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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.


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Pool boiling curve for DI water and nanofluids tests systematically discussed in this work. Approximate uncertainty in measurement of q" and ΔTs are both 2%. The ONB is at approximately the same superheat (~7°C) for all experiments (i.e., water and nanofluid ONB is very similar). ONB, onset of nucleate boiling.
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Figure 2: Pool boiling curve for DI water and nanofluids tests systematically discussed in this work. Approximate uncertainty in measurement of q" and ΔTs are both 2%. The ONB is at approximately the same superheat (~7°C) for all experiments (i.e., water and nanofluid ONB is very similar). ONB, onset of nucleate boiling.

Mentions: The nucleate boiling and critical heat flux characteristics of deionized water and water-based nanofluids were studied with infrared thermometry. Pool boiling curves (shown in Figure 2) were generated for the seven (three pure water and four nanofluid) experiments that are discussed in this paper by taking the time average (over 2.0 s) and space average (of a 5 × 5-mm2 area in the center of the heater) of the IR-measured temperature distribution at a given heat flux. Several generalized conclusions can be immediately inferred by inspecting this figure. First, the effective nucleate boiling heat transfer coefficient for all nanofluids is lower (i.e., deteriorated) compared with the water experiments since the boiling curves are shifted significantly to the right. This reduction is further highlighted in Figure 3; here, the heat transfer coefficient is calculated from knowledge of the heat flux, the average measured surface temperature, and the bulk fluid temperature (which is the saturation temperature for these experiments)(1)


Infrared thermometry study of nanofluid pool boiling phenomena.

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

Pool boiling curve for DI water and nanofluids tests systematically discussed in this work. Approximate uncertainty in measurement of q" and ΔTs are both 2%. The ONB is at approximately the same superheat (~7°C) for all experiments (i.e., water and nanofluid ONB is very similar). ONB, onset of nucleate boiling.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Pool boiling curve for DI water and nanofluids tests systematically discussed in this work. Approximate uncertainty in measurement of q" and ΔTs are both 2%. The ONB is at approximately the same superheat (~7°C) for all experiments (i.e., water and nanofluid ONB is very similar). ONB, onset of nucleate boiling.
Mentions: The nucleate boiling and critical heat flux characteristics of deionized water and water-based nanofluids were studied with infrared thermometry. Pool boiling curves (shown in Figure 2) were generated for the seven (three pure water and four nanofluid) experiments that are discussed in this paper by taking the time average (over 2.0 s) and space average (of a 5 × 5-mm2 area in the center of the heater) of the IR-measured temperature distribution at a given heat flux. Several generalized conclusions can be immediately inferred by inspecting this figure. First, the effective nucleate boiling heat transfer coefficient for all nanofluids is lower (i.e., deteriorated) compared with the water experiments since the boiling curves are shifted significantly to the right. This reduction is further highlighted in Figure 3; here, the heat transfer coefficient is calculated from knowledge of the heat flux, the average measured surface temperature, and the bulk fluid temperature (which is the saturation temperature for these experiments)(1)

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