Publication detail

Prediction of Leidenfrost Temperature in Spray Cooling for Continuous Casting and Heat Treatment Processes

HNÍZDIL, M. KOMÍNEK, J. LEE, T. RAUDENSKÝ, M. ČARNOGURSKÁ, M. CHABIČOVSKÝ, M.

English title

Prediction of Leidenfrost Temperature in Spray Cooling for Continuous Casting and Heat Treatment Processes

Type

journal article in Web of Science

Language

en

Original abstract

Spray cooling of hot steel surfaces is an inherent part of continuous casting and heat treatment. When we consider the temperature interval between room temperature and for instance 1000 degrees C, different boiling regimes can be observed. Spray cooling intensity rapidly changes with the surface temperature. Secondary cooling in continuous casting starts when the surface temperature is well above a thousand degrees Celsius and a film boiling regime can be observed. The cooled surface is protected from the direct impact of droplets by the vapour layer. As the surface temperature decreases, the vapour layer is less stable and for certain temperatures the vapour layer collapses, droplets reach the hot surface and heat flux suddenly jumps enormously. It is obvious that the described effect has a great effect on control of cooling. The surface temperature which indicates the sudden change in the cooling intensity is the Leidenfrost temperature. The Leidenfrost temperature in spray cooling can occur anywhere between 150 degrees C and over 1000 degrees C and depends on the character of the spray. This paper presents an experimental study and shows function for prediction of the Leidenfrost temperature based on spray parameters. Water impingement density was found to be the most important parameter. This parameter must be combined with information about droplet size and velocity to produce a good prediction of the Leidenfrost temperature.

English abstract

Spray cooling of hot steel surfaces is an inherent part of continuous casting and heat treatment. When we consider the temperature interval between room temperature and for instance 1000 degrees C, different boiling regimes can be observed. Spray cooling intensity rapidly changes with the surface temperature. Secondary cooling in continuous casting starts when the surface temperature is well above a thousand degrees Celsius and a film boiling regime can be observed. The cooled surface is protected from the direct impact of droplets by the vapour layer. As the surface temperature decreases, the vapour layer is less stable and for certain temperatures the vapour layer collapses, droplets reach the hot surface and heat flux suddenly jumps enormously. It is obvious that the described effect has a great effect on control of cooling. The surface temperature which indicates the sudden change in the cooling intensity is the Leidenfrost temperature. The Leidenfrost temperature in spray cooling can occur anywhere between 150 degrees C and over 1000 degrees C and depends on the character of the spray. This paper presents an experimental study and shows function for prediction of the Leidenfrost temperature based on spray parameters. Water impingement density was found to be the most important parameter. This parameter must be combined with information about droplet size and velocity to produce a good prediction of the Leidenfrost temperature.

Keywords in English

spray cooling; Leidenfrost temperature; continuous casting; heat treatment; mist cooling; experimental

Released

22.11.2020

Publisher

MDPI

Location

BASEL

ISSN

2075-4701

Volume

10

Number

11

Pages from–to

1–12

Pages count

12

BIBTEX


@article{BUT166111,
  author="Milan {Hnízdil} and Jan {Komínek} and Taewoo {Lee} and Miroslav {Raudenský} and Mária {Čarnogurská} and Martin {Chabičovský},
  title="Prediction of Leidenfrost Temperature in Spray Cooling for Continuous Casting and Heat Treatment Processes",
  year="2020",
  volume="10",
  number="11",
  month="November",
  pages="1--12",
  publisher="MDPI",
  address="BASEL",
  issn="2075-4701"
}