A method for measuring steady local heat transfer to an impinging liquid jet

Vader, D.T.; Incropera, F. P.; Viskanta, R.

doi:10.1016/0894-1777(91)90016-k

Cited by 22 publications

(12 citation statements)

References 14 publications

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“…High roughness of a nozzle hole surface caused by the formation of the scale promotes a turbulent flow of cooling water jet passing through the nozzles and obstructs the preservation of a laminar flow state of water jet. In the cooling process of hot strip mill, a small cross section and a high speed of water jet arising from the preservation of a laminar flow state enable a high‐pressure impingement to be transferred to the cooling‐aimed strips . The scale could obstruct a laminar flow of cooling water and become a cause of nozzle blogging, resulting in the serious deterioration of products due to diminution of cooling efficiency.…”

Section: Introductionsupporting

confidence: 85%

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Formation of a scale on the hole surface of cooling nozzles in the hot strip mill process, obstructing a laminar flow of coolant

Huh

Park

Jung

et al. 2012

Surface & Interface Analysis

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We investigated on the formation of a scale on the hole surface of brass cooling nozzles in the hot strip mill process of steel manufacturing. High roughness of a nozzle hole surface due to the scale formation obstructs a laminar flow of coolant, which can result in the diminution of cooling efficiency of strips. Morphology and elemental composition of a scale formed on the hole surface of cooling nozzles used in the hot strip mill process for a long time were characterized with an electron microscope equipped with an energy dispersive X‐ray spectroscope. The scale is mainly composed of a foreign substance layer and an oxide layer. In addition, three kinds of cooling water were analyzed to investigate an inflow source for elemental constituents of the foreign substance layer. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Introductionsupporting

confidence: 85%

“…From this result, it can be inferred that a scale has been formed on the hole surface of the long time used nozzle. High roughness with a big height difference is one of factors of reducing cooling efficiency of products by obstructing a laminar flow of cooling water …”

Section: Resultsmentioning

confidence: 99%

Formation of a scale on the hole surface of cooling nozzles in the hot strip mill process, obstructing a laminar flow of coolant

Huh

Park

Jung

et al. 2012

Surface & Interface Analysis

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“…The temperature profile was assumed to be steady in the coordinate system. Equation (1) was solved numerically by using the finite volume approximation developed by Vader et al 7) A rectangular computer domain with a length of 79.1 mm, width of 50.9 mm, and thickness of 0.3 mm was divided into 140 × 90 × 200 cells in the x-, y-, and z-directions. The material properties were given by the network database system for thermophysical property data provided by National Institute of Advanced Industrial Science and Technology (AIST) in Japan.…”

Section: Methodsmentioning

confidence: 99%

Heat Transfer Characteristics of a Pipe-laminar Jet Impinging on a Moving Hot Solid

et al. 2015

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This study experimentally investigated the hydrodynamics and heat transfer characteristics of a circular water jet impinging on a moving hot metal sheet as fundamental research on pipe-laminar cooling. The circular jet was issued from a 5-mm-diameter pipe nozzle. A 0.3-mm-thick sheet made of stainless steel was adopted as the test sheet. In the experiment, the liquid flow formed by the jet impingement was observed by flash photography, and the temperature profile on the underside of the moving sheet was measured by infrared thermography. The initial temperature of the moving solid was varied from 100°C to 500°C. The mean velocity at the nozzle exit ranged between 0.4 m/s and 1.2 m/s. The moving velocity of the solid was set to less than or equal to 1.5 m/s. The estimated heat flux profile on the cooled surface was found to be strongly dependent on the initial temperature of the sheet. When the initial temperature of the sheet was relatively low, a bow-shaped high heat flux region appeared in the upstream of the jet impact point. At higher temperatures, the heat flux area existed only in the jet impact regions. The heat flux increased with increasing initial sheet temperature, reached peak values, and then decreased drastically. The sharp decrease in the heat flux, which was due to the formation of a vapor layer, was influenced by the jet velocity and/or the sheet velocity.

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“…The local temperature distribution on the wet surface was evaluated using the method developed by Vader et al 13) Equation ( Fig. 4.…”

Section: Data Reductionmentioning

confidence: 99%

Heat Transfer Characteristics of a Circular Water Jet Impinging on a Moving Hot Solid

et al. 2014

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The heat transfer characteristics of a circular water jet impinging on a moving hot solid were investigated experimentally. In the experiments, distilled water at room temperature was used as the test coolant. The circular jet issued from a 5-mm-diameter pipe nozzle, fell vertically downward, and impinged on a horizontal moving sheet made of 0.3-mm-thick stainless steel. The initial temperature of the sheet, the jet velocity, and the moving sheet velocity were varied systematically. The initial temperature of the moving sheet was set to 100, 150, 200, or 250°C. The mean velocity at the nozzle exit was 0.4, 0.8, or 1.2 m/s, and the moving velocity was 0.5, 1.0, or 1.5 m/s. Observations made using flash photography and thermography showed that the location of the front edge of the liquid film formed upstream of the jet impact point depends on all of these factors. The local heat flux is very small in the dry area, increases steeply near the front edge of the liquid film, and reaches a peak. If the distance between the front edge of the liquid and the jet impact point is relatively large, a second peak appears near the jet impact point. An experimental correlation was developed for predicting peak heat fluxes near the front edge of the liquid, although it has no theoretical background. The correlation agrees moderately well with the experiments.

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A method for measuring steady local heat transfer to an impinging liquid jet

Cited by 22 publications

References 14 publications

Formation of a scale on the hole surface of cooling nozzles in the hot strip mill process, obstructing a laminar flow of coolant

Formation of a scale on the hole surface of cooling nozzles in the hot strip mill process, obstructing a laminar flow of coolant

Heat Transfer Characteristics of a Pipe-laminar Jet Impinging on a Moving Hot Solid

Heat Transfer Characteristics of a Circular Water Jet Impinging on a Moving Hot Solid

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