Study On A Split Free Piston Stirling Engine

As the decreasing of renewable energy resource and the growingenvironmental damage, low carbon、 energy conservation and environmentalprotection has become the consensus of the international community. As anenvironmental protection engine, stirling engine not only can use solar energy butalso industrial waste gas’s heat, so it has theoretical significance and practicalvalue for studying the working process of stirling engineThis thesis designed a split free piston stirling engine (SFPSE) according tothe project’s request. The charge inside heat cylinder is heated when sunlightconcentrated on the heating plate’s surface through the Fresnel lens. The chargeinside cool cylinder is cooled by using air blowing through cold cylinder’s wall.After the piston-system vibrates stably, the induced electromotive force is producedby the reciprocating motion of the magnet irons embedded in the power pistonwhen they cut the coils outside the irons，in this way it can output electric power.The relationship between regenerator efficiency, dead volume ratio, reversiblecoefficient, temperature difference of hot and cold ends and thermal efficiency hadbeen analyzed in Matlab environment. On account of regenerator flow resistance,SFPSE dynamic model coupling with electromagnetic in simulink environment hadbeen established to study on the dynamic performance of SFPSE.Research shows that the increase of dead volume and irreversibility (reducereversible coefficient Rs) would reduce net work and the thermal efficiency. Inorder to obtain high thermal efficiency, the aim is perfecting regenerator efficiency.The stirling engine can still work normally without regenerator, but only can getlower thermal efficiency. From controllable point of view, the reversible coefficienthas maximum impact on regenerator. This SFPSE has threshold value ofdisplacer-power piston mass ratio. The mass of power piston is of much moreeffective on the vibration frequency than displacer piston mass, hot-endtemperature and two stiffness coefficients. Because the influence of gas springstiffness coefficient in this SFPSE is much bigger than mechanical spring stiffnesscoefficient, so the mechanical spring stiffness coefficient is of least effective on thevibration frequency. This paper established a physical model of SFPSE’s regenerator, which isbased on thermodynamics theory of variable mass system with discrete analysis andboundary treatment. According to designed regenerator’s structural size and initialboundary conditions, the internal thermodynamic distribution of regenerator onrelative crankshaft angle was calculated by program with C language in whichdynamics simulation results had been taken.