A Correlation for Critical Heat Flux in Submerged Jet Impingement

2012 ◽  
Author(s):  
Ruander Cardenas ◽  
Vinod Narayanan
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Jet Impingement ◽  
Maximum Error ◽  
Nozzle Diameter ◽  
Average Error ◽  
Submerged Jet ◽  
System Pressure ◽  
Wide Range ◽  
Jet Impingement Boiling

Data from an extensive experimental study of submerged jet impingement boiling performed with water at sub-atmospheric pressures and with FC-72 at atmospheric pressure are used to develop a predictive critical heat flux (CHF) correlation for use in thermal management of electronic components. The configuration was that of a circular submerged jet impinging on a high-thermal-capacity copper surface with a standoff distance of 6 nozzle diameters. Varied parameters included the Reynolds numbers (Re) from 0 (pool boiling) to 14000, surface-to-nozzle diameter ratios (by varying the nozzle diameter) from 25 to 6, system pressures (0.2, 0.3, 0.5, 1 bar), surface roughness (123 nm, 33 nm), and system subcooling. CHF is found to increase with Re, system pressure, subcooling, and roughness and decreases with increase in nozzle diameter for a fixed Re. Comparison with correlations in literature indicated that data of sub-atmospheric jet impingement of water were poorly predicted by existing correlations while the Monde and Katto correlation [1] was found to predict the atmospheric jet impingement data with FC-72 within 10 percent at Re >4000. Data from the experiments were fitted to a submerged forced convective CHF model proposed by Haramura and Katto [2] to develop a correlation for submerged jet impingement boiling over a wide range of density ratios. Using this model, the entire CHF dataset from experiments can be predicted with a maximum error of less than 11 percent and an average error of less than 2.6 percent.

Critical Heat Flux in Submerged Jet Impingement Boiling of Water Under Subatmospheric Conditions

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Ruander Cardenas ◽  
Vinod Narayanan
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Jet Impingement ◽  
Maximum Error ◽  
Average Error ◽  
Experimental Conditions ◽  
Data Set ◽  
Submerged Jet ◽  
Fluid Saturation ◽  
Jet Impingement Boiling

Critical heat flux (CHF) characteristics in submerged jet impingement boiling of water on a heated copper surface are investigated at subatmospheric conditions. Data are reported at a fixed surface-to-nozzle diameter ratio of 23.8 and a fixed surface-to-nozzle height of 6 nozzle diameters. Three subatmospheric pressures of 0.176 bars, 0.276 bars, and 0.477 bars are considered, corresponding to fluid saturation temperatures of 57.3 °C, 67.2 °C, and 80.2 °C and liquid-to-vapor density ratios of 8502, 5544, and 3295, respectively. At each pressure, CHF for varying jet Reynolds numbers (Re) in the range 0–14,000 are compared for two different surface finishes of roughness average values of 123 nm and 33 nm. The CHF enhancement observed with increasing Re is depicted in a nondimensional CHF map. Existing correlations available in the literature, which are out of range of the current experimental conditions, are found to poorly predict the obtained CHF data. A CHF correlation that captures the entire experimental data set within an average error of ±3% and a maximum error of ±13% is developed. The effect of fluid subcooling on submerged jet CHF is studied at the lowest pressure of 0.176 bars. Subcooled jet CHF is found to be well predicted from saturated jet CHF by using a typical subcooled pool boiling CHF correction factor.

Critical Heat Flux During Submerged Jet Impingement Boiling of Saturated Water at Sub-Atmospheric Conditions

2011 ◽  
Author(s):  
Ruander Cardenas ◽  
Vinod Narayanan
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Jet Impingement ◽  
Atmospheric Conditions ◽  
Predictive Tool ◽  
Submerged Jet ◽  
Fluid Saturation ◽  
Saturated Water ◽  
Jet Impingement Boiling

Experimental data for critical heat flux (CHF) during submerged jet impingement boiling of saturated water at sub-atmospheric conditions is presented. Experiments are performed at three sub-atmospheric pressures of 0.176 bar, 0.276 bar, and 0.477 bar with corresponding fluid saturation temperatures of about 57.3 °C, 67.2 °C, and 80.2 °C. Jet exit Reynolds numbers ranging from 0 to 14,000 are considered for two different heater surface finishes at a fixed nozzle to surface spacing of six nozzle diameters. CHF correlations from literature on jet impingement boiling are compared against the experimental data and found to poorly predict CHF under the conditions considered. A CHF correlation that captures the entire experimental data set within an average error of ±3 percent and a maximum error of ±13 percent is developed to serve as a predictive tool for the range of conditions examined.

Submerged Jet Impingement Boiling on a Polished Silicon Surface

2011 ◽  
Author(s):  
Preeti Mani ◽  
Ruander Cardenas ◽  
Vinod Narayanan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Silicon Surface ◽  
High Speed ◽  
Jet Impingement ◽  
Working Fluid ◽  
Uniform Heat Flux ◽  
Submerged Jet ◽  
Jet Impingement Boiling

Submerged jet impingement boiling has the potential to enhance pool boiling heat transfer rates. In most practical situations, the surface could consist of multiple heat sources that dissipate heat at different rates resulting in a surface heat flux that is non-uniform. This paper discusses the effect of submerged jet impingement on the wall temperature characteristics and heat transfer for a non-uniform heat flux. A mini-jet is caused to impinge on a polished silicon surface from a nozzle having an inner diameter of 1.16 mm. A 25.4 mm diameter thin-film circular serpentine heater, deposited on the bottom of the silicon wafer, is used to heat the surface. Deionized degassed water is used as the working fluid and the jet and pool are subcooled by 20°C. Voltage drop between sensors leads drawn from the serpentine heater are used to identify boiling events. Heater surface temperatures are determined using infrared thermography. High-speed movies of the boiling front are recorded and used to interpret the surface temperature contours. Local heat transfer coefficients indicate significant enhancement upto radial locations of 2.6 jet diameters for a Reynolds number of 2580 and upto 6 jet diameters for a Reynolds number of 5161.

Critical Heat Flux in Tubes With Cosine Axial Heat Flux

2005 ◽  
Author(s):  
W. Jaewoo Shim ◽  
Joo-Yong Park ◽  
Ji-Su Lee ◽  
Dong Kook Kim
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Mass Flux ◽  
Flux Distribution ◽  
Average Error ◽  
Uniform Heat Flux ◽  
Heat Flux Distribution ◽  
Uniform Heat ◽  
System Pressure ◽  
Data Points

In this study a method to predict CHF (Critical Heat Flux) in vertical round tubes with cosine heat flux distribution was examined. For this purpose a uniform correlation, based on local condition hypothesis, was developed from 9,366 CHF data points of uniform heat flux heaters. The CHF data points used were collected from 13 different sources had the following parameter ranges: 1.01 ≤ P (pressure) ≤ 206.79 bar, 9.92 ≤ G (mass flux) ≤ 18,619.39 kg/m2s, 0.00102 ≤ D (diameter) ≤ 0.04468 m, 0.0254 ≤ L (length) ≤ 4.966 m, 0.11 ≤ qc (CHF) ≤ 21.42 MW/m2, and −0.87 ≤ X (exit qualities) ≤ 1.58. The result of this work showed that the uniform CHF correlation could be used to predict CHF accurately in a non-uniform heat flux heater for wide flow conditions. Furthermore, the location, where CHF occurs in non-uniform heat flux distribution, can also be determined accurately with the local variables: the system pressure (P), tube diameter (D), mass flux of water (G), and true mass flux of vapor (GXt). The new correlation predicted CHF with cosine heat flux, 297 data points from 5 different published sources, within the root mean square error of 12.42% and average error of 1.06% using the heat balance method.

Sub-Atmospheric Mini-Jet Impingement Boiling of Water Under Saturated and Subcooled Conditions

2011 ◽  
Author(s):  
Ruander Cardenas ◽  
Preeti Mani ◽  
Vinod Narayanan
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Pool Boiling ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Internal Diameter ◽  
Atmospheric Conditions ◽  
Surface Distance ◽  
Jet Impingement Boiling ◽  
Effect Of Surface

An experimental study of mini-jet impingement boiling is presented for saturated and subcooled conditions. Unique to this study is the documentation of boiling curves of submerged water jet impingement under sub-atmospheric conditions. Data are reported at a single sub-atmospheric pool pressure of 0.176 bar and for a fixed nozzle-to-surface distance of six jet diameters. A mini nozzle is used in the present study with an internal diameter of 1.16 mm. Jet impingement boiling at Reynolds numbers in the range of 0 to 6,800 are characterized and contrasted for both saturated and subcooled conditions. Enhancements in critical heat flux with increasing Re are observed for both saturated and subcooled conditions, with the subcooled condition of 17 °C showing approximately 2.3 times the critical heat flux as that observed for saturated conditions. Critical heat flux for subcooled jet impingement boiling is well predicted from the saturated critical heat flux data by a modified subcooled pool boiling CHF correlation presented by Inoue et al. [1]. The effect of surface finish on pool boiling is also reported.

Confined Submerged Jet Impingement Boiling of Subcooled FC-72 over Micro-Pin-Finned Surfaces

2015 ◽  
Vol 37 (3-4) ◽  
pp. 269-278 ◽  
Author(s):  
Yonghai Zhang ◽  
Jinjia Wei ◽  
Xin Kong ◽  
Ling Guo
Keyword(s):  
Jet Impingement ◽  
Submerged Jet ◽  
Jet Impingement Boiling

Single-Phase and Boiling Cooling of Small Pin Fin Arrays by Multiple Nozzle Jet Impingement

1996 ◽  
Vol 118 (1) ◽  
pp. 21-26 ◽  
Author(s):  
David Copeland
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Single Phase ◽  
Jet Impingement ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Heat Transfer Coefficients ◽  
Aspect Ratios ◽  
Pin Fin Arrays

Experimental measurements of multiple nozzle submerged jet array impingement single-phase and boiling heat transfer were made using FC-72 and 1 cm square copper pin fin arrays, having equal width and spacing of 0.1 and 0.2 mm, with aspect ratios from 1 to 5. Arrays of 25 and 100 nozzles were used, with diameters of 0.25 to 1.0 mm providing nozzle area from 5 to 20 mm2 (5 to 20% of the heat source base area). Flow rates of 2.5 to 10 cm3/s (0.15 to 0.6 l/min) were studied, with nozzle velocities from 0.125 to 2 m/s. Single nozzles and smooth surfaces were also evaluated for comparison. Single-phase heat transfer coefficients (based on planform area) from 2.4 to 49.3 kW/m2 K were measured, while critical heat flux varied from 45 to 395 W/cm2. Correlations of the single-phase heat transfer coefficient and critical heat flux as functions of pin fin dimensions, number of nozzles, nozzle area and liquid flow rate are provided.

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