Research on the Operating Characteristics of Hydraulic Free-Piston Engines: A Systematic Review and Meta-Analysis

Fukang Ma, Shuanlu Zhang, Zhenfeng Zhao and Yifang Wang
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Fukang Ma: School of Energy and Power Engineering, North University of China, University Road No.3, Taiyuan 030051, China
Shuanlu Zhang: Beiqi Foton Motor Co., Ltd., Changping Shahe Road, Beijing 102206, China
Zhenfeng Zhao: School of Mechanical and Vehicle Engineering, Beijing Institute of Technology, Zhongguancun South Street No.5, Beijing 100081, China
Yifang Wang: School of Energy and Power Engineering, North University of China, University Road No.3, Taiyuan 030051, China

Energies, 2021, vol. 14, issue 12, 1-23

Abstract: The hydraulic free-piston engine (HFPE) is a kind of hybrid-powered machine which combines the reciprocating piston-type internal combustion engine and the plunger pump as a whole. In recent years, the HFPE has been investigated by a number of research groups worldwide due to its potential advantages of high efficiency, energy savings, reduced emissions and multi-fuel operation. Therefore, our study aimed to assess the operating characteristics, core questions and research progress of HFPEs via a systematic review and meta-analysis. We included operational control, starting characteristics, misfire characteristics, in-cylinder working processes and operating stability. We conducted the literature search using electronic databases. The research on HFPEs has mainly concentrated on four kinds of free-piston engine, according to piston arrangement form: single piston, dual pistons, opposed pistons and four-cylinder complex configuration. HFPE research in China is mainly conducted in Zhejiang University, Tianjin University, Jilin University and the Beijing Institute of Technology. In addition, in China, research has mainly focused on the in-cylinder combustion process while a piston is free by considering in-cylinder combustion machinery and piston dynamics. Regarding future research, it is very important that we solve the instabilities brought about by chance fluctuations in the combustion process, which will involve the hydraulic system’s efficiency, the cyclical variation, the method of predicting instability and the recovery after instability.

Keywords: hydraulic free-piston engine; operating characteristics; research progress; systematic review; meta-analysis (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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