Experimental study on the operating characteristics of a reciprocating free-piston linear engine

Huang, Fujun; Kong, Wenjun

doi:10.1016/j.applthermaleng.2019.114131

Cited by 14 publications

(7 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Chinese Academy of Sciences investigated a two-stroke methane-fuelled mini FP-LEG for improved performance. 52 The test setup explored glow plug ignition (GPI) and SI starting modes. The glow plug performs a similar role as the spark plug in the conventional SI engine, and the ignition timing is controlled electronically for the spark plug.…”

Section: Linear Engine Developmentsmentioning

confidence: 99%

Recent progress on performance and control of linear engine generator

Ngwaka

Chen

Qiu

et al. 2022

International Journal of Engine Research

View full text Add to dashboard Cite

Linear engines, or widely called free piston engines, have their advantages compared to conventional engines with crankshafts, for example, lower friction loss, compact structure, fuel adaptability, flexible compression ratio, etc. Among the linear engine conceptual designs and prototypes, Linear Engine Generator (LEG) incorporating a linear engine (internal or external combustion) and a linear alternator provides an alternative and attractive solution for hybrid electrical powertrains in transport applications. Due to the advantages of linear engines, hydrogen, synthetic hydrogen carrier fuels and biofuels are easier to adopt on LEG, making it an appealing technology for decarbonisation. This paper explicitly reviews LEG research and development on state-of-art solutions and recent progress in linear engine improvement, linear alternator design optimisation, and integrated LEG system control. Key performance indicators of the linear engine generator, like power output, thermal and electrical efficiency, etc., are summarised to present a general picture of up-to-date LEG development. Recommendations for further LEG development are provided at the end of the paper regarding the review outcomes.

show abstract

Section: Linear Engine Developmentsmentioning

confidence: 99%

Recent progress on performance and control of linear engine generator

Ngwaka

Chen

Qiu

et al. 2022

International Journal of Engine Research

View full text Add to dashboard Cite

show abstract

“…Compared with conventional hybrid power, 10,11 its piston movement is not restricted by any mechanical mechanism, 12 which has the characteristics of simple structure, variable trajectory and dead point, and flexible combustion control. [13][14][15][16] It has become research hotspots of onboard extended range power. As a promising energy conversion device, LEG has potential benefits over traditional internal combustion engines (TCE) in terms of efficiency and emissions, which has been extensively studied.…”

Section: Introductionmentioning

confidence: 99%

Gas exchange stability of linear engine generator under fuel injection quantity fluctuation

Lifu

Yuan

Zeng

2022

Proceedings of the Institution of Mechanical Engineers, Part D:

View full text Add to dashboard Cite

Gas exchange instability is an important issue that affects the stability of the linear engine generator (LEG). Fuel injection quantity fluctuation is a potential disturbance factor that induces LEG gas exchange instability. In order to grasp the impact of fuel injection quantity changes on LEG under the action of multi-field coupling the effect of gas exchange stability, a numerical model of the coupling of motion-combustion-gas exchange multiprocessing is constructed, and the calculation method of cyclic iteration of the simulation results of each process is adopted to simulate and study the performance characteristics of the LEG gas exchange process under the fluctuation of fuel injection. The results demonstrate that the reciprocating frequency, movement stroke of LEG, and the fluctuation of fuel injection quantity present positive correlation characteristics. The increase of fuel injection quantity causes the piston to move faster near the reciprocating dead point, so the time provided for the gas exchange flow is compressed. Moreover, the increase in fuel injection quantity means that more fuel participates in the combustion process, releases more heat, and enhances the pressure and temperature of the gas in the cylinder. Although this is conducive to the rapid discharge of more combustion exhaust gas in the free exhaust phase, due to the shortening of the gas exchange flow time. The actual exhaust gas scavenging efficiency decreases with the increase of the fuel injection quantity and the corresponding fresh charge trapping efficiency shows an increasing trend.

show abstract

“…A micro linear power generation system was proven to reach an energy density of 180 Whr/kg [8], which is on the upper limit of rechargeable lithium batteries [9]. A variety of small-scale heat engine prototypes have been developed and investigated in the form of micro gas turbines [7,[10][11][12][13], micro rotor engines [14][15][16], micro internal combustion swing engines [17][18][19], micro free-piston generators [20][21][22][23], micro steam turbine [24][25][26] and micro P 3 (Personal Power Pack) external combustion engines [27,28].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, Tian et al [37] contributed the low conversion efficiency of around 0.6% of their free-piston compressor to the combined effect of severe leakage, heat transfer and friction. Huang et al [21] tested the performance of a reciprocating free-piston linear engine with a pair of 22.4 mm diameter combustion chambers. The engine output was 31.6 W power and it attained 42.8% thermal efficiency with an external resistance of 6.3 Ω.…”

Section: Introductionmentioning

confidence: 99%

Parametric Simulations on Leakage and Performance of a Miniature Free-Piston Generator (MFPG)

Zhang

Liu

et al. 2021

Applied Sciences

View full text Add to dashboard Cite

The miniaturization of electrical equipment and popularization of portable devices is an appealing motivation for the development of small-scale heat engines. However, the in-cylinder charge leaks severely as the engine dimension shrinks. The free-piston engine on a small scale provides better sealing than other miniature heat engines. Therefore, a miniature free-piston generator (MFPG) with a single-piston internal combustion engine (ICE) and a voice coil motor (VCM) was proposed in this work. A dynamic model with special attention on the heat transfer and leakage was established accordingly, upon which parametric studies of leakage and its effects on the performance of the MFPG system were performed. Four key parameters, including scavenging pressure, ignition position, combustion duration and piston mass, were considered in the model. The results showed that the mass leakage during the compression decreases with the rise of the motoring current. The indicated thermal efficiency can be improved by boosting scavenging pressure and increase motoring current. The critical ignition position is 2 mm before the top dead center. When ignition occurs later than that, the MFPG system is incapable of outputting power. The chemical to electric energy conversion efficiency is about 5.13 %, with an output power of 10~13 W and power density around 4.7~5.7 W/cc.

show abstract

Experimental study on the operating characteristics of a reciprocating free-piston linear engine

Cited by 14 publications

References 30 publications

Recent progress on performance and control of linear engine generator

Recent progress on performance and control of linear engine generator

Gas exchange stability of linear engine generator under fuel injection quantity fluctuation

Parametric Simulations on Leakage and Performance of a Miniature Free-Piston Generator (MFPG)

Contact Info

Product

Resources

About