Shuttle Loss in Pulse Tubes

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Shuttle Loss in Pulse Tubes

Yang, L. W.

Abstract Pulse tube refrigerators have the unique feature of a hollow tube replacing the cold piston. This paper analyzes some losses resulting from this hollow tube due to the oscillating flow; the losses are quite similar to the shuttle loss and pumping loss in a Stirling or G-M refrigerator. The analysis starts with surface heat pumping in a basic-type pulse tube cooler. Then, flow features and the origin of losses are further explained. As an important parameter, boundary layer thickness is predicted. The analysis shows that, due to the large temperature difference, the distribution of boundary layer thickness along the pulse tube changes greatly. For different boundary layer thicknesses, shuttle losses and pumping losses differ significantly. With the predicted boundary layer thickness, the amplitude of the shuttle loss and pumping loss are just the opposite of what they are in a traditional Stirling or G-M cooler. Pumping gas loss becomes an important loss in the pulse tube refrigerator.