Basic Research On The Performance Of A Free Piston Linear Alternator

In recent years, by realizing the crisis of global warming and shortage of fossil fuels,more and more people begin to pay attention to exploring new energy conversion devicesand environmental friendly fuels. Under the situation, the Free-Piston Linear Alternator(referred to as FPLA) slowly go into the people's vision. It consists of two parts. One is thefree piston linear engine, which contains dual opposed pistons connected by a connectingrod and two relevant cylinders. The other is the linear alternator with the permanentmagnet mounted on the connecting rod as the translator. The combustion occursalternately in each cylinder, making the connecting rod move back and forth. Themagnetic flux linked with circular wound coil changes periodically to produce the current.Compared with the traditional internal combustion engine,the Free-Piston LinearAlternator mainly has the following advantages: First, the Free-Piston Linear Alternatorhas no the very parts like crank connecting bar and the camshaft, thus making the overallstructure of Free-Piston Linear Alternator very simple, and the metal consumption todesign it small;what's more important,the cost to design a Free-Piston Linear Alternator isquite low. Second,the Free-Piston Linear Alternator adopts the opposed pistonmechanism,whose balance performance is superior to the traditional internal combustionengine. Also the Free-Piston Linear Alternator makes little noise when running; thefriction between the piston and the cylinder is small as the piston repeats linear motion ,and the energy loss during the convertion is small which makes the mechanical efficiencyvery high and the lifetime of the engine longer than before.Third,the compression ratio ofFree-Piston Linear Alternator can be adjusted,so the fuel adaptability is wider, not onlyheavy fuel,light fuel can be used but also other fuels can be used. The main content of thisthesis could fall into 4 parts as the followings. (1) The main structure of FPLA prototype designed by us was described at first. Then,the way that the main subsystems of FPLA cooperated with each other was explained indetail.(2) Ignition process analysis has been given and related mathematical model has beenbuilt up. Based on these, the ignition process of FPLA was simulated. At last, the designscheme toward ignition system was stated.(3) The starting process of FPLA was analysed and its mathematical model has beenbuilt up. Then the simulation for the starting process was made. We can get relatedperformance parameters from the simulation. Based on these, the starting system designplan was also stated.(4) In the simulation part, Wiebe function and thermodynamic model was establishedto analyse the dynamical properties of FPLA. Through this some conclusions were made,which can provide some suggestions for further research on FPLA. In the experiment part,some experiments were did to test the inflammability limit of LPG and what the effect iswhen the air-fuel, ignition time, the mass of the pistons have changed. The results wouldbe compared with the simulation and some conclusions were made at last.