Numerical investigation on heat transfer of water spray cooling from single-phase to nucleate boiling region

2020 ◽  
Vol 151 ◽  
pp. 106258 ◽  
Author(s):  
Chang Cai ◽  
Hong Liu ◽  
Ming Jia ◽  
Hongchao Yin ◽  
Rong Xie ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Single Phase ◽  
Nucleate Boiling ◽  
Spray Cooling ◽  
Water Spray ◽  
Water Spray Cooling

Heat Transfer Associated With Air-Water Spray Cooling of Forgings From High Temperatures

2001 ◽  
Author(s):  
J. Ward ◽  
M. de Oliveira ◽  
D. R. Garwood ◽  
R. A. Wallis
Keyword(s):  
Heat Transfer ◽  
Water Flow ◽  
Gas Turbines ◽  
Spray Cooling ◽  
Solution Temperature ◽  
Air Cooling ◽  
Water Spray ◽  
Transfer Rates ◽  
Wide Range ◽  
Water Spray Cooling

Abstract The desired mechanical properties of the nickel-based or titanium forgings used in gas turbines for aircraft and power generation applications can be controlled by varying the rate of cooling from the so-called solution temperature during an initial heat treatment process. The use of dilute air-water spray cooling of these forgings is a technique which can provide heat transfer rates lying between those associated with conventional oil quenching or convective air-cooling. Air assisted atomisation can result in fine sprays over a wide range of water flow rates and it has a further advantage in that the air “sweeps” the surface and hence helps to prevent the build up of deleterious vapour films at high surface temperatures. The paper presents experimental data for the heat transfer rates associated with the use of these sprays to cool surfaces from temperatures of approximately 800°C. Many forgings contain surface recesses, which can lead to build up or “pooling” of the water so that the effect of variations in surface geometry is also reported. Periodic interruption of the water flow is a technique which can be employed to provide additional control of the heat transfer rate, particularly at temperatures below 500°C so that data is also presented for pulsed sprays.

Visual Onset of Nucleate Boiling in Water Spray Cooling on Hot Steel Plate

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Jungho Lee ◽  
Sang Gun Lee ◽  
Jinsub Kim
Keyword(s):  
Temperature Gradient ◽  
Surface Temperature ◽  
Steel Plate ◽  
Outer Zone ◽  
Nucleate Boiling ◽  
Spray Cooling ◽  
Spray Nozzle ◽  
Water Spray ◽  
Nozzle Height ◽  
Water Spray Cooling

The onset of nucleate boiling in water spray cooling on hot steel plate was investigated by a simultaneous boiling visualization and heat transfer measurement. The boiling phenomena were visualized with 4K video camera and the surface temperature of the hot steel plate was determined by solving 2-D inverse heat conduction during water spray cooling. The temperature was measured by a sampling rate of 10 data/sec. The hot steel plate was initially heated up to 900°C and the coolant temperature was kept at a constant temperature of 20°C. The spray nozzle with fullcone pattern was mounted with the three different heights (100, 200 and 300 mm). The more spray height was increased, the more scattered the spray pattern became, which could affect the partial spray intensity and overall cooling uniformity. The lower spray nozzle height of 100 mm shows the steep temperature gradient in inner zone. As the spray particles are more intense at inner zone which wets faster than outer zone. But the higher spray nozzle height of 300 mm, the temperature profile keeps constant within the 400 sec. After this time, the outer zone is wetted faster than inner zone. At the middle height of 200 mm, although the temperature gradient in inner zone is slightly higher than that in outer zone, the overall surface wetting is relatively uniform in the inner and outer zone. These results exhibit that the spray cooling uniformity can be controlled with optimized spray nozzle height. Furthermore the boiling visualization agrees well with the onset of nucleate boiling in surface temperature profiles.

Experimental Investigation on Heat Transfer of Water Spray Cooling by Addition of n-Butanol

2020 ◽  
Author(s):  
Chang Cai ◽  
Hong Liu ◽  
Han Chen ◽  
Chuanqi Zhao ◽  
Jiuliang Gao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Heat Dissipation ◽  
Absolute Error ◽  
Spray Cooling ◽  
High Heat Flux ◽  
Water Mixture ◽  
Water Spray ◽  
Maximum Absolute Error ◽  
Water Spray Cooling

Abstract Heat transfer characteristics of water spray cooling with n-butanol additive were experimentally studied in this paper. The results indicated that adding n-butanol can effectively enhance the heat dissipation and control the surface temperature. The optimal concentration of n-butanol corresponding to the best heat transfer performance is 0.5 vol%. The experimental Nusselt numbers also agree well with a previous correlation with Weber, Prandtl, Jacob and Reynolds numbers, evidenced by a maximum absolute error of 6.34%. The measurement also showed that the decrease of surface tension and contact angle of the n-butanol-water mixture is the main mechanism to enhance the spray cooling heat transfer, while other physical properties also play an important role. The surface temperature non-uniformity in the radial direction is more apparent at a high heat flux while the addition of different contents of n-butanol has a negligible effect.

scholarly journals 3D Transient Spray Cooling Heat Transfer Simulation for Metallic Slabs of Various Alloys

2020 ◽  
Vol 15 (6) ◽  
pp. 895-904
Author(s):  
Mohamed Elguerri ◽  
Farid Belfodil ◽  
Yassine El Guerri ◽  
Abdelilah Bouragba
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Spray Cooling ◽  
Water Spray ◽  
Steel Cast ◽  
Titanium Nickel ◽  
Heat Transfer Simulation ◽  
Dimensional Simulation ◽  
Heated Metal ◽  
Water Spray Cooling

Water spray cooling is widely used in many industrial processes to control the surface dissipation of a material ported at high temperatures. To predict heat transfer and obtain the rate of required temperature distributions of the surface, it is necessary to understand the basic spray cooling dynamics and a more precise estimation of the heat transfer rate. This paper is about a three-dimensional simulation to estimate the transient heat transfer obtained locally by water spray to reduce the temperature of heated metal. The use of water spraying is a practical and flexible process. It is possible to vary, in space, time, and in large proportions the flux of extracted heat and controls the density of the flow of water which is a key element and very simple to achieve. Globally, the aim of this study is to simulate the spray cooling of different metal slabs for various alloys (steel, cast iron, titanium, nickel) by mainly comparing cooling in maps of iso-surfaces and in curves (at starts and globally) obtained after estimation of the heat flux.

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