scholarly journals Survey on the nucleate pool boiling of hydrogen and its limits

2020 ◽  
Vol 4 (2) ◽  
pp. 157-166
Author(s):  
Touhami Baki
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Low Temperature ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Temperature Gradients ◽  
Nucleate Pool Boiling ◽  
Reduced Pressure ◽  
Predicted Values ◽  
Efficient Transfer

Nucleate pool boiling is a very efficient transfer regime with low temperature gradients, bounded between two heat flux values and which border transitions to other regimes, this phenomenon is well framed with correlations; our study aims to clarify the applicability of this regime to liquid hydrogen and to develop reliable correlations for a useful and qualitative agreement. An exhaustive review on the nucleate pool boiling of hydrogen and the limits of this regime, whether are the onset nucleate boiling (ONB) and the critical heat flux (CHF) was made, allowing the collection of more than 1400 points from experimental setups, highlighting a variety of parameters. Five predictive correlations were drawn from the literature, graphical and statistical comparisons were made, two in five reveal acceptable results. After analysis of the experimental data, new correlations were developed and compared with the data collected, convincing results were obtained and discussed. A simple form was expressed for the heat flux , shows better predicted values; convincing results of the (CHF) have been found on modified Kutateladze correlation (1948), and the CHF value reaches a maximum of 148×103 W/m² for a reduced pressure at 0.35; a nucleate boiling correlation suitable for hydrogen has been developed.

Investigation of the Dynamics of Nucleate Boiling in Subcooled Falling Liquid Films

2014 ◽  
Vol 9 (2) ◽  
pp. 145-155
Author(s):  
Vladimir Serdyukov ◽  
Anton Surtaev ◽  
Oleg Volodin
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Strong Dependence ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Liquid Films ◽  
Heat Fluxes ◽  
Nucleation Frequency ◽  
Water Films ◽  
Falling Liquid Films

This paper deals with the features of nucleation dynamics at boiling in falling water films at different subcooling, Reynolds number and heat fluxes. With the use of high-speed infrared and digital video the local parameters of nucleate boiling in falling liquid films such as: bubbles’ diameter before condensation, frequency of nucleation and temperature of onset of bubble appearance were received. Analysis of the experimental data showed that bubbles’ diameter before condensation has strong dependence on initial temperature and increases with the rise of heat flux. The main influence on nucleation frequency has the variation of heat flux density. At the same time the experimental data on nucleation frequency in falling water films are close to the frequency of nucleation at pool boiling. To identify the main features the comparison of received data on the local characteristics at boiling in subcooled falling liquid film with existing models for pool boiling was made

Bubble Dynamics for Nucleate Pool Boiling of Electrolyte Solutions

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Seyed Ali Alavi Fazel ◽  
Seyed Baher Shafaee
Keyword(s):  
Experimental Data ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Close Relation ◽  
Electrolyte Solutions ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Nucleate Pool Boiling ◽  
Wide Range

Bubble dynamics is the most important subphenomenon, which basically affects the nucleate pool boiling heat transfer coefficient. Previous investigations state that the effect of physical properties of liquid and vapor phases on bubble departure diameter are often conflicting. In this article, extensive new experimental data are presented for the bubble departure diameter for various electrolyte aqueous solutions over a wide range of heat fluxes and concentrations. Experimental results show that the bubble detachment diameter increase with increasing either boiling heat flux or electrolyte concentration. Experimental results also present a close relation between the dimensionless capillary and bond numbers. A new model for the prediction of vapor bubble departure diameter in nucleate boiling for the electrolyte solutions is proposed, which predicts the experimental data with a satisfactory accuracy.

scholarly journals Predicting Conduction Heat Flux through Macrolayer in Nucleate Pool Boiling

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3893
Author(s):  
Mohd Danish ◽  
Mohammed K. Al Mesfer ◽  
Khursheed B. Ansari ◽  
Mudassir Hasan ◽  
Abdelfattah Amari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Current Model ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
High Heat ◽  
High Heat Flux ◽  
Nucleate Pool Boiling ◽  
Conduction Heat Transfer ◽  
Wall Superheat

In the current work, the heat flux in nucleate pool boiling has been predicted using the macrolayer and latent heat evaporation model. The wall superheat (ΔT) and macrolayer thickness (δ) are the parameters considered for predicting the heat flux. The influence of operating parameters on instantaneous conduction heat flux and average heat flux across the macrolayer are investigated. A comparison of the findings of current model with Bhat’s decreasing macrolayer model revealed a close agreement under the nucleate pool boiling condition at high heat flux. It is suggested that conduction heat transfer strongly rely on macrolayer thickness and wall superheat. The wall superheat and macrolayer thickness is found to significantly contribute to conduction heat transfer. The predicted results closely agree with the findings of Bhat’s decreasing macrolayer model for higher values of wall superheat signifying the nucleate boiling. The predicted results of the proposed model and Bhat’s existing model are validated by the experimental data. The findings also endorse the claim that predominant mode of heat transfer from heater surface to boiling liquid is the conduction across the macrolayer at the significantly high heat flux region of nucleate boiling.

Nucleate boiling heat transfer coefficients of halogenated refrigerants up to critical heat fluxes

2009 ◽  
Vol 223 (6) ◽  
pp. 1415-1424 ◽  
Author(s):  
K-J Park ◽  
D Jung ◽  
S E Shim
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Nucleate Pool Boiling ◽  
Transfer Coefficients ◽  
Average Deviation ◽  
Heat Transfer Coefficients

In this work, nucleate pool boiling heat transfer coefficients (HTCs) of five refrigerants of differing vapour pressures are measured on a horizontal, smooth copper surface of 9.53×9.53 mm. The tested refrigerants are R123, R152a, R134a, R22, and R32 and HTCs are taken from 10 kW/m2 to the critical heat flux (CHF) of each refrigerant. Wall and fluid temperatures are measured directly by thermocouples located underneath the test surface and in the liquid pool, respectively. Test results show that nucleate pool boiling HTCs of halogenated refrigerants increase as the heat flux and vapour pressure increase. This typical trend is maintained even at high heat fluxes above 200 kW/m2. Zuber's prediction equation for CHF is quite accurate showing a maximum deviation of 21 per cent for all refrigerants tested. For all refrigerants, Stephan and Abdelsalam's well-known correlation underpredicted nucleate boiling HTC data up to the CHF with an average deviation of 21.3 per cent, while Cooper's correlation overpredicted the data with an average deviation of 14.2 per cent. On the other hand, Gorenflo's and Jung et al.'s correlations showed 5.8 and 6.4 per cent deviations, respectively, in the entire nucleate boiling range up to the CHF.

scholarly journals Developing a Mathematical Model for Nucleate Boiling Regime at High Heat Flux

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 726
Author(s):  
Mohd Danish ◽  
Mohammed Al Mesfer
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Close Agreement ◽  
Current Model ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
High Heat ◽  
High Heat Flux ◽  
Nucleate Pool Boiling ◽  
Wall Superheat

A mathematical model has been developed for heat exchange in nucleate boiling at high flux applying an energy balance on a macrolayer. The wall superheat, macrolayer thickness, and time are the parameters considered for predicting the heat flux. The influence of the wall superheat and macrolayer thickness on average heat flux has been predicted. The outcomes of the current model have been compared with Bhat’s constant macrolayer model, and it was found that these models are in close agreement corresponding to the nucleate pool boiling regime. It was concluded that the wall superheat and macrolayer thickness contributed significantly to conduction heat transfer. The average conduction heat fluxes predicted by the current model and by Bhat’s model are in close agreement for a thinner macrolayer of approximately 50 µm. For higher values of the wall superheat, which corresponds to the nucleate pool boiling condition, the predicted results strongly agree with the results of Bhat’s model. The findings also validate the claim that conduction across the macrolayer accounts for the main heat transfer mode from the heater surface to boiling liquid at high heat flux in nucleate pool boiling.

On Correlating the Peak and Minimum Boiling Heat Fluxes With Pressure and Heater Configuration

1966 ◽  
Vol 88 (1) ◽  
pp. 94-99 ◽  
Author(s):  
John H. Lienhard ◽  
Kiyokazu Watanabe
Keyword(s):  
Heat Flux ◽  
Pressure Range ◽  
Pool Boiling ◽  
Three Dimensional ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Reduced Pressure ◽  
Minimum Heat ◽  
Dimensional Surface ◽  
Horizontal Wire

The peak nucleate boiling heat flux has been observed for five fluids during saturated pool boiling on horizontal wire heaters, ranging in radius from 0.0025 in. to 0.0254 in., over a reduced pressure range from 0.0010 to 0.0197. A scheme for correlating the peak and minimum heat fluxes is developed heuristically and successfully applied to these data. The result is a single three-dimensional surface which represents all of the data. The surface can be represented as the product of a function of geometric scale, and a function of pressure. The function of pressure appears to be the same in any configuration.

Nucleate Pool Boiling on Ribbed Surfaces With Micro-Roughness at Low and Moderate Heat Flux

1999 ◽  
Vol 121 (2) ◽  
pp. 376-385 ◽  
Author(s):  
S.-S. Hsieh ◽  
C.-J. Weng ◽  
J.-J. Chiou
Keyword(s):  
Heat Flux ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Nucleation Site ◽  
Nucleate Pool Boiling ◽  
Site Density ◽  
R 134A ◽  
Microlayer Evaporation ◽  
Two Parameters ◽  
Nucleation Site Density

Nucleate pool boiling correlation was developed for five different rib-type roughened tube geometries (including plain tube) with different rib angles of 30 deg, 45 deg, 60 deg, and 90 deg for both distilled water and R-134a as the working media. A scanning electron micrograph (SEM) examination was made for these horizontal roughened tubes. Bubble departure diameter, frequency of bubble emission, and the active nucleation site density with the influence of the rib angle for this type of roughened surface were obtained. Boiling heat flux incorporating natural convection, nucleate boiling, and microlayer evaporation mechanisms following Benjamin and Balakrishnan (1996) was predicted. Heat transfer correlation was also developed in terms of the degree superheat and active nucleation site density. The dependence for these two parameters was found in favorable agreement with that of previous study for smooth surfaces.

Photographic Study of Nucleate Pool Boiling on a Horizontal Surface

1965 ◽  
Vol 87 (1) ◽  
pp. 17-27 ◽  
Author(s):  
R. F. Gaertner
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Active Sites ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Copper Surface ◽  
Horizontal Surface ◽  
Transfer Model ◽  
Nucleate Pool Boiling ◽  
Platinum Surface

A photographic study was made of saturated nucleate pool boiling at a pressure of one atmosphere. Over 1000 still photographs and 12 high-speed motion pictures were taken of water boiling from a 2-in-dia flat horizontal surface facing upward. Two surfaces were studied, a 2/0 polished platinum surface and a 4/0 polished copper surface. The platinum surface was studied in the heat flux range of 14,700 to 176,000 Btu/hr, sq ft, and the copper surface from the incipient boiling heat flux of 10,500 Btu/hr, sq ft to the maximum flux of 493,000 Btu/hr, sq ft. Data were obtained for the breakoff diameters of discrete bubbles, and for the populations of active sites at heat fluxes up to 58,600 Btu/hr, sq ft. At least three, and possibly four, heat-transfer regions were found to exist in nucleate boiling, depending upon the mode of vapor generation. The vapor structures on the surface progressed through a sequence of first discrete bubbles, then vapor columns and vapor mushrooms, and finally vapor patches, as the surface temperature was increased. These individual vapor structures, or combinations of them, determine the mechanism of heat transfer in the four nucleate boiling regions. It was concluded that any heat-transfer model or design equation which is based on the dynamics of individual bubbles, or on any other single mechanism, must be in serious error.

The Mechanism of and Stability Criterion for Nucleate Pool Boiling of Sodium

1969 ◽  
Vol 91 (3) ◽  
pp. 315-328 ◽  
Author(s):  
I. Shai ◽  
W. M. Rohsenow
Keyword(s):  
Heat Flux ◽  
Liquid Metals ◽  
Bubble Formation ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Nucleate Pool Boiling ◽  
Thermal Layer ◽  
Minimum Heat ◽  
Bubble Growth And Departure ◽  
Recorded Temperature

Experimental data for sodium boiling on horizontal surfaces containing artificial cavities at heat fluxes of 20,000 to 300,000 Btu/ft2 hr and pressures between 40 to 106 mm Hg were obtained. Observations are made for stable boiling, unstable boiling and “bumping.” Some recorded temperature variations in the solid close to the nucleating cavity are presented. It is suggested that for liquid metals the time for bubble growth and departure is a very small fraction of the total bubble cycle, hence the delay time during which a thermal layer grows is the most significant part of the process. On this basis the transient conduction heat transfer is solved for a periodic process, and the period time is found to be a function of the degree of superheat, the heat flux and the liquid thermal properties. A simplified model for stability of nucleate pool boiling of liquid metals is postulated from which the minimum heat flux for stable boiling can be found as a function of liquid-solid properties, liquid pressure, the degree of superheat, and the cavity radius and depth. At relatively low heat fluxes, convection currents have significant effects on the period time of bubble formation. An empirical correlation is proposed, which takes into account the convection effects, to match the experimental results.

Boiling Heat Transfer and Critical Heat Flux Enhancement of Upward- and Downward-Facing Heater in Nanofluids

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Muhamad Zuhairi Sulaiman ◽  
Masahiro Takamura ◽  
Kazuki Nakahashi ◽  
Tomio Okawa
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Flux Enhancement ◽  
Optimum Configuration ◽  
Wall Superheat ◽  
Nucleate Boiling Heat Transfer

Boiling heat transfer (BHT) and critical heat flux (CHF) performance were experimentally studied for saturated pool boiling of water-based nanofluids. In present experimental works, copper heaters of 20 mm diameter with titanium-oxide (TiO2) nanocoated surface were produced in pool boiling of nanofluid. Experiments were performed in both upward and downward facing nanofluid coated heater surface. TiO2 nanoparticle was used with concentration ranging from 0.004 until 0.4 kg/m3 and boiling time of tb = 1, 3, 10, 20, 40, and 60 mins. Distilled water was used to observed BHT and CHF performance of different nanofluids boiling time and concentration configurations. Nucleate boiling heat transfer observed to deteriorate in upward facing heater, however; in contrast effect of enhancement for downward. Maximum enhancements of CHF for upward- and downward-facing heater are 2.1 and 1.9 times, respectively. Reduction of mean contact angle demonstrate enhancement on the critical heat flux for both upward-facing and downward-facing heater configuration. However, nucleate boiling heat transfer shows inconsistency in similar concentration with sequence of boiling time. For both downward- and upward-facing nanocoated heater's BHT and CHF, the optimum configuration denotes by C = 400 kg/m3 with tb = 1 min which shows the best increment of boiling curve trend with lowest wall superheat ΔT = 25 K and critical heat flux enhancement of 2.02 times.

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