimensional flow simulation model of the FPEG is created based on the gas dynamics equation, Weber combustion function, and heat transfer function, and then the model is validated by the data tested from the prototype system. According to the four-stroke experimental results of the FPEG, an effective power of 4.75 kW and a peak pressure of 21.02 bar have been obtained. Then, the two-stroke thermodynamic cycle is simulated and compared under the different control parameters of intake air pressure, injection timing, ignition timing, and valve timing through the simulation model. The optimized results show that an indicated thermal efficiency of 27.6%, an indicated power of 6.7 kW, and a maximal working frequency of 25 Hz can be achieved by the prototype system, when the two-stroke thermodynamic cycle is used.

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