Joule-Thomson valves for small cryocoolers have throttling passages on the order of 0.1 millimeter in diameter. Consequently, they can become plugged easily and stop the operation of the cooler. Plugging can be caused by solid particles, liquids or gases. Plugging is usually caused by the freezing of contaminant gases from the process stream. In small open loop coolers and in closed loop coolers where periodic maintenance is allowed, the problem is overcome by using careful assembly techniques, pure process gases, warm filters and cold adsorbers. A more thorough approach is required for closed loop cryocoolers which must operate unattended for long periods. This paper presents the results of an effort to solve this problem. The causes of plugging are examined, and various ways to eliminate plugging are discussed. Finally, the development of a 'J-T defroster' is explained. We conclude that a combination of preventive measures and a defroster will reduce the chance of cooler failure by plugging to such a degree that J-T coolers can be used for long term space missions.


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    Title :

    Joule-Thomson valves for long term service in space cryocoolers


    Additional title:

    Joule-Thomson Ventile fuer Kaeltemaschinen fuer den Langzeiteinsatz in der Raumfahrt


    Contributors:
    Lester, J.M. (author) / Benedict, B. (author)

    Published in:

    Proc. of the 3rd Cryocooler Conf., NBS ; NBSSP698 , Mai ; 257-266


    Publication date :

    1985


    Size :

    10 Seiten, 5 Bilder, 1 Quelle


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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