Study on the effect of Weber Number to heat transfer of multiple droplets on hot stainless steel surface

Multiple droplets are drops of water that continuously dropped onto a surface. Spray cooling is an application of the use of droplet on a cooling system. Spray cooling is usually used in a cooling system of electronic devices, and material quenching. In this study, correlations between Weber number and surface temperature decrease rate during multiple droplets impingement are investigated and analyzed. Visualization process is used to help determine the evaporation time of droplets impingement by using high speed camera. Induction stove is used to maintain a stainless steel surface temperature at 120°C, 140°C, and 160°C. The Weber number was varied at 15, and 52.5 to simulate low and medium Weber number. The result of this study shows that increase in Weber number does not increase the temperature decrease rate noticeably. Whereas the Weber number decrease the time required for surface temperature to reach its lowest surface temperature. It was also found that for low and medium Weber number, Weber number affect the evaporation time of multiple droplets after impingement.

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Splat Solidification of Tin Droplets

Thermal Spray 1996: Proceedings from the National Thermal Spray Conference ◽

10.31399/asm.cp.itsc1996p0657 ◽

1996 ◽

Author(s):

R. Bhola ◽

S. Chandra

Keyword(s):

Experimental Study ◽

Stainless Steel ◽

Simple Model ◽

Surface Temperature ◽

Steel Surface ◽

Liquid Droplet ◽

Contact Angles ◽

Stainless Steel Surface ◽

Splat Solidification ◽

The Impact

Abstract An experimental study was done of the impact and solidification of tin droplets falling on a stainless steel surface. The surface temperature was varied from 25°C to 240°C. Measurements were made of droplet diameters and contact angles during droplet spread. At a surface temperature of 240°C there was no solidification, and a simple model of liquid droplet impact successfully predicted the extent of droplet spread. Droplets impacting on surfaces at 25°C and 150°C solidified before spreading was complete.

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Deposition of Cobalt-60 on the Stainless-Steel Surface Used for the Primary Cooling System of a Boiling Water Reactor

Nuclear Science and Engineering ◽

10.13182/nse81-a18963 ◽

1981 ◽

Vol 77 (4) ◽

pp. 496-501 ◽

Cited By ~ 16

Author(s):

Shunsuke Uchida ◽

Masao Kitamura ◽

Yasunori Matsushima ◽

Koichi Yonezawa ◽

Katsumi Ohsumi ◽

...

Keyword(s):

Stainless Steel ◽

Steel Surface ◽

Cooling System ◽

Boiling Water ◽

Boiling Water Reactor ◽

Stainless Steel Surface ◽

Water Reactor

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On the collision of a droplet with a solid surface

Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences ◽

10.1098/rspa.1991.0002 ◽

1991 ◽

Vol 432 (1884) ◽

pp. 13-41 ◽

Cited By ~ 620

Keyword(s):

Stainless Steel ◽

Surface Temperature ◽

Liquid Film ◽

Steel Surface ◽

Ambient Pressure ◽

Early Period ◽

Metallic Surface ◽

Stainless Steel Surface ◽

Droplet Shape ◽

The Impact

The collision dynamics of a liquid droplet on a solid metallic surface were studied using a flash photographic method. The intent was to provide clear images of the droplet structure during the deformation process. The ambient pressure (0.101 MPa), surface material (polished stainless steel), initial droplet diameter (about 1.5 mm), liquid (n-heptane) and impact Weber number (43) were fixed. The primary parameter was the surface temperature, which ranged from 24°C to above the Leidenfrost temperature of the liquid. Experiments were also performed on a droplet impacting a surface on which there existed a liquid film created by deposition of a prior droplet. The evolution of wetted area and spreading rate, both of a droplet on a stainless steel surface and of a droplet spreading over a thin liquid film, were found to be independent of surface temperature during the early period of impact. This result was attributed to negligible surface tension and viscous effects, and in consequence the measurements made during the early period of the impact process were in good agreement with previously published analyses which neglected these effects. A single bubble was observed to form within the droplet during impact at low temperatures. As surface temperature was increased the population of bubbles within the droplet also increased because of progressive activation of nucleation sites on the stainless steel surface. At surface temperatures near to the boiling point of heptane, a spoke-like cellular structure in the liquid was created during the spreading process by coalescence of a ring of bubbles that had formed within the droplet. At higher temperatures, but below the Leidenfrost point, numerous bubbles appeared within the droplet, yet the overall droplet shape, particularly in the early stages of impact (< 0.8 ms), was unaffected by the presence of these bubbles. The maximum value of the diameter of liquid which spreads on the surface is shown to agree with predictions from a simplified model.

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