Two-phase coexistence analysis of the bellows control mechanism for a J-T cryocooler

摘要

The bellows control mechanism is one of the mostcritical control elements in the Joule-Thomson cryocooler. In thecool-down process, the interior gas of the bellows may reachliquefaction temperature, cause vapour-liquid two phasecoexistence phenomena, and achieve the quick open/close controlfunction of a J-T valve. This paper establishes a transient model ofa simplified bellows mechanism, investigates the variation of thestate properties of nitrogen inside the bellows, and its effects onthe performance with different bellows stiffness in the cool-downprocess. According to the real shape and dimension, the two-phasemodel is put into a J-T cryocooler integrated model to accomplishthe J-T cryocooler system simulation. To adopt the benefit of two-phase coexistence behavior effectively, a revised initial J-T valvedesign is also proposed in this work.