scholarly journals Pool Boiling Curve in Microgravity

1997 ◽  
Vol 11 (2) ◽  
pp. 216-222 ◽  
Author(s):  
Ho Sung Lee ◽  
Herman Merte ◽  
Francis Chiaramonte
Keyword(s):  
Pool Boiling ◽  
Boiling Curve

Observations of the Critical Heat Flux Process During Pool Boiling of FC-72

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
J. Jung ◽  
S. J. Kim ◽  
J. Kim
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Pool Boiling ◽  
High Heat ◽  
Line Length ◽  
Boiling Curve ◽  
High Heat Flux ◽  
Transfer Coefficients ◽  
Ir Camera

Experimental work was undertaken to investigate the process by which pool-boiling critical heat flux (CHF) occurs using an IR camera to measure the local temperature and heat transfer coefficients on a heated silicon surface. The wetted area fraction (WF), the contact line length density (CLD), the frequency between dryout events, the lifetime of the dry patches, the speed of the advancing and receding contact lines, the dry patch size distribution on the surface, and the heat transfer from the liquid-covered areas were measured throughout the boiling curve. Quantitative analysis of this data at high heat flux and transition through CHF revealed that the boiling curve can simply be obtained by weighting the heat flux from the liquid-covered areas by WF. CHF mechanisms proposed in the literature were evaluated against the observations.

An Experimental Study of Miniature-Scale Pool Boiling

2003 ◽  
Vol 125 (6) ◽  
pp. 1074-1086 ◽  
Author(s):  
Tailian Chen ◽  
Jacob N. Chung
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Boiling Curve ◽  
Feedback Control System ◽  
Electronic Feedback ◽  
Fundamental Understanding ◽  
Peak Heat Flux ◽  
Different Temperatures

By generating single bubbles on a micro-heater at different wall superheats, an experimental study of miniature-scale pool boiling heat transfer has been performed to provide a fundamental understanding of the heater size effect. In this study, the constant-temperature microheater is set at different temperatures by an electronic feedback control system. The heat transfer history during the lifetime of a single bubble which includes nucleation, growth, detachment and departure has been measured. The boiling curve obtained from the microheater is composed of two regimes which are separated by a peak heat flux. It is suggested that in the lower superheat regime, the boiling is dominated by liquid rewetting and micro-layer evaporation, while in the higher superheat regime, conduction through the vapor film and micro-convection plays the key heat transfer role as the heater is covered by vapor all the time. In general, boiling on microheaters is characterized by larger bubble departure sizes, smaller bubble growth rates due to the dryout of microlayer as the bubble grows, and higher bubble incipience superheat. As the heater size decreases, the boiling curve shifts towards higher heat fluxes with corresponding higher superheats.

Transient Characteristics of Pool Boiling Heat Transfer in Nanofluids

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Sang M. Kwark ◽  
Ratan Kumar ◽  
Gilberto Moreno ◽  
Seung M. You
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Base Fluid ◽  
Pool Boiling ◽  
Thermal Characteristics ◽  
Boiling Curve ◽  
Heater Surface ◽  
Cooling Fluid ◽  
Transient Characteristics ◽  
Conductivity Enhancement

This study shows the transient characteristics of the pool boiling curves using nanofluid as the boiling fluid. This time-dependency is in sharp contrast to a unique steady-state pool boiling curve that is typically obtained for a pure fluid. Past nanofluids research has provided interesting information about the thermal characteristics for this potentially promising cooling fluid. Results from these studies have shown some extraordinary critical heat flux (CHF) values and thermal conductivity enhancement that is yet to be explained by existing theories and correlations. The nature of the pool boiling curve for a nanofluid is dependent on the nanoparticle concentration in the base fluid. Higher concentration nanofluids show a perceptible degradation in the boiling heat transfer (BHT) coefficient but have exhibited an enhanced CHF value (up to ∼80%) when compared to the CHF value of the base fluid (water). Another key observation has been in the significant deposition of nanoparticles on the heater surface. This fouling of the heater surface by nanoparticles is widely viewed as a main contributor that modifies the pool boiling curve of the base liquid. The deposition of the nanoparticles on the heater surface is dynamic and this in turn makes the nanofluid pool boiling curve exhibit transient characteristics.

Characteristics of Nucleate Pool Boiling From Porous Metallic Coatings

1982 ◽  
Vol 104 (2) ◽  
pp. 279-285 ◽  
Author(s):  
A. E. Bergles ◽  
M. C. Chyu
Keyword(s):  
Pilot Plant ◽  
Tube Bundle ◽  
Pool Boiling ◽  
Metallic Matrix ◽  
Boiling Curve ◽  
Nucleate Pool Boiling ◽  
Metallic Coatings ◽  
Single Tube ◽  
Matrix Surface

A study of pool boiling from a commercial porous metallic matrix surface is reported. The excellent steady boiling characteristics of this type of surface are confirmed; however, high wall superheats are required in most cases to initiate boiling. The resultant boiling curve hysteresis does not appear to have been previously reported in the literature. This effect is indicated in recent pilot plant tests. The present results generally confirm the speculated mechanism of boiling with these surfaces and suggest reasons whereby single-tube performance may be superior to tube bundle performance.

An experimental investigation on the entire pool boiling curve of R14 under 0.1 MPa pressure

2014 ◽  
Vol 41 ◽  
pp. 164-170 ◽  
Author(s):  
Ch. Zhao ◽  
M.Q. Gong ◽  
L. Ding ◽  
X. Zou ◽  
G.F. Chen ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Pool Boiling ◽  
Boiling Curve

Transient Characteristics of Pool Boiling Heat Transfer in Nanofluids

2009 ◽  
Author(s):  
Sang M. Kwark ◽  
Ratan Kumar ◽  
Gilberto Moreno ◽  
Seung M. You
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Base Fluid ◽  
Pool Boiling ◽  
Thermal Characteristics ◽  
Boiling Curve ◽  
Heater Surface ◽  
Transient Characteristics ◽  
Conductivity Enhancement ◽  
Boiling Heat Transfer Coefficient

This study shows the transient characteristics of the pool boiling curves using nanofluid as the boiling fluid. This time-dependency is in sharp contrast to a unique steady-state pool boiling curve that is typically obtained for a pure fluid. Past researches on nanofluids have provided several interesting information about the thermal characteristics for this potentially promising cooling fluid. Results from these studies have shown some extraordinary critical heat flux (CHF) values and thermal conductivity enhancement that is yet to be explained by existing theories and correlations. The nature of the pool boiling curve for a nanofluid is dependent on the nanoparticle concentration in the base fluid. Higher concentration nanofluids show a perceptible degradation in the boiling heat transfer coefficient but have exhibited an enhanced CHF value (up to ∼80%) when compared to the CHF value of the base fluid (water). Another key observation has been in the significant deposition of nanoparticles on the heater surface. This fouling of the heater surface by nanoparticles is widely viewed as a main contributor that modifies the pool boiling curve of the base liquid. The deposition of the nanoparticles on the heater surface is dynamic and this in turn makes the nanofluid pool boiling curve exhibit transient characteristics.

A Unified Three Dimensional Numerical Simulation of the Pool Boiling Curve

2017 ◽  
Author(s):  
Deepak Garg ◽  
Vijay K. Dhir
Keyword(s):  
Heat Flux ◽  
Contact Angle ◽  
Numerical Model ◽  
Critical Heat Flux ◽  
Void Fraction ◽  
Pool Boiling ◽  
Three Dimensional ◽  
Boiling Curve ◽  
Wall Superheat ◽  
Experimental Values

Three dimensional numerical simulations for pool boiling of saturated water at atmospheric pressure conditions are performed on a horizontal surface using finite difference method under the framework of parallel computing. Since heat conduction in the solid phase is not considered, in order to simulate realistic heating surface, dependence of bubble nucleation frequency and nucleation site density on wall superheat and contact angle are obtained from the correlations reported in the literature. Steady state boiling curve for all the three regimes viz. nucleate, transition and film boiling has been obtained with a unified numerical model by incrementing the wall superheat for a static contact angle of 38°. Evaporative heat flux from the microlayer is separately accounted for in the present study by sub grid modeling. Both the phases are considered as incompressible while the interface separating the phases is solved using level set method. The governing equations of mass, momentum and energy for both the liquid and the vapor phase are solved coupled with the jump conditions at the interface employing ghost fluid and cut cell method. Diffusion terms are treated implicitly while convection terms are treated using second order ENO scheme. Spatial and temporal averaged wall heat flux and wall void fraction are plotted and compared against correlations and experimental values previously reported. The nucleate boiling heat flux obtained from the present numerical model is under predicted in comparison to the Stephan and Abdelsalam correlation. Comparison of the computed wall void fraction against experimental values is done for the transition boiling region. At critical heat flux formation of long vapor column was seen while intermittent liquid surface contacts were seen in the transition boiling regime. The computed critical heat flux value is lower than that obtained from the correlation of Maracy and Winterton.

scholarly journals Effects of Surface Conditions on Nucleate Pool Boiling of Sodium

1966 ◽  
Vol 88 (2) ◽  
pp. 196-203 ◽  
Author(s):  
P. J. Marto ◽  
W. M. Rohsenow
Keyword(s):  
Pool Boiling ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Boiling Curve ◽  
Porous Coatings ◽  
Surface Conditions ◽  
Effect Of Pressure ◽  
Pool Depth ◽  
Commercial Grade ◽  
Surface Finishes

Commercial grade sodium was boiled from a horizontal disk at pressures of 65 mm, 200 mm, and 400 mm Hg absolute, with sodium temperatures ranging from 1200 F to 1500 deg F. Heat fluxes as high as 236,000 Btu/hr sq ft were attained. Boiler surface finishes ranged from highly polished mirror finishes to coarse, porous coatings. By following a prescribed cleaning and filling procedure, nucleate-boiling results were generally reproducible for a given-type surface. The effect of roughness as well as any aging and hysteresis effects were experimentally determined. Incipient nucleate boiling results are discussed as well as the effect of pressure and pool depth on the nucleate-boiling curve.

scholarly journals Numerical Investigation of Pool Boiling Under Ocean Condition with Lattice Boltzmann Simulation. Part Ⅱ: Rolling Condition

2021 ◽  
Vol 9 ◽  
Author(s):  
Qifan Zou ◽  
Xiuliang Liu ◽  
Yongyan Hu ◽  
Yuxuan Chang ◽  
Pengkun Li
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Lattice Boltzmann ◽  
Pool Boiling ◽  
Inertial Force ◽  
Boiling Curve ◽  
Rolling Motion ◽  
Inertial Forces ◽  
Rolling Condition ◽  
Transient Heat Flux

Rolling motion caused by ocean condition will induce more complicated inertial forces with their force directions changing all the time, which results more complex bubble behaviors and unique heat transfer characteristics. In this work, pool boiling under rolling condition is numerically simulated using multiple relaxation time phase change lattice Boltzmann method (LBM). Pool boiling patterns, boiling curve of time-averaged heat flux, transient heat flux and rolling effects on different pool boiling regions are investigated. The results show that pool boiling curve of time-averaged heat flux between rolling condition and static condition are not obvious until close to critical heat flux, and 9.3% higher CHF is achieved under rolling condition while worse heat transfer is discovered at film boiling. Moreover, distinct fluctuation of transient heat flux of pool boiling under rolling condition is found for all boiling regimes, and its variation pattern along with the rolling motion and bubble behavior is investigated. Furthermore, tangential inertial force caused by rolling motion has positive influence on heat transfer of pool boiling, while the centrifugal force has negative influence on heat transfer, since it is opposite to the gravity and hence decreases the buoyancy force. Besides, larger rolling amplitude and smaller rolling period will induce larger additional inertial forces, and thus make greater influences on the bubbles’ behavior and pool boiling heat transfer.

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