Boiling heat transfer phenomena from microporous and porous surfaces in saturated FC-72

Chang, Joonho; You, Seungkwon

doi:10.1016/s0017-9310(97)00055-0

Cited by 200 publications

(74 citation statements)

References 10 publications

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“…These bubbles have less difficulty in displacing -and departing from -the particulate layer, leading to lower wall superheat as compared to the larger particle sizes. The difference compared to larger particles starts at heat fluxes higher than 25 kW/m 2 , as similarly observed for sintered coatings by Chang and You [25]. As the boiling process becomes more vigorous at these higher heat fluxes, visualization of the smaller 90-106 µm particles ( Figure 5 (c)) shows that nucleation sites remain active and uniform over the surface due to intermittent settling of particles, whereas nucleation was non-uniform and vapor was forced to depart through thick particulate layers for the comparatively larger 180-212 µm particles.…”

Section: Free-particle Coatingsupporting

confidence: 74%

“…Following a similar analysis as proposed by Hsu [26], the superheated liquid layer thickness for FC-72 was estimated to be 100 µm (as in [25]); however, due to the high thermal conductivity of the current sintered copper coating as compared to the epoxy-based porous coating in [25], the observed optimum coating thickness was higher for the present coating (~400 µm). Figure 8 shows a direct comparison between the boiling curves obtained for the free-particle and sintered-coating enhancement techniques.…”

Section: Sintered Particle Coatingsupporting

confidence: 56%

“…Chang and You [25] investigated boiling of FC-72 from a nonconductive epoxy-based porous surface, where the coating thickness increased with particle size. The heat transfer coefficient increased with an increase in particle size from 2 µm to 20 µm, but decreased with further increases in particle size.…”

Section: Sintered Particle Coatingmentioning

confidence: 99%

“…A similar increase compared to the predicted value was also observed by Scurlock [37], where the optimum coating thickness was 250 µm compared to the calculated superheated liquid layer thickness of 100 µm for liquid nitrogen. Chang and You [25] attributed this increased optimum thickness to the higher thermal conductivity of the plasma-sprayed aluminum particle coating.…”

Section: Sintered Particle Coatingmentioning

confidence: 99%

“…Chien and Chang [24] found a minimum thermal resistance for sintered copper powder layers in boiling water at an optimum coating thickness-to-particle diameter ratio of 3.85. The prediction of the optimum coating thickness was studied by Chang and You [25], and compared against experiments for boiling of FC-72 from surfaces coated with diamond particles. Based on an analysis that assumed a transient superheated liquid boundary layer to be formed above each nucleation site between successive bubble departures [26], an optimum coating thickness equal to the superheated liquid layer thickness was predicted.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Effect of particle size on surface-coating enhancement of pool boiling heat transfer

Sarangi

Weibel

Garimella

2015

International Journal of Heat and Mass Transfer

126

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The enhancement of pool boiling heat transfer by copper-particle surface coatings is experimentally investigated, using the wetting dielectric fluid FC-72. In one technique, loose copper particles are placed on a heated copper surface to provide additional vapor nucleation sites in the cavities formed at particlesurface and particle-particle contact points, thereby enhancing boiling performance over a polished surface. This 'free-particle' technique is benchmarked against the more traditional technique of sintering a fixed layer of copper particles to the surface to enhance boiling heat transfer performance. The effect of particle size on the heat transfer performance is studied for particle diameters ranging from 45 µm to 1000 µm at a constant coating layer thickness-to-particle diameter ratio of approximately 4. The parametric trends in the boiling curve and the critical heat flux are compared between the two techniques, and the dominant boiling mechanisms influencing these trends are compared and contrasted. High-speed visualizations are performed to qualitatively assess the boiling patterns and bubble departure size/distribution, and thus corroborate the trends observed in the boiling curves. The measured wall superheat is significantly lower with a sintered coating compared to the free-particle layer for any given particle size and heat flux. Performance trends with respect to particle size, however, are remarkably similar for both enhancement techniques, and an optimum particle size of ~100 µm is identified for both free particles and sintered coatings. The free-particle technique is shown to offer a straightforward method to screen the boiling enhancement trends expected from different particulate layer compositions that are intended to be subsequently fabricated by sintering.

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Section: Free-particle Coatingsupporting

confidence: 74%

Section: Sintered Particle Coatingsupporting

confidence: 56%

Section: Sintered Particle Coatingmentioning

confidence: 99%

Section: Sintered Particle Coatingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of particle size on surface-coating enhancement of pool boiling heat transfer

Sarangi

Weibel

Garimella

2015

International Journal of Heat and Mass Transfer

126

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Bioinspired Surfaces for Enhanced Boiling

Zhu

Antao

Wang

2018

Bioinspired Engineering of Thermal Materials

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Nature‐Inspired Boiling Enhancement by Novel Nanostructured Macroporous Surfaces

Furberg

Toprak

et al. 2008

Adv Funct Materials

126

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World energy crisis has triggered more attention to energy saving and energy conversion systems. Enhanced surfaces for boiling are among the applications of great interest since they can improve the energy efficiency of heat pumping equipment (i.e., air conditioners, heat pumps, refrigeration machines). Methods that are used to make the state‐of‐the‐art enhanced surfaces are often based on complicated mechanical machine tools, are quite material‐consuming and give limited enhancement of the boiling heat transfer. Here, we present a new approach to fabricate enhanced surfaces by using a simple electrodeposition method with in‐situ grown dynamic gas bubble templates. As a result, a well‐ordered 3D macro‐porous metallic surface layer with nanostructured porosity is obtained. Since the structure is built based on the dynamic bubbles, it is perfect for the bubble generation applications such as nucleate boiling. At heat flux of 1 W cm‐2, the heat transfer coefficient is enhanced over 17 times compared to a plain reference surface. It's estimated that such an effective boiling surface would improve the energy efficiency of many heat pumping machines with 10–30%. The extraordinary boiling performance is explained based on the structure characteristics.

show abstract

Boiling heat transfer phenomena from microporous and porous surfaces in saturated FC-72

Cited by 200 publications

References 10 publications

Effect of particle size on surface-coating enhancement of pool boiling heat transfer

Effect of particle size on surface-coating enhancement of pool boiling heat transfer

Bioinspired Surfaces for Enhanced Boiling

Nature‐Inspired Boiling Enhancement by Novel Nanostructured Macroporous Surfaces

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