A hydrodynamic model for subcooled liquid jet impingement at the Leidenfrost condition

Karwa, Nitin; Gambaryan‐Roisman, Tatiana; Stephan, Peter; Tropea, Cameron

doi:10.1016/j.ijthermalsci.2011.01.021

Cited by 43 publications

(24 citation statements)

References 13 publications

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“…3), which is corresponding to the minimum film boiling condition or the point of sharp rise in the temperature gradient, [5,[7][8][9]. The wetting delay, t d , is considered as the time taken by the surface to attaining the point (C), after the application of water jet onto the hot surface.…”

Section: Experimental Set Up and Proceduresmentioning

confidence: 99%

“…Whereas, in electronic industries jet of various fluids are being used to cool the high energy density electronic parts for improving their life and efficiency. Researchers have reported theoretical [3][4][5] and experimental [6][7][8][9] investigations several times in the literature for this cooling method. The performance of jet impingement surface cooling has been examined for both steady state [10][11][12][13] and transient [6][7][8][9][14][15][16][17][18][19][20][21] cooling conditions.…”

Section: Introductionmentioning

confidence: 99%

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Rewetting of hot vertical rod during jet impingement surface cooling

et al. 2015

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List of symbolsA Test-surface area (m 2 ) Bi Biot number, hD/2k s CHF Critical heat flux c p Specific heat of the surface material (kJ/kg K) d Jet diameter (m) D Test surface diameter (m) h Heat transfer coefficient (W/m 2 K) k Thermal conductivity (W/m K) l Downstream spatial location on test surface (m) Q Water flow rate (lpm) q Surface heat flux (W/m 2 ) Re Reynolds number (Ud/υ) Rw Rewetting number or dimensionless rewetting velocity (uD/2α) r Radial distance from the stagnation point (m) t Time (s) t d Wetting delay (s) T Temperature (°C) u Rewetting velocity (m/s) v Volume of test-section (m 3 ) z/d Dimensionless nozzle exit to test surface spacing Greek symbols υ Kinematic viscosity of water (m 2 /s) α Thermal diffusivity of surface (m 2 /s) ρ Density of surface material (kg/m 3 ) Subscripts B Bottom side downstream location e Experimental value i Initial value j Jet MFB Minimum film boiling m MaximumAbstract A stainless steel (SS-316) vertical rod of 12 mm diameter at 800 ± 10 °C initial temperature was cooled by normal impinging round water jet. The surface rewetting phenomenon was investigated for a range of jet diameter 2.5-4.8 mm and jet Reynolds number 5000-24,000 using a straight tube type nozzle. The investigation were made from the stagnation point to maximum 40 mm downstream locations, simultaneously for both upside and downside directions. The cooling performance of the vertical rod was evaluated on the basis of rewetting parameters i.e. rewetting temperature, wetting delay, rewetting velocity and the maximum surface heat flux. Two separate Correlations have been proposed for the dimensionless rewetting velocity in terms of rewetting number and the maximum surface heat flux that predicts the experimental data within an error band of ±20 and ±15 % respectively.

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Section: Experimental Set Up and Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rewetting of hot vertical rod during jet impingement surface cooling

et al. 2015

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“…Furthermore, if the total surface area to be cooled is much larger than the area of the jet, the cooling rate is found to be very low at a distance away from ' the stagnant point compared with that of the stagnant value [9,10]. When a large hot surface is being quenched by a high mass of smaller area jet, a tremendous vapor momentum is produced perpendicular to the surface due to which wall jets tend to separate from the surface and release the vapor produced [11,12]. This phenomenon is called Leidenfrost effect in which vapor film hinders the coolant to wet the hot surface thereby decreasing the heat dissipation rate.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Effect of Different Types of Surfactants and Jet Height on Cooling of a Hot Steel Plate

Ravikumar

Jha

Mohapatra

et al. 2014

Journal of Heat Transfer

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Heat transfer studies of a hot AISl 304 stainless steel plate by water jet impingement with different concentrations of three different types of surfactants have been investigated. The study involves a square plate of 100 mm x 100 mm surface area and 6 mm thickness with three subsurface thermocouples positioned at various locations inside the plate. The influence of jet height has been studied by varying the distance between the nozzle and plate from 200 mm to 600 mm. The results show that the heat transfer rate is found to increase with the jet height up to 400 mm and thereafter decreases due to capillaiy instability of liquid jet. Based on the maximum surface heat flux obtained for a particular nozzle height of 400 mm and an initial surface temperature of 900° C, further experiments have been carried out with different types of surfactants. The types of' surfactants used in the experimental study are anionic surfactant (sodium dodecyl sulphate, SDS), cationic surfactant (cetyltrimethylammonium bromide, CTAB) and nonionic surfactant (Polyoxyethylene 20 sorbitan monolaurate, Tween 20). During cooling, the transient temperature data measured by thermocouples have been analyzed by inverse heat conduction procedure to calculate surface heat flux and surface temperatures. The increase in surface heat flux has been observed with increasing concentration of surfactants and it has been found to be limited to a particular concentration of surfactant after which further increase in concentration leads to decrease in heat flux. Use of surfactant added water minimizes the surface tension and promotes better spreadability of coolant on the test specimen by reducing the solid-liquid contact angle. The maximum heat transfer rate has been found by using nonionic surfactant additive which can primarily be attributed to its lesser foam formability nature.

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“…Spray cooling with such a high cooling rates is called UFC [20 -22]. UFC can be defined as if the multiplication product of plate thickness (mm) and cooling rate (8C/s) is greater than a threshold value of 800, cooling is supposed to fall within UFC limits [23,24].…”

Section: Introductionmentioning

confidence: 99%

Study on Ultra-fast Cooling Behaviors of Water Spray Cooled Stainless Steel Plates

Aamir

Liu

Zhu

et al. 2015

Experimental Heat Transfer

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Spray cooling is an effective tool to dissipate high heat fluxes from hot surfaces. This article thoroughly investigates the effect of thickness of a hot stainless steel plate on the cooling time, cooling rate, heat flux, and heat transfer coefficient under constant mass flow rate maintained at 1 MPa using water as the coolant. Cylindrical samples of stainless steel with constant diameter (D 5 25 mm) and thickness (d 5 7.5, 12, 16.5, and 21 mm) were used in the present study. Critical droplet diameter to achieve an ultra-fast cooling rate of 3008C/s was estimated by using an analytical model for samples of varying thicknesses. The analytical model (one side spray cooling) showed good agreement with experimental results with a relative error of 3.2% in the plate thickness range of 1-12 mm. An increasing trend in maximum heat flux was found with increasing thickness of the plate. Maximum heat flux as high as 1,800 kW/m 2 was achieved for a 21-mm-thick sample. Heat transfer coefficients in the range 0.092-96.24 kW/m 2 K, 0.111-98.9 kW/m 2 K, 0.074-63.4 kW/m 2 K, and 0.127-55.63 kW/m 2 K were reported for sample of varying thicknesses in the present study. Limited published work is available with reference to water spray cooling dynamics and thickness of stainless steel plate. Therefore, the present study focuses on the correlation between the thickness of the plate and spray dynamics of water spray cooling.

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A hydrodynamic model for subcooled liquid jet impingement at the Leidenfrost condition

Cited by 43 publications

References 13 publications

Rewetting of hot vertical rod during jet impingement surface cooling

Rewetting of hot vertical rod during jet impingement surface cooling

Experimental Investigation of Effect of Different Types of Surfactants and Jet Height on Cooling of a Hot Steel Plate

Study on Ultra-fast Cooling Behaviors of Water Spray Cooled Stainless Steel Plates

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