Theoretical Analysis on the Influence of the Cold end Connecting Tube in a U-type Pulse Tube Cryocooler

For the aerospace applications,U-type pulse tube cryocoolers (UPTC)can improvethe temperature uniformityand thestructure stability of the cold end.However,theinfluence of the cold endconnecting tube on the performance ofa UPTC is inevitable and the mechanism of the influencehasn’t been well understood.A simplified model of the cold end ofa UPTCis developedin this study. With this model, the periodical thermodynamic processesand movement of the gas parcels areachieved. With the thermodynamic properties of the gas parcels, the influence of the cold end connecting tube is analyzed and quantified. The resultsdemonstrate the disadvantageousinfluenceof the cold endconnecting tube ona UPTC.Moreover,the critical length ofthe cold endconnectingtube is mentionedfora UPTC. Within the critical length, theinfluence of the cold end connecting tube is discussedfrom several aspects such as the length, the heat convection, the temperature difference.