THE HEAT TRANSFER COEFFICIENT AT DISCONTINUED WATER SPRAY COOLING

1 Hrabovský Jozef
Co-authors:
1 Chabičovský Martin 1 Astrouski Ilya 1 Kotrbáček Petr
Institution:
1 Heat Transfer and Fluid Flow Laboratory, Faculty of Mechanical Engineering, VUT Brno, Brno, Czech Republic, EU, hrabovsky@fme.vutbr.cz
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
103-108
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
76 views / 31 downloads
Abstract

Cooling by water sprays is widely used in heat treatment and other metallurgical processes to control the process temperature. Water spray cooling is used statically (without movement of the spray nozzles relative to the cooled object) or dynamically (with the movement). The static regime is typical for quenching systems intended for heat treatment of fixed steel plates. The dynamic regime is used in steel treatment processes such as rolling and finishing in mills. The movement of the steel plate relative to the fixed cooling section causes non-homogeneous distribution of water on the surface of the steel plate. The variability of the cooling section length, position of water nozzles and non-homogeneity of water distribution lead to non-uniform and distorted cooling conditions. Thus it is an important issue to define the impact of these parameters on cooling intensity and the heat transfer coefficient during the cooling process of steel plates. Heat treatment of high-temperature steel is held without protective atmosphere and is accompanied by growth of different oxides on the steel plate surface as well. The layer of oxides significantly affects the cooling regime and intensity. The influence of the oxide scales on the cooling intensity was studied experimentally and by numerical modeling for different cooling regimes. Experiments were conducted for static and dynamic regimes on surfaces with different rate of oxides layer. Prepared numerical analysis simulates the process with different conditions of the cooling section and samples with different oxide scale layers. Results obtained by numerical simulation approved the impact of the oxide layer on the cooling intensity and shown different character in the static and the dynamic regime.

Keywords: Numerical simulation, heat flux, heat transfer coefficient, oxide layer, water spray cooling

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