dry-outs two different kinds can occur in gravity-assist heat pipes with capillary flow. An exess of hydrostatic driving force can lead to a receding of the menisci into the capillary structure and an 'azimuthal dry-out' characterized by a concentration of the circumference of the heat pipe. The azimuthal dry-out most likely occurs during start-up and disappears at higher heat fluxes. It can be prevented by using a graded capillary structure or a homogeneous capillary structure with a static capillary rise, which exeeds the highest point of the evaporator. A lack of hydrostatic driving force, on the other hand, leads to an 'axial dryout', which is characterized by a lack of axial liquid pool at the bottom, the reaching of the axial dry-out limit in the capillary flow mode will manifest itself as the beginning of a pool transfer and an eventual transition to a new stationary state with mixed capillary- and free flow. The basic equation for the axial dry-out is derived and resoved for a simple case. The role of inertia forces and entrainment is pointed out.


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    Title :

    The dry-out limits of gravity- assist heat pipes with capillary flow


    Additional title:

    Austrocknungsgrenze fuer schwerkraftbetriebene Waermeleitrohre mit Kapillarstroemung


    Contributors:
    Busse, C.A. (author) / Kemme, J.E. (author)


    Publication date :

    1978


    Size :

    8 Seiten, 5 Bilder, 8 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English





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