Enhancement and Local Regulation of Metal Quenching Using Atomized Sprays

    Volume 5, Issue 10 (November 2008)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 16 October 2008

    Page Count: 10


    Alam, Umair
    Otto-von-Guericke-University Magdeburg, Institute of Fluid Dynamics & Thermodynamics, Magdeburg,

    Krol, Jacek
    Otto-von-Guericke-University Magdeburg, Institute of Fluid Dynamics & Thermodynamics, Magdeburg,

    Specht, Eckehard
    Otto-von-Guericke-University Magdeburg, Institute of Fluid Dynamics & Thermodynamics, Magdeburg,

    Schmidt, Jürgen
    Otto-von-Guericke-University Magdeburg, Institute of Fluid Dynamics & Thermodynamics, Magdeburg,

    (Received 15 April 2008; accepted 16 September 2008)

    Abstract

    In atomized spray quenching, the spraying water is atomized into fine droplets of the size of about 20 μm by compressed air and sprayed onto a hot surface. Only single droplets touch the surface, become deformed, and transfer heat. The drops partially evaporate and then move away from the superposed airflow. Thus, the vapor film is avoided as it is the case for other quenching techniques. It is demonstrated that the unintended collapses of the vapor film (Leidenfrost problem) at edges, corners, roughness peaks, etc., is eliminated by this technique. In this way, mass lumped regions of work pieces can be cooled more intensively than the edges. Consequently, a uniform temperature distribution with reduced thermal stresses can be obtained. The heat transfer was measured by infrared thermography. One side of the metallic sheet of 3 mm thickness was quenched by atomized spray and the surface temperature was measured on other side by an IR camera. The heat transfer coefficient is mainly determined by the impingement density. Heat transfer coefficient of 10,000 W/m2/K can be achieved within film boiling regime. This value is about three times higher than that of conventional spray quenching.


    Paper ID: JAI101805

    DOI: 10.1520/JAI101805

    ASTM International is a member of CrossRef.

    Author
    Title Enhancement and Local Regulation of Metal Quenching Using Atomized Sprays
    Symposium , 0000-00-00
    Committee A01