scholarly journals An experimental investigation of the effect of coating on heat transfer during quenching

2021 ◽  
Vol 2057 (1) ◽  
pp. 012053
Author(s):  
I A Molotova ◽  
A R Zabirov ◽  
V V Yagov ◽  
M M Vinogradov ◽  
N N Antonov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Nickel Coating ◽  
Film Boiling ◽  
Porous Nickel ◽  
Cooling Process ◽  
Steel Cylinder ◽  
Stainless Steel Cylinder ◽  
Cooling Intensity ◽  
Polished Stainless Steel

Abstract The work is aimed at studying the effect of galvanic nickel coating of a stainless steel cylinder on the quenching. In order to compare the results, the polished stainless steel cylinder was used as a sample. In addition, the influence of the formation of an oxide layer on the cooling process was studied. The experiments were carried out in water and ethanol with different subcoolings. The oxidized porous nickel coating led to increasing of the transition temperature from stable film boiling to intensive boiling regime. It was especially noticeable for cooling in water at high subcooling due to the higher cooling intensity caused by vapour layer thinning.

scholarly journals Wetting layer evolution and interfacial heat transfer in water-air spray cooling process of hot metallic surface

2021 ◽  
pp. 318-318
Author(s):  
Lidan Ning ◽  
Liping Zou ◽  
Zhichao Li ◽  
Huiping Li
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nucleate Boiling ◽  
Spray Cooling ◽  
Film Boiling ◽  
Metallic Surface ◽  
Interfacial Heat Transfer Coefficient ◽  
Interfacial Heat Transfer ◽  
Cooling Process ◽  
Inverse Heat Transfer

Spray cooling experiments on the hot metallic surfaces with different initial temperatures were performed. This paper adopts a self-developing program which is based on the inverse heat transfer algorithm to solve the interfacial heat transfer coefficient and heat flux. The temperature-dependent interfacial heat transfer mechanism of water-air spray cooling is explored according to the wetting layer evolution taken by a high-speed camera and the surface cooling curves attained by the inverse heat transfer algorithm. Film boiling, transition boiling, and nucleate boiling stages can be noticed during spray cooling process of hot metallic surface. When the cooled surface?s temperature drops to approximately 369?C - 424?C; the cooling process transfers into the transition boiling stage from the film boiling stage. The wetting regime begins to appear on the cooled surface, the interfacial heat transfer coefficient and heat flux begin to increase significantly. When the cooled surface?s temperature drops to approximately 217?C - 280?C, the cooling process transfers into the nucleate boiling stage. The cooled surface was covered by a liquid film, and the heat flux begins to decrease significantly.

scholarly journals RESEARCH ON MAXIMIZING CRITICAL AND REDUCING INITIAL HEAT FLUX DENSITIES TO ELIMINATE ANY FILM BOILING AND MINIMIZE DISTORTION DURING QUENCHING

2017 ◽  
Vol 4 ◽  
pp. 33-41 ◽  
Author(s):  
Nikolai Kobasko ◽  
Anatolii Moskalenko ◽  
Petro Lohvynenko ◽  
Volodymyr Dobryvechir
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Film Boiling ◽  
International Database ◽  
Transfer Coefficients ◽  
Mineral Oils ◽  
Heat Transfer Coefficients ◽  
Cooling Intensity ◽  
Initial Heat

In the paper the results of testing three types of FUCHS oils: Thermisol QH 120, Thermisol QH 10 and Thermisol QB 46 are discussed. The main attention is paid to critical heat flux densities evaluation because they create a basis for optimizing cooling intensity of any liquid quenchant. In the paper is underlined that any film boiling during quenching is undesirable since it is a reason for big distortion and non-uniform surface harness. It is shown that intensive quenching decreases distortion of steel parts during quenching. To eliminate film boiling during quenching in mineral oils, optimal temperature of oil should be chosen which maximize the first critical heat flux density and special additives should be used to decrease initial heat flux by creating surface micro-coating. Along with the evaluation of heat transfer coefficients, critical heat flux densities inherent to liquid quenchant must be measured first to optimize quenching processes. International DATABASE on cooling characteristics of liquid quenchants must include critical heat flux densities, initial heat flux densities, and heat transfer coefficients allowing optimizing and governing quenching processes.

scholarly journals Efficacy of Spinosad and Standards for Control of Small Black Cutworm Larvae, 1997

1998 ◽  
Vol 23 (1) ◽  
pp. 317-317
Author(s):  
D. J. Shetlar ◽  
K. McClure ◽  
H. D. Niemczyk
Keyword(s):  
Stainless Steel ◽  
Creeping Bentgrass ◽  
Steel Cylinder ◽  
Black Cutworm ◽  
Stainless Steel Cylinder ◽  
Dishwashing Detergent ◽  
Research And Education

Abstract The study was located on bentgrass range 1 north at the Ohio State Turfgrass Research and Education Center, Columbus, OH. Treatments were applied on 19 Aug to plots 4 X 6 ft arranged in a RCB, replicated 4 times. Liquid treatments were applied using a CO2 sprayer calibrated to deliver 2.0 gal/1000ft2. No immediate posttreatment irrigation was applied. The 100% creeping bentgrass range was mowed at 0.5 inch, had no thatch and was irrigated daily with 0.25 inch of water between (05:00 and 06:00). On 19 Aug, one 8-inch stainless steel cylinder was driven into the turf, about 2 hr after the last spraying to allow for complete drying of all treatments. Each cylinder was infested with eight 3rd- and 4th-instar BCW (0.375 to 0.5 inch) and covered with nylon screen. On 22 Aug (3 DAT) the covers were removed and each cylinder was flooded with a soapy water mix (15 ml Joy dishwashing detergent in 1.0 gal water) to flush out any live BCW.

The Reality of Perception: Demonstrable Effects of Perceived Risk in Goiania, Brazil

1988 ◽  
Vol 10 (3-4) ◽  
pp. 8-12 ◽  
Author(s):  
John Petterson
Keyword(s):  
Stainless Steel ◽  
Cancer Patients ◽  
Perceived Risk ◽  
Scrap Metal ◽  
Luminescent Material ◽  
Steel Cylinder ◽  
Stainless Steel Cylinder ◽  
Brazilian State ◽  
The City

On September 13, 1987, two metal and paper scavengers of the city of Goiania (pop. 1,000,000), in the central Brazilian state of Goias (pop. 13,000,000) entered an abandoned clinic in search of scrap metal. They discovered a 400-kilograrn machine that had been used to treat cancer patients with controlled doses of radiation. They dismantled the device and extracted a stainless steel cylinder; then they took the cylinder to a junkyard, broke it open with a sledge hammer, and removed a one-cubic-inch platinum capsule. Subsequently they sawed open the capsule, revealing approximately 100 grams of luminescent material, which was described by witnesses as "carnival glitter."

Spray Cooling Unit for Heat Treatment of Stainless Steel Sheets

2014 ◽  
Vol 936 ◽  
pp. 1720-1724
Author(s):  
Milan Hnizdil ◽  
Martin Chabicovsky ◽  
Miroslav Raudenský ◽  
Eric Magadoux ◽  
Florent Code
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Spray Cooling ◽  
Laboratory Measurements ◽  
Steel Sheets ◽  
Cooling Unit ◽  
Cooling Intensity ◽  
The Heat Transfer Coefficient

Stainless steel sheets are successively heated to a temperature of 1150°C and cooled until ambient temperature during the production process. Requirements for high cooling rates of stainless steel sheets producers lead to use water as a cooling medium. The information about cooling intensity (heat transfer coefficient) of different nozzles configurations is necessary for designing cooling sections. Although many researchers deal with water spray cooling, actually a general correlation for predicting heat transfer coefficient for wide range of nozzles configurations does not exists. That is the reason why heat transfer coefficient for different nozzles configurations can be only obtained by laboratory measurements. Heat transfer coefficient is mostly influenced by water impingement density and impact velocity. However other factors e.g. water temperature and velocity of the sheet can influence the heat transfer coefficient. Optimized design of the cooling unit with high cooling intensity and low water consumption was achieved by appropriate choice of these parameters. The moving experimental sheet was cooled from a temperature of 900°C to a temperature of 50°C with various configurations of nozzles. The tests shown that heat transfer coefficient was increasing with water impingement density and impact velocity. Increasing water temperature from 20 °C to 80 °C caused a decrease of the heat transfer coefficient and Leidenfrost temperature. The effect of velocity is negligible when velocities are between 25 and 100 m/min. The cooling unit was designed according to laboratory measurements to fulfill the stainless steel producer's requirements. The measurements which were done in an industrial plant confirmed the accuracy of heat transfer coefficient obtained in the laboratory. The maximum difference between laboratory and plant measurements was 15%.

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