Comparison of the gas exchange of a loop scavenged free-piston engine alternator and the conventional engine

Abstract The free-piston engine alternator (FPEA) is a new energy conversion engine system, which moves without mechanical restriction. This paper aims to compare the gas-exchange performance of a two-stroke, loop scavenged, diesel FPEA and a corresponding conventional reciprocating engine through numerical modeling. A gas exchange model which coupled with piston dynamic and combustion was developed, and an iterative calculation method was used to simulate the model. The different effects of the piston motion and combustion on the gas exchange in the FPEA and the conventional engine were discussed. The results make it clear that the FPEA has shorter gas exchange duration and more residual burned products than the conventional engine because its piston moves faster in the gas exchange process, which causes the scavenging efficiency of FPEA to be more inferior. While the FPEA has more in-cylinder burned gas through the exhaust port flowing to outside in free blow-down stage, less fresh air through the scavenging port flowing into the cylinder in forced scavenging stage, and more in-cylinder fresh through the exhaust port flowing to the outside in additional exhaust stage.

[1]  Gangchul Kim,et al.  An experimental study on the effects of spring stiffness on the combustion and dynamic characteristics of a linear engine , 2014, Journal of Mechanical Science and Technology.

[2]  Zhengxing Zuo,et al.  Parameters coupling designation of diesel free-piston linear alternator , 2011 .

[3]  R. Mikalsen,et al.  The design and simulation of a two-stroke free-piston compression ignition engine for electrical power generation , 2008 .

[4]  M. Harasek,et al.  CFD simulation of straight and slightly swirling turbulent free jets using different RANS-turbulence models , 2015 .

[5]  Mahdi Shahbakhti,et al.  Modeling of combustion phasing of a reactivity-controlled compression ignition engine for control applications , 2016 .

[6]  Shigehiko Kaneko,et al.  Diesel combustion model for on-board application , 2016 .

[7]  Shuai Guan,et al.  Three-dimensional CFD (computational fluid dynamics) analysis of scavenging process in a two-stroke free-piston engine , 2014 .

[8]  Anthony Paul Roskilly,et al.  Research on combustion process of a free piston diesel linear generator , 2016 .

[9]  Jing Xu,et al.  Performance characteristics analysis of a hydrogen fueled free-piston engine generator , 2016 .

[10]  Ocktaeck Lim,et al.  A study of operating parameters on the linear spark ignition engine , 2015 .

[11]  S. Sreedhara,et al.  Modelling of methanol and H2/CO bluff-body flames using RANS based turbulence models with conditional moment closure model , 2016 .

[12]  Hui-hua Feng,et al.  An experimental research on the combustion and heat release characteristics of a free-piston diesel engine generator , 2017 .

[13]  Fujun Zhang,et al.  Thermodynamic and energy saving benefits of hydraulic free-piston engines , 2016 .

[14]  Chenheng Yuan,et al.  Friction characteristics of piston rings in a free-piston engine generator , 2017 .

[15]  Y. J. Lee,et al.  Free piston engine generator: Technology review and an experimental evaluation with hydrogen fuel , 2014 .

[16]  R. Rezaei,et al.  Phenomenological modeling of combustion and NOx emissions using detailed tabulated chemistry methods in diesel engines , 2016 .

[17]  R. Mikalsen,et al.  Coupled dynamic-multidimensional modelling of free-piston engine combustion. ⋆ , 2009 .

[18]  S. M. Sarathy,et al.  Improved combustion kinetic model and HCCI engine simulations of di-isopropyl ketone ignition , 2016 .

[19]  K. A. Subramanian,et al.  CFD analysis on effect of localized in-cylinder temperature on nitric oxide (NO) emission in a compression ignition engine under hydrogen-diesel dual-fuel mode , 2016 .

[20]  Denis Veynante,et al.  Turbulent combustion modeling , 2002, VKI Lecture Series.

[21]  Wen Li,et al.  Multi-dimensional scavenging analysis of a free-piston linear alternator based on numerical simulation , 2011 .

[22]  Jin Xiao,et al.  Simulation of a Two-Stroke Free-Piston Engine for Electrical Power Generation , 2008 .

[23]  George Kosmadakis,et al.  Methane/hydrogen fueling a spark-ignition engine for studying NO, CO and HC emissions with a research CFD code , 2016 .

[24]  C. Rutland,et al.  Simulations of diesel–methanol dual-fuel engine combustion with large eddy simulation and Reynolds-averaged Navier–Stokes model , 2014 .

[25]  Ocktaeck Lim,et al.  A study of a two-stroke free piston linear engine using numerical analysis , 2014 .

[26]  R. Mikalsen,et al.  The control of a free-piston engine generator. Part 1: Fundamental analyses , 2010 .

[27]  R. Mikalsen,et al.  Performance simulation of a spark ignited free-piston engine generator , 2008 .

[28]  Sungwook Park,et al.  Modeling of the fuel injection and combustion process in a CNG direct injection engine , 2016 .

[29]  Yi Ma,et al.  Four kinds of the two-equation turbulence model's research on flow field simulation performance of DPF's porous media and swirl-type regeneration burner , 2016 .

[30]  Choongsik Bae,et al.  The operation characteristics of a liquefied petroleum gas (LPG) spark-ignition free piston engine , 2016 .

[31]  Huihua Feng,et al.  Combustion characteristics analysis of a free-piston engine generator coupling with dynamic and scavenging , 2016 .

[32]  R. Mikalsen,et al.  A review of free-piston engine history and applications , 2007 .

[33]  Ocktaeck Lim,et al.  The effects of key parameters on the transition from SI combustion to HCCI combustion in a two-stroke free piston linear engine , 2015 .

[34]  Ocktaeck Lim,et al.  A review of free-piston linear engines , 2016 .