Study on the inertance tube and double-inlet phase shifting modes in pulse tube refrigerators

The double-inlet valve and inertance tube are the two main phase shifters of pulse tube refrigerators. They are crucial for the pulse tube refrigerators to obtain an appropriate phase relationship between pressure and mass flow. In the past decades, much attention has been given to understand the separate functions of the two phase shifters, and the present work will try to investigate their coupling functions. In this paper, the influence of the double-inlet valve on the cooling performance and characteristics of inertance tubes are numerically studied at first. Then an experimental setup is built to prove the numerical results. Based on the numerical and experimental study, it is concluded that the inertance tube cannot provide the optimum impedance for those pulse tube refrigerators with small cooling power because of turbulent flow. In such case, the double-inlet valve can help to provide a better impedance and further improve the cooling performance. On the other hand, the inertance tube can provide the optimum impedance for those pulse tube refrigerators with large cooling power and the double-inlet is not necessary in such a case.