scholarly journals Pool Boiling in an Accelerating System

1961 ◽  
Vol 83 (3) ◽  
pp. 233-242 ◽  
Author(s):  
Herman Merte ◽  
J. A. Clark
Keyword(s):  
Heat Flux ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Preliminary Analysis ◽  
Pool Boiling ◽  
Heating Surface ◽  
Theoretical Description ◽  
Distilled Water ◽  
Vapor Bubbles ◽  
High Acceleration

A study is reported of the influence of system acceleration (1 to 21 g) on pool boiling heat transfer using distilled water at approximately atmospheric pressure. The acceleration of the system is such that the resulting force field is normal to the heating surface, thereby increasing the buoyant forces acting on the vapor bubbles. Heat-flux rate is varied from approximately 5000 Btu/hr-sq ft (nonboiling) to 100,000 Btu/hr-sq ft. Data are presented for the influence of subcooling with the boiling system under acceleration at the lower values of heat flux. A preliminary analysis is presented for a theoretical description of the process of boiling under the influence of high acceleration, including the simultaneous effect of natural convection.

scholarly journals Discussion of the Heat Flux Calculation Method During Pool Boiling on Meshed Heaters

2020 ◽  
Vol 2 (1) ◽  
pp. 247-252
Author(s):  
Łukasz J. Orman ◽  
Norbert Radek ◽  
Jacek Pietraszek ◽  
Dariusz Gontarski
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Distilled Water ◽  
Determination Method ◽  
Nucleate Boiling Heat Transfer ◽  
Calculation Results ◽  
Very High

AbstractThe paper discusses nucleate boiling heat transfer on meshed surfaces during pool boiling of distilled water and ethyl alcohol of very high purity. It presents a correlation for heat flux developed for heaters covered with microstructural coatings made of meshes. The experimental results have been compared with the calculation results performed using the correlation and have been followed by discussion. Conclusions regarding the heat flux determination method have been drawn with the particular focus on the usefulness of the considered model for heat flux calculations on samples with sintered mesh layers.

Effect of Bubble Stabilization on Pool Boiling Heat Transfer

1970 ◽  
Vol 92 (4) ◽  
pp. 635-640 ◽  
Author(s):  
G. M. Fuls ◽  
G. E. Geiger
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Difference ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heating Surface ◽  
Liquid Column ◽  
Experimental Results ◽  
Pool Boiling Heat Transfer ◽  
Per Se

It is an established phenomenon that bubbles can be stabilized in a vertically vibrating liquid column. The effect of bubble stabilization on the rate of pool boiling heat transfer is experimentally investigated. With the liquid and heating surface vibrating as a unit, the data indicates a decrease of up to 12 percent in the temperature difference necessary for a given heat flux within the range of frequencies from 200 to 300 cps. The experimental results and comparison with results of previous investigators show that the effect is unique and not due simply to the vibrations per se.

Characteristics of Pool Boiling Bubble Dynamics in Bead Packed Porous Structures

2009 ◽  
Author(s):  
Calvin H. Li ◽  
Ting Li ◽  
Paul Hodgins ◽  
G. P. Peterson
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Heating Surface ◽  
Theoretical Models ◽  
Porous Structures ◽  
Pool Boiling Heat Transfer ◽  
Simulation Results

Spherical glass and copper beads have been used to create bead packed porous structures for an investigation of two-phase heat transfer bubble dynamics under geometric constraints. The results demonstrated a variety of bubble dynamics characteristics under a range of heating conditions. At low heat flux of 18.9 kW/m2, a single spherical bubble formed at nucleation sites of a heating surface and departed to the interstitial spaces of porous structure. When heat flux increased to 47 kW/m2, a single bubble grew into a Y shape between beads layers and connected with others to generate a horizontal vapor column. As heat flux reached 76.3 kW/m2, vertical vapor columns obtained strong momentum to form several major vapor escaping arteries, and glass beads were pushed upward by the vapor in the escaping arteries. According to Zuber’s hydrodynamics theory, choking will take place when the size of vapor columns reaches a certain value that is comparable to the critical hydrodynamic wavelength of the vapor column in plain surface pool boiling. The experimental and simulation results of this investigation illustrated that, under the geometric constrains of bead packed porous structures, similar characteristics had been induced to trigger the earlier occurrence of vapor column chocking inside porous structures. The bubble generation, growth, and detachment during the nucleate pool boiling heat transfer have been filmed, the heating surface temperatures and heat flux were recorded, and theoretical models have been employed to study bubble dynamic characteristics. Computer simulation results were combined with experimental observations to clarify the details of the vapor bubble growth process and the liquid water replenishing the inside of the porous structures. This investigation has clearly shown, with both experimental and computer simulation evidence, that the millimeter scale bead packed porous structures could greatly influence pool boiling heat transfer by forcing a single bubble to depart at a smaller size as compared to that in a plain surface situation at low heat flux situations, and could trigger the earlier occurrence of critical heat flux (CHF) by trapping the vapor into interstitial space and forming a vapor column net. The results also proved data for further development of theoretical models of pool boiling heat transfer in bead packed porous structures.

Photographic Study of Subcooled Pool Boiling Critical Heat Flux on Horizontal Cylinders With Commercial and Rough Surfaces

2013 ◽  
Author(s):  
Min Han Htet ◽  
Katsuya Fukuda ◽  
Qiusheng Liu
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Atmospheric Pressure ◽  
High Pressures ◽  
Pool Boiling ◽  
Vapor Bubbles ◽  
Spontaneous Nucleation ◽  
Transfer Processes ◽  
Horizontal Cylinders ◽  
Low Pressures

The subcooled pool boiling critical heat flux (CHF) using a 1.2-mm diameter horizontal commercial surface cylinder in water at pressures ranging from atmospheric pressure up to 2063 kPa for a wide ranges of liquid subcoolings from zero to 80 K have been measured to investigate for the mechanisms of subcooled boiling CHF depending on the effects of subcoolings and pressures on the steady and transient CHF. The steady-state CHFs for subcooling were divided into two groups for low and high subcoolings with pressure as a parameter with two different CHF mechanisms resulting from hydrodynamics instability (HI) and heterogeneous spontaneous nucleation (HSN). It was also observed that the measured CHFs resulting from the HI at low pressures in liquid subcoolings as well as the measured CHFs due to HSN at high pressures in high subcoolings respectively on a 1.2-mm diameter of commercial and rough (CS and RS) surface cylinders were approximately same with one another independently of surface conditions. The purpose of the present work is to investigate and compare the heat transfer processes and the vapor behaviors for two mechanisms of subcooled CHFs for the liquid subcooling of 20 K at 101.3 kPa and for the liquid subcooling of 80 K at 690 kPa by mean of photographically. The vapor behavior such as periodic bubble growths and detachments corresponding to HI mechanism at CHF for the liquid subcooling of 20 K at 101.3 kPa and small vapor bubbles existing for some periods on the cylinder corresponding to the HSN mechanism at CHF for the liquid subcooling of 80 K at 690 kPa were investigated.

Experimental and Mechanism Investigation on Boiling Heat Transfer Characteristics of Alumina/Water Nanofluid on a Cylindrical Tube

NANO ◽  
2019 ◽  
Vol 14 (10) ◽  
pp. 1950124
Author(s):  
Hao Zhang ◽  
Zeng-en Li ◽  
Shan Qing ◽  
Zhuangzhuang Jia ◽  
Jiarui Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Particle Deposition ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
Heating Surface ◽  
Cylindrical Tube ◽  
Influential Factors ◽  
Transfer Performance ◽  
Pool Boiling Heat Transfer

Nucleate pool boiling heat transfer experiments have been conducted to nanofluids on a horizontal cylinder tube under atmospheric pressure. The nanofluids are prepared by dispersing Al2O3 nanoparticles into distilled water at concentrations of 0.001, 0.01, 0.1, 1 and 2[Formula: see text]wt.% with or without sodium, 4-dodecylbenzenesulfonate (SDBS). The experimental results showed that: nanofluids at lower concentrations (0.001[Formula: see text]wt.% to 1[Formula: see text]wt.%) can obviously enhance the pool boiling heat transfer performance, but signs of deterioration can be observed at higher concentration (2[Formula: see text]wt.%). The presence of SDBS can obviously enhance the pool boiling heat transfer performance, and with the presence of SDBS, a maximum enhancement ratio of BHTC of 69.88%, and a maximum decrease ratio of super heat of 41.12% can be found in Group NS5 and NS4, respectively. The tube diameter and wall thickness of heating surface are the influential factors for boiling heat transfer coefficient. Besides, we find that Rohsenow formula failed to predict the characteristics of nanofluids. The mechanism study shows that: the decrease of surface tension, which leads to the decrease of bubble departure diameter, and the presence of agglomerates in nanofluids are the reasons for the enhanced pool boiling heat transfer performance. At higher concentration, particle deposition will lead to the decrease of distribution density of the vaporization core, and as a result of that, the boiling heat transfer performance will deteriorate.

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