Journal Published Online: 16 October 2008
Volume 5, Issue 10

Enhancement and Local Regulation of Metal Quenching Using Atomized Sprays

CODEN: JAIOAD

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.

Author Information

Alam, Umair
Otto-von-Guericke-University Magdeburg, Institute of Fluid Dynamics & Thermodynamics, Magdeburg, Germany
Krol, Jacek
Otto-von-Guericke-University Magdeburg, Institute of Fluid Dynamics & Thermodynamics, Magdeburg, Germany
Specht, Eckehard
Otto-von-Guericke-University Magdeburg, Institute of Fluid Dynamics & Thermodynamics, Magdeburg, Germany
Schmidt, Jürgen
Otto-von-Guericke-University Magdeburg, Institute of Fluid Dynamics & Thermodynamics, Magdeburg, Germany
Pages: 10
Price: $25.00
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Stock #: JAI101805
ISSN: 1546-962X
DOI: 10.1520/JAI101805