Investigation on thermal coupled three stage pulse tube cryocooler

Abstract

Pulse Tube Cryocoolers (PTCs) have been investigated in recent times with the focus on achieving much lower temperature and reliable operation. Lower temperatures can be obtained by cascading the stages of the PTC. These stages can either be gas coupled or thermal coupled. This paper presents the design and development of two different configurations of three stage thermal coupled PTC, one with room temperature phase shifting mechanism (PSM) and the other with cold phase shifting mechanism. For room temperature PSM, the first and second stage are provided with inertance tube, while that for the third stage is provided with inertance tube and a double inlet valve. For the cold PSM, only an inertance tube is used as a phase shifter. In case of PTC with room temperature PSM, a minimum temperature of 19.61 K is achieved with a refrigerating effect of 220 mW at 30 K at the cold end of the third stage pulse tube, with an input power of 600 W. While for the PTC with cold PSM, a minimum temperature of 32.41 K is achieved. A reliability test is carried out; the PTC performed well during the entire operation and the repeatability is established.