Pool Boiling Heat Transfer From Enhanced Surfaces to Dielectric Fluids

1982 ◽  
Vol 104 (2) ◽  
pp. 292-299 ◽  
Author(s):  
P. J. Marto ◽  
V. J. Lepere
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Past History ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Test Surface ◽  
High Flux ◽  
Flux Surface ◽  
Pool Boiling Heat Transfer ◽  
Dielectric Fluids

Pool boiling heat-transfer measurements were made using a 15.8 mm o.d. plain copper tube and three copper enhanced surfaces: a Union Carbide High Flux surface, a Hitachi Thermoexcel-E surface and a Wieland Gewa-T surface. The dielectric fluids were Freon-113 and Fluorinert FC-72, a perfluorinated organic compound manufactured to cool electronic equipment. Data were taken at atmospheric pressure, and at heat fluxes from 100 W/m2 to 200,000 W/m2. Prior to operation, each test surface was subjected to one of three aging procedures to observe the effect of surface past history upon boiling incipience. For Freon-113 the enhanced surfaces showed a two to tenfold increase in the heat-transfer coefficient when compared to a plain tube, whereas for FC-72 an increase of two to five was measured. The High Flux surface gave the best performance over the range of heat fluxes. The Gewa-T surface did not show as much of an enhancement at low fluxes as the other two surfaces, but at high fluxes its performance improved. In fact, it was the only surface tested which delayed the onset of film boiling with FC-72. The degree of superheat required to activate the enhanced surfaces was sensitive to both past history of the surface and to fluid properties.

Pool Boiling Heat Transfer Enhancement of Water by Gold Nanoparticles With an Electrophoretic Deposition Method

2018 ◽  
Author(s):  
Zhen Cao ◽  
Anh Duc Pham ◽  
Zan Wu ◽  
Tautgirdas Ruzgas ◽  
Cathrine Alber ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gold Nanoparticles ◽  
Electrophoretic Deposition ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Electrical Potential ◽  
Heat Fluxes ◽  
Deposition Method ◽  
Pool Boiling Heat Transfer ◽  
Modified Surfaces

Saturated pool boiling heat transfer of water is investigated experimentally on copper surfaces with nanoparticle coatings at atmospheric pressure. The coatings are generated by an electrophoretic deposition method (EPD). Three modified surfaces are prepared with gold nanoparticles of 0.20 mg, 0.25 mg and 0.30 mg, respectively. During the deposition, ethanol works as the solvent while the electrical potential and deposition time are controlled as 9.5 V and 30 min, respectively. The experimental results show that heat transfer coefficients (HTC) and critical heat fluxes (CHF) are enhanced on the modified surfaces. HTC increases with decreasing thickness of the coating, while CHF increases with increasing thickness of the coating. CHFs of EPD-0.20 mg, EPD-0.25 mg and EPD-0.30 mg are 93 W/cm2, 123 W/cm2 and 142 W/cm2, respectively, which are increased by 7%, 41% and 63% compared with the smooth surface. EPD-0.20 mg performs the best on heat transfer, with a maximum enhancement of around 60%. At the end, a brief review about mechanistic models of heat transfer at low and moderate heat fluxes is provided, based on which, the reasons why heat transfer is enhanced are discussed.

scholarly journals Pool boiling heat transfer for surfaces with microchannels of variable depth

2019 ◽  
Vol 213 ◽  
pp. 02063
Author(s):  
Robert Pastuszko ◽  
Milena Bedla-Pawlusek ◽  
Robert Kaniowski
Keyword(s):  
Heat Transfer ◽  
Bubble Growth ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Experimental Investigations ◽  
Variable Depth ◽  
Transfer Coefficients ◽  
Base Surface ◽  
Pool Boiling Heat Transfer

Experimental investigations of pool boiling heat transfer on microchannels of variable depth were conducted. The experiments were carried out for water and ethanol at atmospheric pressure. Microchannels of variable depth from 0.2 to 2.8 mm and width 0.5 mm were uniformly spaced on base surface with pitch of 1 mm. The comparison of heat transfer coefficients for surfaces with variable and constant depth of microchannels was made. At the low and medium heat fluxes structures with constant microchannel depth showed the best boiling heat transfer performance. EX-FH20 (Casio) camera was used to record the images of the entire surface of the specimen. The bubble growth mechanism on the enhanced surface was different from that of plain surface. Visualization investigations were aimed at identifying nucleation sites and determining the bubble growth cycle. Vapor bubbles generate in microchannel spaces, from where they move towards the fin tips, then grow and depart.

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