Pulse Tube Cryocooler Dynamics and Simulation

The Pulse Tube cryocooler is a relatively new device with a promising future in space grade cryogenics. Unlike many active cryocoolers, the pulse tube is a regenerative type cooler with no cold end moving parts. The lack of cold end moving parts permits it to be used in application with mechanically sensitive or high fidelity components. The pulse tube currently lacks adequate scientific literature and understandings that other space qualified cryocoolers have. A systematic approach to understand, model, and study is provided in this work. Further, the importance of a standardized convention of the dynamically complex pulse tube is elucidated to clarify conflicting accounts found in literature. Flow solutions of the pulse tube demands great conceptual understanding and are carried out though numerical simulation. A 2-D pulse tube is modeled in detail assuming axisymmetric conditions. It is found that flow initialization periods are substantially long in comparison to cycle time due to the great inertial resistance found in pulse tubes along with the large volume associated to the reservoir. During this period, the pulse tube section temperature profile is found to significantly rise prior to a refrigeration permitting profile. It is also found that porous medium (inertial) resistance coefficients can be utilized to sufficiently model long spans of inertance tubing without the need for increased computationally-demanding mesh size.