Abstract
The so-called shuttle loss in a displacer-type cryocooler is caused by temperature distribution in the radial direction of the thin gas layer between the cylinder and the displacer. The temperature oscillation is due to the following two reasons: one is reciprocating motion of the displacer and the other is pressure oscillation of the gas. We refer to the heat loss induced only by the former as the shuttle heat transfer. To evaluate the shuttle loss in a Gifford-McMahon (GM) refrigerator including the influence of the pressure oscillation, we have employed a numerical approach based on the linearized thermoacoustic theory. The theory can be a very useful tool to treat the problem if the oscillating amplitude is fractional. The results show that the pressure oscillation of the gas functions as a prime mover in usual operating conditions. Compared with the shuttle heattransfer characteristics, several characteristics of the shuttle loss were drawn from the calculation results. Further, it is confirmed that coating on the surface of the solid walls with a low thermal-conductivity material is effective in reducing the shuttle loss.
