Numerical simulation on Stirling cryocooler with mixed-packing regenerator at liquid nitrogen temperatures
The free piston Stirling cryocooler has the characteristics of wide temperature range,high refrigeration efficiency,compact structure,low vibration and long service life.The regenerator,as the core component,determines the cooling perform-ance of the cryocooler.In order to improve the efficiency of the Stirling refrigerator at liquid nitrogen temperatures range,a mixed regenerator with coiled polyimide film and stainless steel wire mesh was proposed and studied by numerical simulation.Firstly,the filling parameters of the mixed regenerator in the liquid nitrogen temperature were analyzed.Then,the geometric parameters of the cryocooler were designed and a numerical model of the entire cryocooler was established.Finally,the performance of the mixed-packing regenerator was calculated and studied as a function of the length of the regenerator,the proportion of two types of matrices filled,and the phase angle of the displacer piston.The results were compared with single-packing regenerator.The results show that the mixed-packing regenerator has obvious advantages at liquid nitrogen temperatures.The optimal refrigera-tion performance was achieved when the length of the mixed-packing regenerator is 8 cm,the filling ratio of the coiled polyimide film and the stainless steel wire mesh is 7:1,and the displacer piston is 60° ahead of the power piston.At room temperature of 300 K and input sound acoustic of 451 W,a cooling capacity of 58.1 W is obtained at 77 K,and the relative Carnot efficiency of the sound acoustic is 37.26％,which is 6.26％and 17.33％higher than the regenerator filled with single wrapped polyimide film and stainless steel wire mesh,respectively.
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