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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 cycle time distributions for a single DI water nucleation site (Expt. 2, q"= 50 kW/m2). Shown are the (a) temperature history and distributions of the (b) cycle time, (c) growth time, and (d) ratio of growth to cycle time.
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Figure 14: Bubble cycle time distributions for a single DI water nucleation site (Expt. 2, q"= 50 kW/m2). Shown are the (a) temperature history and distributions of the (b) cycle time, (c) growth time, and (d) ratio of growth to cycle time.

Mentions: Data from many bubble cycles at each nucleation site are used to arrive at the average values for the departure frequency, growth time, and wait time that are used in the heat transfer coefficient and CHF models discussed in "Data interpretation." There is, of course, some variability in these parameters even for a given nucleation site. In order to provide an example of this variability, a single nucleation site for DI water (Expt. 2, q" = 50 kW/m2) is chosen. For this nucleation site, a 1.0-s temperature history along with the distribution of the cycle time, tcycle (1/fb), growth time, tg, and growth-to-cycle time ratio are shown in Figure 14. Other nucleation sites, fluids, and heat fluxes have distributions that are correspondingly narrow.


Infrared thermometry study of nanofluid pool boiling phenomena.

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

Bubble cycle time distributions for a single DI water nucleation site (Expt. 2, q"= 50 kW/m2). Shown are the (a) temperature history and distributions of the (b) cycle time, (c) growth time, and (d) ratio of growth to cycle time.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 14: Bubble cycle time distributions for a single DI water nucleation site (Expt. 2, q"= 50 kW/m2). Shown are the (a) temperature history and distributions of the (b) cycle time, (c) growth time, and (d) ratio of growth to cycle time.
Mentions: Data from many bubble cycles at each nucleation site are used to arrive at the average values for the departure frequency, growth time, and wait time that are used in the heat transfer coefficient and CHF models discussed in "Data interpretation." There is, of course, some variability in these parameters even for a given nucleation site. In order to provide an example of this variability, a single nucleation site for DI water (Expt. 2, q" = 50 kW/m2) is chosen. For this nucleation site, a 1.0-s temperature history along with the distribution of the cycle time, tcycle (1/fb), growth time, tg, and growth-to-cycle time ratio are shown in Figure 14. Other nucleation sites, fluids, and heat fluxes have distributions that are correspondingly narrow.

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