Numerical Algorithm And Optimization Of Efficiency In An Alpha-type Stirling Engine

Stirling engine is an environmentally-friendly and reliable power machine of high thermal efficiency, compact structure, great adaptability to many kinds of heat source, at the background that the energy problem is increasingly severe recently, more and more attention has been paid to stirling engine. As an important equipment to solve the problems of environment and energy, Stirling engine has become a hot research topic in the present stage.The development of Stirling engine and its analysis method was introduced briefly and the development and the thoughts and methods of Stirling engine simulation were presented in detail. The main work in this thesis was to optimize the operational parameters of the Stirling engine. Based on the ideal model of adiabatic equations, how the Stirling cycle works was simulated through Runge Kutta method. Moreover, the ideal adiabatic model is modified by KL equations. Heat transfer and pressure drop of heat exchangers in the Stirling engine was considered and the operation conditions of the Stirling engine were simulated comprehensively. The results showed that the sweep gas volume ratio of expansion chamber and compression chamber has a relatively large impact on the thermal efficiency and thermal efficiency will not be raised with the increase of volume ratio monotonically. There is a most suitable volume ratio in which the thermal efficiency reaches its peak in certain working condition. Besides, on the base of the modified ideal adiabatic model, how the phase difference of swept volume changes in the expansion chamber and compression chamber and the difference of temperature of heat and cool sources affect thermal efficiency in Stirling engine was analyzed. There is also a best temperature difference that maximizes the thermal efficiency. On the foundation of simulation, the specific factors that affect the operating conditions were searched and calculated by genetic algorithm and the best volume ratio, temperature ratio and phase difference were obtained and compared under different working conditions. This thesis combined the ideal adiabatic model, the heat and mass transfer equation and the genetic optimization algorithm and provided new ideas for the optimal design of the Stirling engine.