Bubble Behavior in Pool Boiling Heat Transfer between Two Plates with a Narrow Gap

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Jin Sub Kim ◽  
Dong Hwan Shin ◽  
Yeonghwan Kim ◽  
Seung M. You ◽  
Jungho Lee
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Thin Liquid Film ◽  
Ground Plane ◽  
Pool Boiling ◽  
High Heat Flux ◽  
Narrow Gap ◽  
Bubble Behavior ◽  
Military Technology ◽  
Technology Cooperation

Abstract The pool boiling phenomena, which may occur at high heat flux in the planar heat pipe such as vapor chamber and thermal ground plane (TGP), were visually investigated in the vertical orientation by capturing the bubble behavior within a narrow gap between two plates using distilled water at 1 atm. The size of two copper plates is 80×80 mm2 and the 10×10 mm2 ceramic heater, which simulates the high power chip, was bonded to the backside of the bottom plate. The gap between two plates was adjusted from 3 mm to 0.5 mm using spacers. It was observed that the generated bubble spreads laterally throughout the channel between the plates as decreasing the gap. Thin liquid film forms beneath the flattened bubble and the thin film evaporation improves heat transfer at the narrow gaps of 3 and 1 mm. However, further reduction of the gap down to 0.5 mm brings about an increase of the dried region, resulting in the deterioration of boiling heat transfer. [This work was supported by the Civil-Military Technology Cooperation Program of the Institute of Civil-Military Technology Cooperation (ICMTC), with a grant funded by the Defense Acquisition Program Administration and the Ministry of Trade, Industry and Energy (Grant No. 18CM5017).]

Characteristics of Pool Boiling Bubble Dynamics in Bead Packed Porous Structures

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Calvin H. Li ◽  
Ting Li ◽  
Paul Hodgins ◽  
G. P. Peterson
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Computer Simulation ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Theoretical Models ◽  
High Heat Flux ◽  
Porous Structures ◽  
Pool Boiling Heat Transfer

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. 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 with that in a plain surface situation at low heat flux situations, and could trigger the earlier occurrence of critical heat flux by trapping the vapor into interstitial space and forming a vapor column net at high heat flux situations. The results also proved data for further development of theoretical models of pool boiling heat transfer in bead packed porous structures.

Pool Boiling Heat Transfer on Vertical Micro Porous Coated Surface in Confined Space

2008 ◽  
Author(s):  
Chien-Yuh Yang ◽  
Chien-Fu Liu
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Confined Space ◽  
Pool Boiling Heat Transfer ◽  
Coated Surface

Attributed to its high heat transfer coefficient, evaporating cooling involving the use of micro heat exchangers is considered a possible thermal management solution for cooling of high heat flux electronic devices. The present work desires to develop high-performance micro heat exchangers operating in the evaporation regime. The pool boiling heat transfer performance on one plain plate and one micro porous coated plate were tested in a vertical open and a 1-mm confined spaces. The test results show that the heat transfer was enhanced by the confined space at low and moderate heat fluxes but degraded at high flux condition on plain surface. The micro porous coating may significantly enhance the pool boiling performance. However, the heat transfer characteristic in confined space is not exactly the same as that on open surfaces. Owing to the interaction of forced removal of the superheated liquid due to the bubble departure and retard the departure of bubbles by the confined plate, there is no much difference for pool boiling heat transfer on micro porous coated surface in confined and unconfined spaces at low and moderate heat fluxes. At high heat flux, large amount of bubbles were confined by the cover plate. This caused the partial dry out and significant degrade on heat transfer performance.

Pool Boiling Heat Transfer Augmentation in a Novel Aqueous Binary Mixture of Surfactants

2020 ◽  
Author(s):  
Prashant Pawar ◽  
Abdul Najim ◽  
Anil Acharya ◽  
Ashok Pise
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Heat Flux ◽  
Binary System ◽  
Binary Mixture ◽  
Bubble Growth ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
High Heat Flux

Abstract This paper investigates the augmentation of heat transfer during pool boiling in a novel aqueous binary mixture of surfactants. The surfactants used were Sodium Dodecyl Sulphate (anionic), Centrimonium Bromide (cationic), and Nicotine (non-ionic). The aqueous binary mixtures SDS-CTAB, CTAB- Nicotine, and SDS-Nicotine were prepared on the volume percentage basis. The augmentation was investigated by studying a single bubble growth in an aqueous binary mixture of surfactants. The investigation was conducted at two values of heat fluxes to probe the effect of heat flux on bubble growth. A reduction in surface tension was attained by SDS-CTAB, CTAB-Nicotine, and SDS-Nicotine aqueous binary systems compared to its individual aqueous surfactant solutions at their optimum concentrations. The most significant surface tension result was obtained by the novel SDS-Nicotine aqueous binary system at 25:75 volume percentages. A decrement in the bubble departure diameter and an increment in the release frequency were observed for SDS-Nicotine aqueous binary system both heat fluxes. The boiling heat transfer coefficient of SDS-Nicotine aqueous binary system was found to be increased by 36.32% and 58.67% compared to saturated water at low and high heat flux, respectively.

Pool Boiling Heat Transfer of Water on Copper Surfaces With Nanoparticles Coating

2017 ◽  
Author(s):  
Zhen Cao ◽  
Calle Preger ◽  
Zan Wu ◽  
Sahar Abbood ◽  
Maria E. Messing ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Deposition Time ◽  
Pool Boiling ◽  
Working Fluid ◽  
High Heat Flux ◽  
Pool Boiling Heat Transfer

Saturated pool boiling heat transfer is investigated experimentally on a copper substrate with copper nanoparticle coatings at atmospheric pressure, in terms of critical heat flux (CHF) and heat transfer coefficient (HTC). Experiments are carried out on the substrate surface with a diameter of 12 mm using DI water as the working fluid. The coating is formed by stacking copper nanoparticles generated by an aerosol method. The aerosol nanoparticles are generated by a spark discharge generator with nitrogen gas as carrier gas and size-selected prior to electrostatic deposition. The thickness of the coating is quantified by the deposition time. In the present study, copper particles with diameter 35± 5 nm are selected, considering better coverage on the surface, while the deposition time is controlled as 4h and 8h, respectively. The boiling curves and heat transfer coefficient of MS-1 (4h deposition) and MS-2 (8h deposition) were compared with the BS (bare surface). The results show that CHFs of MS-1 and MS-2 are increased by 24% and 36%, respectively compared with the BS, while heat transfer is enhanced as well. High speed visualization tells that the coating provides more active nucleate sites and the hydrophobicity of the coating helps bubbles departure from the surface at low and moderate heat flux. At high heat flux, a hollow well occurs on MSs to supply liquid effectively to avoid dryout. Therefore, CHF and heat transfer are both improved.

Pool Boiling Heat Transfer and Bubble Dynamics Over Plain and Enhanced Microchannels

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Dwight Cooke ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Silicon Chips ◽  
Heat Of Evaporation

Pool boiling is of interest in high heat flux applications because of its potential for removing large amount of heat resulting from the latent heat of evaporation and little pressure drop penalty for circulating coolant through the system. However, the heat transfer performance of pool boiling systems is not adequate to match the cooling ability provided by enhanced microchannels operating under single-phase conditions. The objective of this work is to evaluate the pool boiling performance of structured surface features etched on a silicon chip. The performance is normalized with respect to a plain chip. This investigation also focuses on the bubble dynamics on plain and structured microchannel surfaces under various heat fluxes in an effort to understand the underlying heat transfer mechanism. It was determined that surface modifications to silicon chips can improve the heat transfer coefficient by a factor up to 3.4 times the performance of a plain chip. Surfaces with microchannels have shown to be efficient for boiling heat transfer by allowing liquid to flow through the open channels and wet the heat transfer surface while vapor is generated. This work is expected to lead to improved enhancement features for extending the pool boiling option to meet the high heat flux removal demands in electronic cooling applications.

Nucleate Pool Boiling Heat Transfer in Microgravity

1998 ◽  
Vol 29 (1-3) ◽  
pp. 196-207
Author(s):  
Haruhiko Ohta ◽  
Koichi Inoue ◽  
Suguru Yoshida ◽  
Tomoji S. Morita
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Pool Boiling ◽  
Pool Boiling Heat Transfer
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