Diameter Effects on Nucleate Pool Boiling for a Vertical Tube

2000 ◽  
Vol 123 (2) ◽  
pp. 400-404 ◽  
Author(s):  
Myeong-Gie Kang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Vertical Tube ◽  
Nucleate Pool Boiling ◽  
Vertical Orientation ◽  
The Heat Transfer Coefficient ◽  
Good Agreement

Diameter effects on nucleate pool boiling heat transfer for a tube with vertical orientation have been obtained experimentally. According to the results (1) the heat transfer coefficient decreases as the tube diameter increases and the trend is more notable with a rougher surface, and (2) the experimental data is in good agreement with the Cornwell and Houston’s correlation within a ±20 percent scatter range.

A FRACTAL ANALYSIS OF SUBCOOLED NUCLEATE POOL BOILING

Fractals ◽  
2008 ◽  
Vol 16 (01) ◽  
pp. 1-9 ◽  
Author(s):  
BOQI XIAO ◽  
ZONGCHI WANG ◽  
BOMING YU
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Fractal Model ◽  
Nucleate Pool Boiling ◽  
Empirical Constant ◽  
Pool Boiling Heat Transfer ◽  
Model Predictions ◽  
Conventional Models

A fractal model for the subcooled nucleate pool boiling heat transfer is proposed in this paper. The analytical expressions for the subcooled nucleate pool boiling heat transfer are derived based on the fractal distribution of nucleation sites on boiling surfaces. The proposed fractal model for the subcooled nucleate pool boiling heat transfer is found to be a function of wall superheat, liquid subcooling, fractal dimension, the minimum and maximum active cavity size, the contact angle and physical properties of fluid. No additional/new empirical constant is introduced, and the proposed model contains less empirical constants than the conventional models. The model predictions are compared with the existing experimental data, and fair agreement between the model predictions and experimental data is found for different liquid subcoolings.

Experimental and Numerical Study of Nucleate Pool Boiling Heat Transfer and Bubble Dynamics in Saline Solution

2020 ◽  
Author(s):  
Qi Liu ◽  
Yuxin Wu ◽  
Yang Zhang ◽  
Junfu Lyu
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Saline Solution ◽  
Numerical Study ◽  
Pool Boiling ◽  
Pool Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient

Abstract A visual pool boiling experimental device based on ITO coating layer heater and high-speed shooting technology was established for studying the bubble behavior and heat transfer characteristics of saline solution, which is of great significance for ensuring heat transfer safety in nuclear power plants, steam injection boilers and seawater desalination. Volume of fluid method was applied to simulate numerically the liquid–vapor phase change by adding source terms in the continuity equation and energy equation. The predictions of the model are quantitatively verified against the experimental data. It can be found based on the experimental data that the pool boiling heat transfer coefficient is enhanced as the salt concentration increases. Visualization studies and numerical data have shown that the presence and precipitation of salt leads to a decrease in the detachment diameter and growth time of the bubble and an increase in the frequency of detachment, thereby increasing the pool boiling heat transfer coefficient.

Efficacy of Microscopic Interconnected Channels and Surfactants on Enhancing Pool Boiling Heat Transfer

2007 ◽  
Author(s):  
Rene Reyes Mazzoco
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Bubble Diameter ◽  
Pool Boiling ◽  
Liquid Mixtures ◽  
Vapor Flow ◽  
Pool Boiling Heat Transfer ◽  
The Heat Transfer Coefficient

Nucleate pool boiling heat transfer increases with certain liquid mixtures and some coatings over the heater’s surface. The effects of these modifications are best measured by the relative values of the convective heat transfer coefficient that quantify the ability for transferring heat. The mechanisms that increase pool boiling heat transfer are reflected in the formation of smaller bubbles that escape away from the heater’s surface at a higher velocity, than those formed under not enhanced conditions. The bubble diameter depends on a chemical effect from the liquid composition acting at the bubble’s interface, and on the physical effect of the porous coverings to break the bubbles and to allow the resulting vapor flow. The reduction in bubble diameter in liquid mixtures comes from the action of intermolecular forces at the liquid-vapor interface similar to those associated to surfactants. Several studies have concentrated on increasing the heat transfer coefficient in pool using surfactants in concentrations close to the critical micelle concentration (cmc) of the surfactant in the liquid. The surfactants achieve the highest reduction of bubble diameter by accommodating the lowest surface of their molecules at the interface. However, the mixture of 16% ethanol in water also showed an increase in the convective heat transfer coefficient by producing the lowest size of bubbles from any other ethanol-water mixture. Surface tension and sessile drop contact angle for this mixture have a behavior similar to the cmc; therefore, the mixture effect on boiling is explained through the presence of ethanol-hydrated-states accommodated at the interface. Other liquid mixtures, containing propylene glycol, ethylene glycol, ethanol and water, with cmc behavior had been found through surface tension and sessile contact angle measurements, and showed that they increased the heat transfer coefficient. The mechanical effect that increases the heat transfer coefficient with porous coverings has been explained as the breaking of emerging bubbles at the heater’s surface and the proper handling of the resulting vapor flow away from the covering. Experiments with a mesh located at a distance half the bubble diameter, at a specific power supplied, released the bubbles from the heater before finishing its formation increasing their departure frequency. An array of layers of the same mesh produced and additional increment in the heat transfer coefficient if the array is accommodated to favor the gas flow out of the heater’s region.

Experimental investigations on nucleate pool boiling over micro-finned cylindrical surfaces

2022 ◽  
pp. 095440622110627
Author(s):  
Balkrushna Shah ◽  
Kathit Shah ◽  
Parth Patel ◽  
Vikas J Lakhera
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Dimensional Analysis ◽  
Heat Exchangers ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Experimental Investigations ◽  
Boiling Heat Transfer Coefficient

The nucleate pool boiling heat transfer over micro-finned cylindrical surfaces has application in the heat exchangers used in thermal power plants and chemical industries. The estimation of boiling heat transfer coefficient is an important parameter in the design of two-phase heat exchangers using micro-finned cylindrical surfaces. In the present work, related experimental investigations on four micro-finned cylindrical surfaces with different surface geometry using refrigerant R-141b at atmospheric pressure are conducted to determine the boiling heat transfer coefficient over micro-finned cylindrical surfaces. A correlation is developed by dimensional analysis wherein the effects of geometrical parameters, operating pressure and thermo-physical properties of fluids are taken into consideration and dimensional analysis conducted using Buckingham π-theorem. The correlation developed utilizes experimental data obtained over the present study as well as from previous studies by various researchers including experimental data for water over different micro-finned cylindrical surfaces at 1 bar by Mehta and Kandlikar, experimental data for R123 at 0.97 bar by Saidi et al. and experimental data for R134a over micro-finned cylindrical surface at 6.1 bar, 8.1 bar, 10.1 bar and 12.2 bar by Rocha et al. The heat flux ranging from 5 to 1100 kW/m2 are considered for the analysis. The data points have been compared with the proposed correlation and the absolute average deviation of the whole data set was obtained as 13.43% with root mean square deviation of 0.0273. All the predicted values were within ±15% of the experimental values of the boiling heat transfer coefficient.

Nucleate Pool Boiling Heat Transfer Measurement and Flow Visualization for Ammonia-Water Mixture

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
A. Sathyabhama ◽  
T. P. Ashok Babu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Mass Fraction ◽  
Pool Boiling ◽  
Bubble Nucleation ◽  
Water Mixture ◽  
Nucleate Pool Boiling ◽  
Ammonia Water

Visualization of bubble nucleation during nucleate pool boiling outside a vertical cylindrical heated surface was done for ammonia-water binary mixture in order to obtain a descriptive behavior of the boiling, which was directly compared with the measured heat transfer coefficient data at low pressure of 4–8 bar and at low mass fraction of 0 < x < 0.3 and at different heat flux. Still images taken with high speed camera are used to demonstrate the decrease in boiling heat transfer coefficient with increase in ammonia mass fraction. Jensen and Memmel model has better agreement with experimental bubble diameter. Further work is required to obtain quantitative information about bubble nucleation parameters. It is found that both Calus and Rice and Stephan–Koorner correlation can predict the experimental heat transfer coefficient values with a maximum deviation of ± 20%.

scholarly journals AN EXPERIMENTAL STUDY OF THE EFFECT OF SURFACTANT AND TI02 NANOPARTICLES ADDITIVES IN R141B ON THE NUCLEATE POOL BOILING PROCESS

2017 ◽  
Vol 39 (5) ◽  
pp. 37-40
Author(s):  
O. Khliyeva ◽  
T. Gordeychuk ◽  
A. Nikulin ◽  
N. Lukianov ◽  
V. Zhelezny
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Tio2 Nanoparticles ◽  
Pool Boiling ◽  
Nucleate Pool Boiling ◽  
Boiling Process ◽  
The Heat Transfer Coefficient

The results of experimental study of effect of TiO2 nanoparticles (0.1 % mass.) and surfactant Span80 (0.1 % mass.) additives in refrigerant R141b on the heat transfer coefficient of nucleate pool boiling process at three values of pressure 0.2, 0.3 and 0.4 MPa and range of heat flux from 5 to 70 kWm-2 are presented in paper.  

scholarly journals Prediction of nucleate pool boiling heat transfer coefficient

2010 ◽  
Vol 14 (2) ◽  
pp. 353-364 ◽  
Author(s):  
Alangar Sathyabhama ◽  
Ramakrishna Hegde
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Correct Prediction ◽  
Nucleate Pool Boiling ◽  
Successful Operation ◽  
Refrigeration Unit ◽  
Boiling Heat Transfer Coefficient

The correct prediction of the heat transfer performance of the boiling liquid within the evaporator of a refrigeration unit is one of the essential features for the successful operation of the whole unit. There are many correlations available in the literature for the prediction of boiling heat transfer coefficient of pure components. Eight heat transfer pool-boiling correlations that are well known in the literature have been selected and their prediction accuracy has been assessed against experimental data of ammonia available in the literature. The analysis concludes that within the investigated ranges of boiling conditions, the Kruzhilin, Kutateladze, Labuntsov, Mostinski nucleate pool-boiling correlations are the most accurate among those assessed.

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