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.

Thermodynamic Simulation and Prototype Testing of a Four-Stroke Free-Piston Engine

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Jiming Lin ◽  
Zhaoping Xu ◽  
Siqin Chang ◽  
Ningxia Yin ◽  
Hao Yan
Keyword(s):  
Thermodynamic Simulation ◽  
Thermodynamic Cycle ◽  
Energy Conversion Efficiency ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Simulation And Experiment ◽  
Intake Stroke ◽  
Engine System ◽  
Insight Into

In order to achieve higher-energy conversion efficiency, a free-piston engine with an improved four-stroke thermodynamic cycle is investigated in this paper. This cycle is optimized according to the variable strokes feature and is characterized by the short intake stroke, the complete expansion stroke, the external pressurization, and the intercooling. The development of a four-stroke free-piston engine system simulation model was described, and the effects of the cycle on the system performances were qualitatively analyzed. According to the experiment of the prototype, the generating efficiency of 33.4% can be achieved when the system is fueled with gasoline and the output power is significantly increased from 1.62 to 2.68 kW. The simulation and experiment results are analyzed in detail, giving insight into the performances of the system. Studies show that the energy-saving and environmental protection performances of the system can be significantly promoted by using the improved thermodynamic cycle.

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.

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.

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%.

scholarly journals Stable Operation and Electricity Generating Characteristics of a Single-Cylinder Free Piston Engine Linear Generator: Simulation and Experiments

Energies ◽  
2015 ◽  
Vol 8 (2) ◽  
pp. 765-785 ◽  
Author(s):  
Huihua Feng ◽  
Yu Song ◽  
Zhengxing Zuo ◽  
Jiao Shang ◽  
Yaodong Wang ◽  
...  
Keyword(s):  
Stable Operation ◽  
Piston Engine ◽  
Free Piston ◽  
Single Cylinder ◽  
Linear Generator ◽  
Free Piston Engine

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.

A Starting Control Strategy of Single-Cylinder Two-Stroke Free-Piston Engine Generator

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Jinkang Lu ◽  
Zhaoping Xu ◽  
Dong Liu ◽  
Liang Liu
Keyword(s):  
Control Strategy ◽  
Cold Start ◽  
Combustion Model ◽  
Piston Engine ◽  
Free Piston ◽  
Single Cylinder ◽  
Free Piston Engine ◽  
Start Up ◽  
Turning Center ◽  
Starting Process

Abstract Free-piston engine generator is a novel energy conversion system, which is known to have advantages of variable compression ratio and variable fuel. The free-piston must be controlled to overcome challenges like misfire, after-combustion, and other abnormal combustion in the starting process, as well as to prevent the piston from colliding with the cylinder head. This article proposes a control strategy based on the combustion state for the cold start-up process of single-cylinder two-stroke free-piston engine generator. The combustion state is judged based on in-cylinder pressure at the early beginning of expansion stroke, and the duration and direction of coil current are adjusted to ensure the aimed bottom turning center of the stroke. A control-oriented model including the cold start-up combustion model of the prototype is presented, and the control strategy is verified by the experiment of the prototype. The results show that the free-piston engine generator can start successfully and overcome abnormal combustion during the cold start-up process.

scholarly journals Simulation model “free-piston engine – electromechatronic converter on the basis of an electrical generator reciprocating”

2020 ◽  
Vol 65 (1) ◽  
pp. 83-96
Author(s):  
A. B. Menzhinsky ◽  
A. N. Malashin
Keyword(s):  
Simulation Model ◽  
Mechanical Energy ◽  
Reciprocating Motion ◽  
Piston Engine ◽  
Free Piston ◽  
Operating Cycle ◽  
Power Sources ◽  
Electric Generator ◽  
Model Free ◽  
Free Piston Engine

The analysis of the state and prospects of development of autonomous electric power sources with electric reciprocating motion generators has shown that at present, low-power systems “free-piston engine – electromechanotron сonverter based on an electric reciprocating motion generator” are widely used. Studies of electric reciprocating generators have shown that special attention should be paid to combined generators that can improve the efficiency of such a system. However, until now, the study of the system “free-piston engine – electromechanotron сonverter based on a combined electric reciprocating generator” has not been given due attention. In this regard, a simulation model of the system “free-piston engine – electromechanotron сonverter based on an electric generator of reciprocating motion” was developed, which allows conducting research of this system in various operating modes when changing the parameters of the electrical and mechanical subsystems. A distinctive feature of the developed simulation model is the consideration of the features of simultaneous use in the magnetic system of an electric generator of reciprocating motion of transverse and longitudinal nonlinear changes in magnetic flows. As a result of the simulation model studies, it is shown that the combined electric generator of reciprocating motion allows for continuous conversion of mechanical energy of reciprocating motion into electricity over the entire operating cycle, as well as – to compensate for the mismatch of the forces of the electrical and mechanical subsystems of the system “free-piston engine – electromechanotron converter based on an electric generator of reciprocating motion”.

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