Design And Overall Performance Experimental Research On Free-piston Stirling Cryocooler

As an important part in the field of cryocooler,stirling cryocooler has been developed rapidly in theoretical research and practical application due to its advantages of miniaturization,flexible applicability,stable system performance,fast cooling speed and high refrigeration efficiency.In particular,the development of Free-piston Stirling Cryocooler Technology is the most prominent.This paper focused on the design and analysis of a Free-piston Stirling Cryocooler,and studied the thermodynamic cycle characteristics of the whole machine on this basis.The cooling performance of the cryocooler was further analyzed by studying the changing laws of the thermodynamic parameters.The main research contents of this article are:(1)Based on the rational parameter selection design,the two parts of the dynamic magnetic linear compressor and the Stirling refrigeration expander was designed.The dynamic magnetic linear compressor system mainly consists of three parts: compressor structure,magnetic circuit system and resonance system.The magnetic circuit system design used COMSOL software to calculate the magnetic induction intensity and distribution of magnetic field lines of permanent magnets,which was the basis for solving the force of the exciting coil in the mover magnetic field.In addition,based on the related theory of the resonance system,the structure and axial stiffness of the flexible spring for the compressor resonance system were further analyzed to explore the best working efficiency of the dynamic magnetic linear compressor under resonance.The Stirling Cryocooler expander mainly consists of regenerator,ejector piston,thin-walled cylinder,and cooling head.The design of the regenerator was completed through the determination of the packing and the optimal length-diameter ratio.The rational structural design of the ejector piston system and the determination of the fit clearance were completed according to the design requirements of the whole machine.Finally,this paper optimized the structure of the expansion cooling head and cylinder,and the reasonable design of these components was of great significance to improve the overall performance.(2)This paper used FLUENT software to analyze the thermodynamic cycle characteristics of a Free-piston Stirling Cryocooler.The distribution of the thermodynamic parameters of the whole machine was analyzed when the expander was in equilibrium.Based on this,the variation laws of the thermodynamic parameters(volume,temperature,pressure)in the compression cavity,expansion cavity,and regenerator were studied with the operation of the Free-piston Stirling Cryocooler.(3)The performance testing platform of Free-piston Stirling Cryocooler was set up to analyze the refrigeration performance parameters of the whole machine.The effects of different inflation pressures,different excitation frequencies,and different input power on the performance of the Stirling Cryocooler were analyzed.By comparing the numerical calculation results with the experimental results,the consistency of the change law between the calculated values of the performance parameters and the experimental values was obtained.The research results show that the numerical calculations were in good agreement with the experimental results.The prototype of this Free-piston Stirling Cryocooler designed in this paper has a cooling capacity of 100W@80K at the best working frequency of 20 Hz,the best inflation pressures of 2.0Mpa,and the best input power of 300 W.