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Investigation of the Starting Process of Free-piston Engine Generator by Mechanical Resonance

Lookup NU author(s): Dr Boru Jia, Dr Guohong Tian, Professor Tony Roskilly



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


As an alternative to conventional engines, free-piston engine generator (FPEG) is a promising power generation system due to its simplicity and high thermal efficiency. One crucial technical challenge in the FPEG operation is the initial process of overcoming the compression force to achieve a certain speed which allows a stable and continuous operation, i.e. starting process. This paper proposes a novel method to start the engine by mechanical resonance. A closed-loop control model was developed and implemented in a prototype FPEG which was driven by a linear machine with a constant driving force. Both numerical and experimental investigation was carried out. The results show that once the linear motor force have overcome the initial friction force, both the in-cylinder peak pressure and the amplitude of the piston motion would increase gradually by resonance and quickly achieve the target for ignition. With a fixed motor force of 110N, within 0.8 second, the maximum in-cylinder pressure can achieve 12 bars, the compression ratio can reach 9:1, and the engine is ready for ignition. The results demonstrated that it is feasible to start the FPEG by mechanical resonance in a constant motor force in the direction of the natural bouncing motion.

Publication metadata

Author(s): Jia B, Zuo Z, Feng H, Tian G, Roskilly AP

Publication type: Article

Publication status: Published

Journal: Energy Procedia

Year: 2014

Volume: 61

Pages: 572-577

Online publication date: 12/01/2015

Acceptance date: 30/05/2014

Date deposited: 27/06/2017

ISSN (electronic): 1876-6102

Publisher: Elsevier BV




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