The Design And Experimental Research For A Pneumatically Driven Split-Stirling Cryocooler Operating At Hundred Herz Range

Applications in the aerospace field, such as the cooling of infrared detectors and optic devices, call for strict requirements on mass, volume, and fast cool-down of cryocoolers. In recent years, how to raise operating frequency in order to reduce overall mass and volume of cryocoolers while maintaining the comparable efficiency or cooling power has become a research hotspot. So far most researches focus on pulse tube cryocoolers driven by thermoacoustic engines and linear compressors. With only one driving motor, the pneumatically driven split-Stirling cryocoolers could be smaller, lighter and consume less energy, which make them very attractive in infrared technology and superconducting electronics. The method of increasing operating frequency to reduce overall mass and volume of cryocoolers is also feasible for pneumatically driven split-Stirling cryocoolers. Hence, this paper carried out the following work:1. Research status of cryocooler operating at hundred herz range of all institutes at home and abroad is systematically investigated. It’s shown that power density of compressors working at hundred herz range is much larger than that of the traditional cryocoolers (working at30-60Hz), which fully demonstrate the idea that increasing operating frequency is an effective way to reduce overall mass and volume of cryocoolers.2. Cooling capacity of pneumatically driven split-Stirling cryocoolers and the forces acting on the displacer are theoretically analyzed, expression of inherent frequency of pneumatic expander is obtained. At the same time, the influence of charging pressure on inherent frequency of pneumatic expander and compressor is discussed, and the influence of frequency on expander is investigated. Amplitude of displacer displacement and the phase difference between displacer displacement and the pressure of expansion chamber are obtained based on the motion equation of displacer by Newton’s second law. Loss mechanisms of pneumatically driven split-Stirling cryocoolers are introduced.3. Detailed introduction of physical model and modeling method of a pneumatically driven split-Stirling cryocooler operating at hundred herz range is provided, a model including all the components of the cooler is developed. Based on this, a pneumatically driven split-Stirling cryocooler operating at hundred herz range is designed.4. Experimental study on the pneumatically driven split-Stirling cryocooler is carried out. Driven by a commercial linear compressor, a no-load temperature of77.1K is reached, and0.28W cooling power at90K is obtained when operating at105Hz and2.50MPa.