Investigation of boiling heat transfer in water using a free-particles-based enhancement technique

Kim, Tae Young; Garimella, Suresh V.

doi:10.1016/j.ijheatmasstransfer.2013.12.071

Cited by 14 publications

(8 citation statements)

References 44 publications

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“…The results obtained in the present study for the wetting fluid FC-72 differ from the behavior observed with water in a companion paper [38]. While the trend of variation with particle size is similar, the optimum particle size at which the nucleate boiling heat transfer coefficient is maximized is significantly smaller for FC-72, on the order tens of microns.…”

Section: Effect Of Working Fluid Propertiescontrasting

confidence: 79%

“…Thus, smaller cavities would be expected to be preferred for nucleation in FC-72. Based on the results of the present study and those in [38], it is found that the effect of wetting holds true for the free particle technique, for which narrow corner cavities formed between the free particles and the heated surface serve as nucleation sites.…”

Section: Effect Of Working Fluid Propertiessupporting

confidence: 56%

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A free-particles-based technique for boiling heat transfer enhancement in a wetting liquid

Kim

Weibel

Garimella

2014

International Journal of Heat and Mass Transfer

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An easy-to-implement technique for pool boiling heat transfer enhancement is proposed and evaluated through an experimental investigation. This free-particle technique brings about nucleate boiling at a low degree of superheat by means of metal particles that are not fixed to the heated surface, but rather are free to move with respect to the surface. The effects of copper particles with sizes ranging from tens of nanometers to 9 mm on nucleate boiling heat transfer and critical heat flux (CHF) of the wetting dielectric fluid FC-72 are investigated. Visualizations of the bubble nucleation characteristics due to the free particles are presented. Experimental results show that the introduction of microscale free particles onto a superheated surface effectively facilitates bubble nucleation and thus increases the nucleate boiling heat transfer coefficients. Millimeter-sized as well as nanoscale free particles do not have a strong effect on the boiling heat transfer performance of this wetting fluid. Introduction of a large quantity of microscale free particles reduces CHF by increasing the resistance to liquid replenishment and vapor departure; however, by properly selecting particle size and quantity, an improvement in both nucleate boiling heat transfer and CHF is observed. For the case where 0.2 g of 10 μm-diameter free particles are placed on a polished copper surface, corresponding to a particle layer thickness of approximately 67 μm, the average nucleate boiling heat transfer coefficient is enhanced by 76.3% over the heat flux range of 10 to 159 kW/m 2 , while CHF is increased by 10%.

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Section: Effect Of Working Fluid Propertiescontrasting

confidence: 79%

Section: Effect Of Working Fluid Propertiessupporting

confidence: 56%

A free-particles-based technique for boiling heat transfer enhancement in a wetting liquid

Kim

Weibel

Garimella

2014

International Journal of Heat and Mass Transfer

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“…The mechanism by which heat transfer is enhanced upon the addition of free particles during pool boiling is by creation of surface cavity geometries that are favorable for vapor nucleation [28,29] The parametric effects of free-particle size on pool boiling performance are investigated with particle diameters ranging from 45 µm to 1000 µm and compared against the polished surface baseline case; layer thickness is maintained at a constant value of 4.8 particle diameters for all cases. The boiling curves obtained are shown in Figure 4.…”

Section: Free-particle Coatingmentioning

confidence: 99%

“…As distinct from the techniques discussed above, the placement of loose copper particles on a heated surface has been recently explored as a technique for pool boiling heat transfer enhancement by Kim et al [28,29]. This free-particle technique utilizes copper particles that are not attached to the heated surface to provide additional nucleation sites during pool boiling.…”

Section: Introductionmentioning

confidence: 99%

“…This free-particle technique utilizes copper particles that are not attached to the heated surface to provide additional nucleation sites during pool boiling. High-speed flow visualization revealed that preferential bubble nucleation sites were formed at the corner cavities between the free particles and the heated surface, similar to sintered surfaces, causing enhancement of pool boiling heat transfer coefficient [28]. The effects of particle size, number of particles, and fluid properties were studied.…”

Section: Introductionmentioning

confidence: 99%

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

Sarangi

Weibel

Garimella

2015

International Journal of Heat and Mass Transfer

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133

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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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Experiment Analysis of Pool Boiling Heat Transfer in Bead Packed Porous Layers

Chen

Wang

2015

Heat Trans. Asian Res.

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The heat transfer of pool boiling in bead packed porous layers was experimentally investigated to analyze the effects of the bead material, bead diameter and the layer number of the porous bed on the transport of flux and the heat transfer coefficients. The glass and copper bead, the bead sizes of 4 mm and 6 mm as well as the bead packed porous structures ranging from one to three layers were chosen in the experiments. The pool boiling heat transfer in the bead packed porous structures and that on the plain surface were compared to analyze the enhancement of pool boiling heat transfer while the bead packed porous layers were employed. The maximum relative error between the collected experimental data of the pure water on a plain surface and the theoretical prediction of pool boiling using the Rohsenow correlation was less than 12%. Besides, the boiling bubble generation, integration and departure have a great effect on the pool boiling and were recorded with a camera in the bead stacked porous structures of the different layers and materials at different heat flux. All these results should be taken into account for the promotion and application of bead packed porous structures in pool boiling to enhance the heat transfer.

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Investigation of boiling heat transfer in water using a free-particles-based enhancement technique

Cited by 14 publications

References 44 publications

A free-particles-based technique for boiling heat transfer enhancement in a wetting liquid

A free-particles-based technique for boiling heat transfer enhancement in a wetting liquid

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

Experiment Analysis of Pool Boiling Heat Transfer in Bead Packed Porous Layers

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