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Infrared thermometry study of nanofluid pool boiling phenomena.

Gerardi C, Buongiorno J, Hu LW, McKrell T - Nanoscale Res Lett (2011)

Bottom Line: The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat.Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces.Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave,, Cambridge, MA 02139 USA. jacopo@mit.edu.

ABSTRACT
Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement.

No MeSH data available.


Related in: MedlinePlus

Bubble parameter distributions for all DI water nucleation sites (Expt. 2, q"= 50 kW/m2). Shown are the distribution of (a) bubble departure diameter, (b) departure frequency, (c) ratio of bubble growth time to cycle time, and (d) the relationship between frequency and diameter for a given nucleation site.
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Figure 15: Bubble parameter distributions for all DI water nucleation sites (Expt. 2, q"= 50 kW/m2). Shown are the distribution of (a) bubble departure diameter, (b) departure frequency, (c) ratio of bubble growth time to cycle time, and (d) the relationship between frequency and diameter for a given nucleation site.

Mentions: There also is some variability in the bubble departure diameter, frequency, and growth and wait times between individual nucleation sites at a given heat flux (or superheat). While the individual nucleation site values were used in the analysis of the heat transfer coefficient and CHF models in the present paper, the ensemble averages for these parameters were discussed in "Experimental results" and reported in Figures 4,5,7,8 in order to allow quick comparison between the water and nanofluid data. In order to provide an example of the variability of bubble parameters across nucleation sites, the data for DI water (Expt. 2, q" = 50 kW/m2) is chosen again. For this experiment, the distribution of the bubble departure diameter, departure frequency, and ratio of bubble growth time to the cycle time are shown in Figure 15. Also shown in Figure 15d is the relationship between the frequency and departure diameter for each nucleation site for this experiment. There is a wide distribution in all of these parameters across the nucleation sites, significantly wider than for an individual nucleation site, suggesting that each nucleation site is fairly unique.


Infrared thermometry study of nanofluid pool boiling phenomena.

Gerardi C, Buongiorno J, Hu LW, McKrell T - Nanoscale Res Lett (2011)

Bubble parameter distributions for all DI water nucleation sites (Expt. 2, q"= 50 kW/m2). Shown are the distribution of (a) bubble departure diameter, (b) departure frequency, (c) ratio of bubble growth time to cycle time, and (d) the relationship between frequency and diameter for a given nucleation site.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211291&req=5

Figure 15: Bubble parameter distributions for all DI water nucleation sites (Expt. 2, q"= 50 kW/m2). Shown are the distribution of (a) bubble departure diameter, (b) departure frequency, (c) ratio of bubble growth time to cycle time, and (d) the relationship between frequency and diameter for a given nucleation site.
Mentions: There also is some variability in the bubble departure diameter, frequency, and growth and wait times between individual nucleation sites at a given heat flux (or superheat). While the individual nucleation site values were used in the analysis of the heat transfer coefficient and CHF models in the present paper, the ensemble averages for these parameters were discussed in "Experimental results" and reported in Figures 4,5,7,8 in order to allow quick comparison between the water and nanofluid data. In order to provide an example of the variability of bubble parameters across nucleation sites, the data for DI water (Expt. 2, q" = 50 kW/m2) is chosen again. For this experiment, the distribution of the bubble departure diameter, departure frequency, and ratio of bubble growth time to the cycle time are shown in Figure 15. Also shown in Figure 15d is the relationship between the frequency and departure diameter for each nucleation site for this experiment. There is a wide distribution in all of these parameters across the nucleation sites, significantly wider than for an individual nucleation site, suggesting that each nucleation site is fairly unique.

Bottom Line: The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat.Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces.Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave,, Cambridge, MA 02139 USA. jacopo@mit.edu.

ABSTRACT
Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement.

No MeSH data available.


Related in: MedlinePlus