scholarly journals Effects of five different parameters on biodiesel HCCI combustion in free-piston engine generator

2021 ◽  
Vol 25 (6 Part A) ◽  
pp. 4197-4207
Author(s):  
Chunhui Liu ◽  
Shaojie Wu ◽  
Shuo Pang
Keyword(s):  
Initial Pressure ◽  
Piston Engine ◽  
Detailed Chemical Kinetics ◽  
Free Piston ◽  
Hcci Combustion ◽  
Free Piston Engine ◽  
Combustion Simulation ◽  
Working Frequency ◽  
Skeletal Mechanism ◽  
Detailed Chemical

A coupled 3-D CFD and detailed chemical kinetics model of free-piston engine generator (FPEG) was adopted to investigate the effects of initial parameters on homogeneous charge compression ignition (HCCI) combustion and emission. Biodiesel with 115 species skeletal mechanism was selected as fuel. Five different parameters, namely the initial pressure, the initial temperature, the working frequency, the compression ratio and the fuel equivalence ratio, were selected to analyze their influences in the HCCI combustion simulation of FPEG. The simulation results showed that the change of the five parameters had visible impact on the heat release rate of HCCI combustion, which caused the in-cylinder temperature and pressure to change, and also caused the emission content of NOx and SOOT to change obviously.

CFD-Based Optimization of a Diesel-fueled Free Piston Engine Prototype for Conventional and HCCI Combustion

2008 ◽  
Vol 1 (1) ◽  
pp. 1118-1143 ◽  
Author(s):  
Miriam Bergman ◽  
Jakob Fredriksson ◽  
Valeri I. Golovitchev
Keyword(s):  
Piston Engine ◽  
Free Piston ◽  
Hcci Combustion ◽  
Free Piston Engine

Numerical analysis of two-stroke free piston engine operating on HCCI combustion

2011 ◽  
Vol 88 (11) ◽  
pp. 3712-3725 ◽  
Author(s):  
Shuaiqing Xu ◽  
Yang Wang ◽  
Tao Zhu ◽  
Tao Xu ◽  
Chengjun Tao
Keyword(s):  
Numerical Analysis ◽  
Piston Engine ◽  
Free Piston ◽  
Hcci Combustion ◽  
Free Piston Engine

Study on the Motion Characteristics of a Hydraulic Free-Piston Engine

2014 ◽  
Vol 889-890 ◽  
pp. 390-393
Author(s):  
Shi Yu Li ◽  
Zhao Cheng Yuan ◽  
Jia Yi Ma
Keyword(s):  
Fuel Injection ◽  
Fuel Efficiency ◽  
Injection Timing ◽  
Piston Engine ◽  
Free Piston ◽  
Fuel Injection Timing ◽  
Free Piston Engine ◽  
Center Position ◽  
Working Frequency ◽  
Motion Characteristics

Hydraulic free-piston engines have potential advantages of cost and fuel efficiency. Due to no crankshaft system, it is difficult and important to control the piston motion and working frequency precisely. This paper studies on the motion characteristics for the hydraulic free-piston engine effects of operation parameters, and results are presented. The TDC (Top Dead Center) position and CR (Compression Ration) are great influenced by starting pressure and fuel injection timing, and working frequency is mainly influenced by piston mass, starting pressure and fuel quantity.

Realizing Trajectory-Based Combustion Control in a Hydraulic Free Piston Engine via a Fast-Response Digital Valve

2018 ◽  
Author(s):  
Chen Zhang ◽  
Zongxuan Sun
Keyword(s):  
Chemical Kinetics ◽  
Thermal Efficiency ◽  
Fast Response ◽  
Combustion Control ◽  
Piston Engine ◽  
Free Piston ◽  
Frictional Loss ◽  
Switching Strategy ◽  
Hcci Combustion ◽  
Free Piston Engine

Previously, the authors have proposed the concept of piston trajectory-based combustion control enabled by a free piston engine (FPE) and shown its advantages on both thermal efficiency and emissions performance. The main idea of this control method is to design and implement an optimal piston trajectory into FPE and optimizes the combustion performance accordingly. To realize the combustion control in practice, it is obvious that the design of the optimal trajectory should consider the dynamic behaviors of the FPE’s actuation systems as well as variable load dynamics and fuels’ chemical kinetics. In this paper, a comprehensive model describing the operation of a hydraulic FPE fueled by diesel under HCCI combustion mode is developed. Such a high fidelity model includes four parts, i.e. the piston dynamics, the hydraulic dynamics, the thermodynamics and the fuel’s chemical kinetics. Extensive simulation results are produced, showing that by varying the switching strategy of a fast-response digital valve, the hydraulic FPE can operate at different working loads in a stable manner. Additionally, analysis has been conducted to quantify the thermal efficiency as well as the frictional loss and throttling loss of the FPE. At last, a feedback control is developed to generate optimal switching strategies for the digital valve aimed to achieve the HCCI combustion phasing control. The resulted switching strategy of the digital valve not only increases the thermal efficiency by 0.76%, but also reduces frictional loss by 9.8%, throttling loss by 6.5% as well as NOx emission by 85.6%, which clearly demonstrates the effectiveness of the trajectory-based combustion control.

The Simulation of Hydraulic Free Piston Engine Fueled with DME in HCCI Mode

2012 ◽  
Vol 602-604 ◽  
pp. 1090-1094
Author(s):  
Xiao Long Li ◽  
Yang Wang ◽  
Tao Xu ◽  
Fei Yu Song ◽  
Ya Jun He ◽  
...  
Keyword(s):  
Heat Release ◽  
Three Dimensional ◽  
Simulation Models ◽  
Kinetic Mechanism ◽  
Piston Engine ◽  
Free Piston ◽  
Hcci Combustion ◽  
Free Piston Engine ◽  
Computational Fluid Dynamics Cfd ◽  
Dimensional Simulation

In order to investigate the performance of hydraulic free piston engine (HFPE) fueled with dimethyl-ether (DME) under homogeneous charge compression ignition (HCCI) combustion, one-dimensional and three-dimensional simulation models are established by AMESIM and FIRE respectively. The simulation results show that the piston’s velocity and the displacement are dissymmetric about top dead center (TDC). The residence time of piston around TDC is quite short. DME chemical reaction kinetic mechanism is applied to three-dimensional computational fluid dynamics (CFD) model. Under equivalence ratio of 0.4, boost ratio of 1.33 and EGR ratio of 0.4, three heat release peaks appears. Oxidation of CO which contributes 38% of total energy is considered as the main reason of the third heat release peak.

Influence of Piston Initial State on HCCI Combustion in Micro Free-Piston Engine Using Experiment Images and CFD Analysis

2013 ◽  
Vol 724-725 ◽  
pp. 1350-1354
Author(s):  
Jin Bai ◽  
Qian Wang ◽  
Zhi Xia He ◽  
Peng Gang Zhang
Keyword(s):  
High Speed ◽  
Ignition Time ◽  
Combustion Process ◽  
Single Shot ◽  
Piston Engine ◽  
Initial State ◽  
Propane Combustion ◽  
Free Piston ◽  
Hcci Combustion ◽  
Free Piston Engine

The visualization experimental setup of micro free-piston engine has been built, the process of single shot compression combustion in micro combustion chamber has been observed by the high-speed digital camera; Based on the propane combustion kinetics, the numerical calculation method for combustion process coupling with the free-piston movement was put forward, through editing the dynamic mesh subroutine in STAR-CD, the process of homogeneous charge compression ignition (HCCI) in the micro chamber was studied; The influence of piston initial state on HCCI combustion process was analyzed , indicating that the piston mass directly affects the homogeneous gas compression ratio, ignition time, single combustion process cycle and the changes of combustion pressure and temperature, all this research can be the basic theories for designing the micro free piston engine .

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