Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

BOILING AND WETTING PHENOMENA OF HOT SURFACE DURING JET IMPINGEMENT QUENCHING

Get access (open in a dialog) DOI: 10.1615/IHTC13.p28.90
12 pages

Abstrakt

Experiments were conducted to understand the phenomena that happened during jet impingement quenching of a high temperature surface. A 3mm-water-jet of 5−80K subcooling and 3−15m/s velocity was impinged on the flat surface of a cylindrical copper/steel/brass block that was preheated to 250−400°C. Sixteen thermocouples were embedded in two depths beneath the impinging surface to record the temperature response in order to predict surface temperature and surface heat flux by an inverse heat conduction technique. A high-speed video camera was employed to capture the flow behavior during quenching.
It is found that just after jet impingement, there forms a wet patch that stagnates for a certain period of time in a small central region before its front begins movement. The stagnation zone seems to be independent of jet velocity and subcooling, but dependent on the block material. During quenching, the surface heat flux varies with time and space and reaches its maximum when surface temperature drops to 150±10°C. The wetting delay (resident time) and the maximum heat flux are found to be strongly influenced by jet velocity, jet subcooling and block material. The resident time, the surface temperature at this time and the maximum heat flux values are compared with recently proposed correlations for a 2-mm water jet.