A High-Efficiency 80 K Coaxial Pulse Tube Refrigerator with Both Active Phase Shifting and Work Recovery

Pulse tube refrigerator is abundantly used in military and civilian areas owing to the cold head without moving parts. The phase difference between mass flow and pressure wave in the cold finger significantly influences the efficiency of the pulse tube refrigerator. Most pulse tube refrigerators adopt passive phase shifters, such as the inertance tube, double inlet, and passive displacer, which cannot acclimate the phase difference with the variation of cooling temperature. This paper proposes a single-stage pulse tube refrigerator with high-efficiency cooling in the temperature range near 80 K by the active displacer with work recovery. By actively altering the phase difference in an extensive cooling temperature range of 80 K to 120 K, the cold finger of the refrigerator is capable of efficiently providing a considerable cooling capacity. And the active displacer with work recovery can convert the energy dissipated initially as heat into acoustic power. This part of the acoustic power enters the cold finger again to enhance efficiency. The experiment results also show that the refrigerator could provide a cooling capacity of 20 W at 80 K when the input power of the compressor is 256.6 W and 5.1 W input power of the phase shifter, and the phase shifter recovers 17 W of acoustic power concurrently, with the relative Carnot efficiency reaching 21%.