Vliv impaktního úhlu a tlaku na sprchové chlazení vertikálně se pohybujících horkých ocelových povrchů

Influence of impact angle and pressure on spray cooling of vertically moving hot steel surfaces

abstrakt

en

Cooling of vertically moving strips is used very often to obtain the required material properties. Water spray cooling has to be used when the high cooling intensity is needed. The water impacting on the strip surface is reflected and falls down between water nozzles and strip surface. This falling water has a significant influence on cooling intensity and also on cooling homogeneity. It causes undesirable problems with strip deformation and controllability of cooling. A water knife is used to reflect falling water out from the area between strip surface and water nozzles. Water knife is formed by row of flat jet nozzles has also cooling effect on the moving steel strip. This effect was studied and measured. Heat Transfer and Fluid Flow Laboratory is equipped with testing device which allows vertical movement of a heated experimental plate (sheet). Three different size of flat jet nozzles were tested with different water pressure (water flow rate) and angle of water impact (inclination angle of spraying bar). Water pressure range was between 2 and 8 bar and angle of water impact was changing from 20 to 40C. Dependence of heat transfer coefficient on surface temperature was evaluated for each experiment. Interesting results were obtained from comparison of these experiments results and showed that water pressure (flow rate) and also water impact angle has significant influence on the cooling intensity.

Publikace se zabývá vlivem orientace trysek a tlaku na sprchové chlazení vertikálně se pohybujících horkých ocelových povrchů. Tlaky vody od 2 do 8 bar a impaktní úhly od 20 deg do 40 deg byly zkoumány.

Cooling of vertically moving strips is used very often to obtain the required material properties. Water spray cooling has to be used when the high cooling intensity is needed. The water impacting on the strip surface is reflected and falls down between water nozzles and strip surface. This falling water has a significant influence on cooling intensity and also on cooling homogeneity. It causes undesirable problems with strip deformation and controllability of cooling. A water knife is used to reflect falling water out from the area between strip surface and water nozzles. Water knife is formed by row of flat jet nozzles has also cooling effect on the moving steel strip. This effect was studied and measured. Heat Transfer and Fluid Flow Laboratory is equipped with testing device which allows vertical movement of a heated experimental plate (sheet). Three different size of flat jet nozzles were tested with different water pressure (water flow rate) and angle of water impact (inclination angle of spraying bar). Water pressure range was between 2 and 8 bar and angle of water impact was changing from 20 to 40C. Dependence of heat transfer coefficient on surface temperature was evaluated for each experiment. Interesting results were obtained from comparison of these experiments results and showed that water pressure (flow rate) and also water impact angle has significant influence on the cooling intensity.

impaktní úhel, tlak, součinitel přestupu tepla

impact angle, pressure, heat transfer coefficient

13.11.2013

Institute of Metals and Technology

Ljubljana, Slovenija

978-961-92518-6-7

Program and book of abstracts, 21th Conference on Materials and Technology

21

85–85

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