An Investigation of the Effect of Inclination on Critical Heat Flux of PF-5060 Dielectric Liquid on Microporous Copper Surfaces

2013 ◽  
Author(s):  
Amir F. Ali ◽  
Mohamed S. El-Genk
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Inclination Angle ◽  
Pool Boiling ◽  
Dielectric Liquid ◽  
Copper Surfaces ◽  
Electrochemical Processes ◽  
Inclination Angles

Pool boiling experiments investigated the effect of inclination angle on the Critical Heat Flux (CHF) for saturation boiling of PF-5060 dielectric liquid on MicroPorous Copper (MPC) surfaces of different thicknesses (80 to 230 μm). The morphology of the surfaces, deposited using electrochemical processes, vary with the thickness, and hence CHF. The inclination angles investigated are 0° (upward facing), 60°, 90° (vertical), 120°, 150°, 160°, 170° and 180° (downward facing). CHF decreases with decreasing MPC thickness and/or increasing inclination angle. The CHF values in the upward facing orientation are 39%–67% higher than on smooth, polished Cu. For all MPC surfaces, CHF values in the downward facing orientation are ∼ 28% of those in the upward facing orientation (0°). The developed CHF correlation accounts for the effects of MPC thickness and inclination angle and is in agreement with experimental data to within ± 8%.

Saturation Boiling Critical Heat Flux of PF-5060 Dielectric Liquid on Microporous Copper Surfaces

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Mohamed S. El-Genk ◽  
Amir F. Ali
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Inclination Angle ◽  
Nucleate Boiling ◽  
Dielectric Liquid ◽  
Copper Surfaces ◽  
Inclination Angles ◽  
Surface Inclination ◽  
Effect Of Surface ◽  
Good Agreement

Pool boiling experiments are performed to investigate potential enhancement of critical heat flux (CHF) of PF-5060 dielectric liquid on microporous copper (MPC) surfaces and the effect of surface inclination angle. The morphology and microstructure of the MPC surfaces change with thickness. The experiments tested seven 10 × 10 mm MPC surfaces with thicknesses from 80 to 230 μm at inclination angles of 0 deg (upward facing), 60 deg, 90 deg (vertical), 120 deg, 150 deg, 160 deg, 170 deg, and 180 deg (downward facing). CHF increases as the thickness of the surface increases and/or the inclination angle decreases. The values in the upward facing orientation are 36–59% higher than on smooth Cu. For all surfaces, CHF values in the downward facing orientation are approximately 28% of those in the upward facing orientation. A developed CHF correlation, similar to those of Zuber and Kutateladze, accounts for the effects of inclination angle and thickness of the MPC surfaces. It is in good agreement with experimental data to within ±8%. Still photographs of nucleate boiling on the MPC surfaces at different inclinations help the interpretation of the experimental results.

Enhancement of critical heat flux (CHF) in pool boiling with anodized copper surfaces

2022 ◽  
Vol 172 ◽  
pp. 107338
Author(s):  
Atul Ranjan ◽  
Israr Ahmad ◽  
Rinku Kumar Gouda ◽  
Manabendra Pathak ◽  
Mohd Kaleem Khan
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Pool Boiling ◽  
Copper Surfaces

scholarly journals CHF of Pool Boiling on Microwires

2009 ◽  
Author(s):  
Jian-Fu Zhao ◽  
Yang-Hui Lu ◽  
Jing Li
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Pool Boiling ◽  
Bond Number ◽  
Working Fluids ◽  
Similar Range ◽  
Minimum Heat

The present paper reports a new series of experimental data of CHF (critical heat flux) of pool boiling on cylinders. Platinum wires of 30 mm in length are simultaneously used as heaters and thermometers. Their diameters are 0.1, 0.06, and 0.025 mm, respectively. FC-72 and acetone are used as working fluids. The range of the subcooling is from 0 K to about 50 K. The gaps between CHF and MHF (minimum heat flux) become narrower and narrower with the decrease of the heater diameter. But it exists even in the saturated pool boiling on the smallest wire in the present study. The dependence of CHF on the subcooling in acetone differs from that in FC-72 though the data locate in the similar range of Bond number in the two different kinds of working fluids. It indicates that interactions between the influences of the subcooling and size on CHF will be important for the small Bond number, and that there may exist some other parameters, which may be material-dependant, in addition to the Bond number that play important roles in the CHF phenomenon with small Bond number.

scholarly journals Method for calculating the critical heat flux at pool boiling on structured surfaces

2021 ◽  
Vol 2039 (1) ◽  
pp. 012034
Author(s):  
A V Stupakova ◽  
A V Dedov
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Pool Boiling ◽  
Calculated Data ◽  
Porous Space ◽  
Structured Surfaces ◽  
Evaporation Zone ◽  
Microstructured Surfaces ◽  
Irregular Geometries

Abstract A method of the critical heat flux enhancements at pool boiling using rough structures of various regular and irregular geometries is investigated. The experimental data are compared, and the critical heat flux is calculated since the V. V. Yagov model, which considers the additional inflow of liquid into the evaporation zone due to the action of capillary forces in the porous space. Based on the comparison of experimental and calculated data, it is concluded that the model is not universal for all microstructured surfaces. Recommendations for the calculation are given.

Subcooled Pool Boiling Critical Heat Flux in Dielectric Liquid Mixtures

1993 ◽  
Vol 115 (1) ◽  
pp. 134-137 ◽  
Author(s):  
T. Y. Tom Lee ◽  
Mali Mahalingam ◽  
Peter J. C. Normington
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Pool Boiling ◽  
Liquid Mixtures ◽  
Dielectric Liquid ◽  
Electronic Data Collection ◽  
Dielectric Liquids ◽  
Boiling Points ◽  
The Family ◽  
Perfluorocarbon Liquids

The beneficial effect of using dielectric liquid mixture in reducing temperature overshoot in pool boiling has been studied by the authors (Normington et al., 1992). The current experimental work addresses the influence of mixtures of dielectric liquids on the critical heat flux (CHF) in pool boiling. Two families of dielectric liquids were evaluated: perfluorocarbon liquids and perfluoropolyether liquids. Each set of the family consisted of two liquids with boiling points ranging from 80°C−110°C. Both 100 percent of each liquid and mixtures of two liquids were tested. Video filming was used along with electronic data collection. The perfluoropolyether liquids showed an increase in CHF as more high boiling liquid was added to the mixture, while the perfluorocarbon liquids had a constant CHF for all mixtures.

Study on Ex-Vessel Cooling of RPV: Model Analysis of Critical Heat Flux on Inclined Plate Facing Downward and Development to Hemispherical Surface

2002 ◽  
Author(s):  
Hiroyasu Ohtake ◽  
Yasuo Koizumi
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Inclination Angle ◽  
Present Model ◽  
Finite Thickness ◽  
Vapor Flow ◽  
Helmholtz Instability ◽  
Saturated Boiling ◽  
Inclined Plates

The cooling of the Ex-vessel in Light-Water-Reactors has been proposed to maintain reactor vessel integrity during severe accident. The critical heat flux — CHF — from the underside of down-facing convex surfaces, like hemispheres, is important to the assessment of the cooling. The authors examined CHFs on inclined plates under saturated boiling experimentally, focusing on the effect of the inclination angle on the CHF and characteristic length and velocity of coalesced bubbles near the heater at the CHF. In this study, the critical heat fluxes on the inclined plates in saturated boiling were investigated analytically by using the macrolayer model and the Kelvin-Helmholtz instability, based on our previous experimental report. Furthermore, the present model was developed for the CHF on a hemispheric surface. In the present model, the most dangerous wavelength and propagative velocity of the wave in the Kelvin-Helmholtz instability for ideal fluid with vapor flow of finite thickness and surface tension on liquid-vapor interface were calculated to determine the length and the velocity of the coalesced bubble on the heating surface at CHF. The time covered over the heater with the bubble was estimated as the calculated value with the length divided by the velocity. The predictions of the present CHF model by using the macrolayer model for CHF and the Kelvin-Helmholtz instability for the characteristic values of the coalesced bubble agree well with previous experimental data for CHF on inclined plates with 30 to 180 degree in orientation. Furthermore, the present model given as a function of the inclination angle relative to the horizontal downward plate was extended to CHF on a hemispheric surface. The CHFs obtained by the present model are in qualitative agreement with experimental data on hemispheres reported by some investigators.

A Systematic Approach to Predicting Critical Heat Flux for Inclined Sprays

2007 ◽  
Vol 129 (4) ◽  
pp. 452-459 ◽  
Author(s):  
Milan Visaria ◽  
Issam Mudawar
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Inclination Angle ◽  
High Speed ◽  
Systematic Approach ◽  
Test Surface ◽  
Great Success ◽  
Spray Formation ◽  
Inclination Angles ◽  
The Impact

This study provides a new systematic approach to predicting the effects of spray inclination on critical heat flux (CHF). Experiments were performed with three pressure spray nozzles over a broad range of inclination angles at five flow rates and subcoolings of 15°C and 25°C. These experiments also included high-speed video analysis of spray formation, impact, and recoil for a 1.0×1.0cm2 test surface. Inclined sprays produced elliptical impact areas, distorted by lateral liquid flow that provided partial resistance to dryout along the downstream edge of the impact ellipse. These observations are used to determine the locations of CHF commencement along the test surface. A new theoretical model shows that increasing inclination angle away from normal decreases both the spray impact area and the volumetric flux. These trends explain the observed trend of decreasing CHF with increasing inclination angle. Combining the new model with a previous point-based CHF correlation shows great success in predicting the effects of spray inclination on CHF.

INVESTIGATING THE RELATIONSHIP BETWEEN SURFACE WICKABILITY AND CRITICAL HEAT FLUX DURING POOL BOILING

2018 ◽  
Author(s):  
Youngsup Song ◽  
Yangying Zhu ◽  
Daniel J. Preston ◽  
H. Jeremy Cho ◽  
Zhengmao Lu ◽  
...  
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Pool Boiling ◽  
The Relationship

THE CRITICAL HEAT FLUX AT THE POOL BOILING OF SOME BINARY LIQUID MIXTURES

2019 ◽  
Author(s):  
Samson Semenovich Kutateladze ◽  
G.I. Bobrovich ◽  
I. I. Gogonin ◽  
N.N. Mamontova ◽  
V.N. Moskvicheva
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Pool Boiling ◽  
Liquid Mixtures ◽  
Binary Liquid Mixtures ◽  
Binary Liquid
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