Design and simulation of a two- or four-stroke free-piston engine generator for range extender applications

作者：Jia, Boru; Smallbone, Andrew^*; Zuo, Zhengxing; Feng, Huihua; Roskilly, Anthony Paul

来源：Energy Conversion and Management, 2016, 111: 289-298.

DOI：10.1016/j.enconman.2015.12.063

• Free-piston engine
• Linear electric machine
• Two-stroke cycle
• Four-stroke cycle
• Operating characteristics

Free-piston engines (FPEs) are known to have a greater thermal efficiency (40-50%) than an equivalent and more conventional four-stroke reciprocating engines (30-40%). Modern FPEs are proposed for the generation of electric and hydraulic power, with a potential application in hybrid electric vehicles. The numerous FPE configurations considered to date have almost exclusively operated using a two-stroke thermodynamic cycle to improve the thermal efficiency, however it is well known that the application of two-stoke cycles can be limited by noise and exhaust gas emissions constraints. In this article, a numerical model is used to investigate the techno-feasibility of operating Newcastle University's FPE prototype using a two- or four-stroke thermodynamic cycle. If operated as a four-stroke cycle, the linear generator must be used as both a motor and a generator resulting in a more irregular piston motion compared to corresponding operating in a two-stroke cycle. In four-stroke cycles, almost half the indicated power is consumed in overcoming the pumping losses of the motoring process. Whilst the heat release process is appears to be closer to a constant volume process when operated on two-stroke engine cycle, the peak cylinder pressure and compression ratio proved lower. In addition, a narrower power range is reported for a four-stroke cycle despite a corresponding higher thermal efficiency.

• 出版日期2016-3-1
• 单位北京理工大学