A study of a two-stroke free piston linear engine using numerical analysis

Hung, Nguyen Ba

doi:10.1007/s12206-014-0141-3

Cited by 41 publications

(25 citation statements)

References 10 publications

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“…i 21 and i 22 are also the regulated currents in the compression stroke; there correspond with the displacement from BDC to TDC. Their reference currents can be calculated by the Equations (22), (27)- (29). When the fuel mass changes from 30 to 35 mg, the value of i 11 (−35.7 A) increases to i 11 (−53.6 A).…”

Section: The Stability Of Ladder-like Control Schemementioning

confidence: 99%

“…Due to that increasing fuel mass is an effective way to increase the output power [7,23,28,29], the relationship between the output power and the electromagnetic force profile is seldom noticed. In the previous research most researchers only pay attention to the stable operator of the piston.…”

Section: Introductionmentioning

confidence: 99%

“…There are many generic function models used to represent the heat transfer between the in-cylinder working medium and wall. Here, the Hohenberg model is used to describe this process [29]:…”

mentioning

confidence: 99%

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A Free-Piston Linear Generator Control Strategy for Improving Output Power

Zhang

Chen

et al. 2018

Energies

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This paper presents a control strategy to improve the output power for a single-cylinder two-stroke free-piston linear generator (FPLG). The comprehensive simulation model of this FPLG is established and the operation principle is introduced. The factors that affect the output power are analyzed theoretically. The characteristics of the piston motion are studied. Considering the different features of the piston motion respectively in acceleration and deceleration phases, a ladder-like electromagnetic force control strategy is proposed. According to the status of the linear electric machine, the reference profile of the electromagnetic force is divided into four ladder-like stages during one motion cycle. The piston motions, especially the dead center errors, are controlled by regulating the profile of the electromagnetic force. The feasibility and advantage of the proposed control strategy are verified through comparison analyses with two conventional control strategies via MatLab/Simulink. The results state that the proposed control strategy can improve the output power by around 7-10% with the same fuel cycle mass.

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Section: The Stability Of Ladder-like Control Schemementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Free-Piston Linear Generator Control Strategy for Improving Output Power

Zhang

Chen

et al. 2018

Energies

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“…The entire system can be seen as an open system. Assuming that at any instant in time the temperature and pressure in the cylinder are in thermodynamic equilibrium, and ignoring the effects of vaporizing liquid droplets, fluid flow, combustion chamber geometry or spatial variations of the mixture's composition, the equations describing the state in the cylinder are the conservation of mass and the first law of thermodynamics [2,4,5,24]:…”

Section: Thermodynamic Modellingmentioning

confidence: 99%

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

et al. 2015

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Abstract:We present a novel design of a single-cylinder free piston engine linear generator (FPELG) incorporating a linear motor as a rebound device. A systematic simulation model of this FPELG system was built containing a kinematic and dynamic model of the piston and mover, a magneto-electric model of the linear generator, a thermodynamic model of the single-cylinder engine, and a friction model between the piston ring and cylinder liner. Simulations were performed to understand the relationships between pre-set motor parameters and the running performance of the FPELG. From the simulation results, it was found that a motor rebound force with a parabolic profile had clear advantages over a force with a triangular profile, such as a higher running frequency and peak cylinder pressure, faster piston motion, etc. The rebound position and the amplitude of rebound force were also determined by simulations. The energy conversion characteristics of the generator were obtained from our FPELG test rig. The parameters of intake pressure, motor frequency, and load resistance were varied over certain ranges, and relationships among these three parameters were obtained. The electricity-generating characteristic parameters include output power and system efficiency, which can measure OPEN ACCESSEnergies 2015, 8 766 the quality of matching the controllable parameters. The output power can reach 25.9 W and the system efficiency can reach 13.7%. The results in terms of matching parameters and electricity-generating characteristics should be useful to future research in adapting these engines to various operating modes.

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“…However, limited by the factors summarised in [2], the research on these types of free piston engines stagnated after the 1960s. In recent decades, dramatic developments in the technologies of electrical motors and electronic control have made it possible to address the research difficulties of free piston engines, and most importantly, extended the research concerns to applications of a free piston engine coupled with a linear motor or a hydraulic sub-system [9][10][11][12][13][14][15][16][17][18]. The compression ignition (CI) free piston engine coupled with a linear motor (FPLG) is the very type of free piston engine studied in this paper, and a detailed illustration of structure and the operating principle of this type of free piston engine can be found in [2].…”

Section: Introductionmentioning

confidence: 99%

Study of the Injection Control Strategies of a Compression Ignition Free Piston Engine Linear Generator in a One-Stroke Starting Process

et al. 2016

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For a compression ignition (CI) free piston engine linear generator (FPLG), injection timing is one of the most important parameters that affect its performance, especially for the one-stroke starting operation mode. In this paper, two injection control strategies are proposed using piston position and velocity signals. It was found experimentally that the injection timing's influence on the compression ratio, the peak in-cylinder gas pressure and the indicated work (IW) is different from that of traditional reciprocating CI engines. The maximum IW of the ignition starting cylinder, say left cylinder (LC) and the right cylinder (RC) are 132.7 J and 138.1 J, respectively. The thermal-dynamic model for simulating the working processes of the FPLG are built and verified by experimental results. The numerical simulation results show that the running instability and imbalance between LC and RC are the obvious characters when adopting the injection strategy of the velocity feedback. These could be solved by setting different triggering velocity thresholds for the two cylinders. The IW output from the FPLG under this strategy is higher than that of adopting the position feedback strategy, and the maximum IW of the RC could reach 162.3 J. Under this strategy, the prototype is able to achieve better starting conditions and could operate continuously for dozens of cycles.

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A study of a two-stroke free piston linear engine using numerical analysis

Cited by 41 publications

References 10 publications

A Free-Piston Linear Generator Control Strategy for Improving Output Power

A Free-Piston Linear Generator Control Strategy for Improving Output Power

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

Study of the Injection Control Strategies of a Compression Ignition Free Piston Engine Linear Generator in a One-Stroke Starting Process

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