Advanced combustion free-piston engines: A comprehensive review

Zhou, Yingcong; Sofianopoulos, Aimilios; Lawler, Benjamin; Mamalis, Sotirios

doi:10.1177/1468087418800612

Cited by 24 publications

(7 citation statements)

References 104 publications

(260 reference statements)

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“…These incidences are shown in the graph in Figure 4. The reason for this phenomenon is the existence of crevice volume in the bounce chamber, a common structural feature of an engine cylinder, from the original simulation model for a dual-sided FPLG [22]. In the present research, a crevice volume is no longer required as there is no combustion taking place in the BC.…”

Section: No-load Operation: Variation Of Structural Parameter and Com...mentioning

confidence: 90%

Impact of Combustion Variance on Sustainability of Free-Piston Linear Generator during Steady-State Generation

et al. 2021

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A free-piston linear generator (FPLG) has a number of advantages compared to a traditional crank-slider internal combustion engine, including better thermal and mechanical efficiencies, different fuel compatibility, and a higher power-to-weight ratio. For electric vehicle propulsion and generation of portable power, an FPLG is a very attractive alternative source of energy. This paper presents the development of an FPLG simulation model using MATLAB-Simulink and investigates the impact of combustion variance on its operation. Results provided insight into various characteristics of system behavior through variation of structural dimension and operational parameters. In steady-state operation with fixed electrical load and fixed ignition for combustion, it was found that consecutively low combustion pressures can easily lead to engine stoppage, pointing to the significance of control for continuous operation. Due to the absence of the moment of inertia and flywheel character of the rotating engine, a linear engine-generator is subject to ceased operation even after two consecutively low combustions under 10% variance. This will not be a fundamental problem in an ordinary crank-slider engine-generator, but in a linear engine-generator, control measure will be necessary to ensure sustained operation.

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Section: No-load Operation: Variation Of Structural Parameter and Com...mentioning

confidence: 90%

Impact of Combustion Variance on Sustainability of Free-Piston Linear Generator during Steady-State Generation

et al. 2021

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“…The effective control of FP-LEGs requires an integrated analysis of the system’s mechanical and electrical sides. Most of the review works on FP-LEG focused on either the engine development and control, 10 combustion, 23 or generator control. 24 A systematic evaluation addressing the research and developmental challenges and efforts of linear engines and linear generators is essential to clarify specific technical challenges and current progress and suggest the future research direction required.…”

Section: Introductionmentioning

confidence: 99%

Recent progress on performance and control of linear engine generator

Ngwaka

Chen

Qiu

et al. 2022

International Journal of Engine Research

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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.

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“…1,2 It has the features of compact structure, short transfer path, variable compression ratio, free movement, and flexible combustion drive. 3,4 At the same time, unlike the traditional piston engines, FPHS has no crank-connecting rod mechanism and is coupled by combustion drive, power transmission, piston motion, electromagnetic load generation, lubrication friction, and gas exchange during operation. Its motion law is very complex, which greatly affects its operation stability.…”

Section: Introductionmentioning

confidence: 99%

The effect of electromagnetic load fluctuation on the gas exchange stability of a free-piston hybrid power system

Yuan

2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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The free-piston hybrid power system (FPHS) is affected by the dynamic coupling of combustion drive, power transmission, piston motion, excitation generation and gas exchange, and its operating state is very different from that of traditional engines. In this paper, the influence of the change of electromagnetic load on the ventilation stability of the whole system is studied by combining the method of system simulation and experimental validation. A dynamic-ventilation one-dimensional coupled gas exchange model was established, and the influence of the fluctuation of the electromagnetic load on the gas exchange is simulated by combining the thermodynamic model with the magnetic inductive load model. The results show that the scavenging efficiency is positively correlated with the load fluctuation, while the trapping efficiency changes with the opposite rule. Specifically, increasing the electromagnetic load properly will increase the time of gas exchange and obtain more fresh charge. The reduction of the electromagnetic load will make the compression process have higher gas pressure and temperature, which the mixture of oil and gas is more homogeneous and the combustion rate is faster after ignition. The stability of the ventilation performance of FPHS is very sensitive to electromagnetic fluctuations. The control of FPHS system can be achieved by adjusting the electromagnetic load.

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Advanced combustion free-piston engines: A comprehensive review

Cited by 24 publications

References 104 publications

Impact of Combustion Variance on Sustainability of Free-Piston Linear Generator during Steady-State Generation

Impact of Combustion Variance on Sustainability of Free-Piston Linear Generator during Steady-State Generation

Recent progress on performance and control of linear engine generator

The effect of electromagnetic load fluctuation on the gas exchange stability of a free-piston hybrid power system

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