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Enhancement of critical heat flux in nucleate boiling of nanofluids: a state-of-art review.

Kim H - Nanoscale Res Lett (2011)

Bottom Line: The purpose of this article is to provide an exhaustive review of these studies.Also, attempts to explain the physical mechanism based on available CHF theories are described.Finally, future research needs are identified.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nuclear Engineering, Kyung Hee University, Yongin, Gyunggi 446-701, Republic of Korea. hdkims@khu.ac.kr.

ABSTRACT
Nanofluids (suspensions of nanometer-sized particles in base fluids) have recently been shown to have nucleate boiling critical heat flux (CHF) far superior to that of the pure base fluid. Over the past decade, numerous experimental and analytical studies on the nucleate boiling CHF of nanofluids have been conducted. The purpose of this article is to provide an exhaustive review of these studies. The characteristics of CHF enhancement in nanofluids are systemically presented according to the effects of the primary boiling parameters. Research efforts to identify the effects of nanoparticles underlying irregular enhancement phenomena of CHF in nanofluids are then presented. Also, attempts to explain the physical mechanism based on available CHF theories are described. Finally, future research needs are identified.

No MeSH data available.


Related in: MedlinePlus

Experimental results of measured CHF values for both flat plates and thin wires. All are under atmospheric condition and with no additive.
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Figure 4: Experimental results of measured CHF values for both flat plates and thin wires. All are under atmospheric condition and with no additive.

Mentions: Nucleate boiling experiments for studying the CHF of nanofluids are normally conducted with thin wires or flat plates. Many previous studies used thin wires as a boiling surface to confirm an intriguing feature of nanofluids during nucleate boiling: significant CHF increase compared with a reference value for pure water. Thin wires were used to simplify the measurement of average heat flux and surface temperature and the post-inspection of the heater surface. However, the measured CHF values might be different from those obtained with the flat plates used in general applications. Figure 4 summarizes the experimental results for both flat plates and thin wires, all under atmospheric conditions and with no additive. A comparison of the CHF values for the two different heater geometries reveals that CHF enhancement is greater with thin wires (50 to approximately 200%) than with flat plates (30 to approximately 80%). This difference in the measured CHF values is due to the different CHF mechanisms with thin wires and large flat plates. Nucleate boiling with flat plates proceeds to film boiling via the hydrodynamic CHF mechanism, whereas CHF with thin wires is caused by the local dryout mechanism governed by boiling incipience phenomena, provided that hydrodynamic instabilities are absent [24].


Enhancement of critical heat flux in nucleate boiling of nanofluids: a state-of-art review.

Kim H - Nanoscale Res Lett (2011)

Experimental results of measured CHF values for both flat plates and thin wires. All are under atmospheric condition and with no additive.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211511&req=5

Figure 4: Experimental results of measured CHF values for both flat plates and thin wires. All are under atmospheric condition and with no additive.
Mentions: Nucleate boiling experiments for studying the CHF of nanofluids are normally conducted with thin wires or flat plates. Many previous studies used thin wires as a boiling surface to confirm an intriguing feature of nanofluids during nucleate boiling: significant CHF increase compared with a reference value for pure water. Thin wires were used to simplify the measurement of average heat flux and surface temperature and the post-inspection of the heater surface. However, the measured CHF values might be different from those obtained with the flat plates used in general applications. Figure 4 summarizes the experimental results for both flat plates and thin wires, all under atmospheric conditions and with no additive. A comparison of the CHF values for the two different heater geometries reveals that CHF enhancement is greater with thin wires (50 to approximately 200%) than with flat plates (30 to approximately 80%). This difference in the measured CHF values is due to the different CHF mechanisms with thin wires and large flat plates. Nucleate boiling with flat plates proceeds to film boiling via the hydrodynamic CHF mechanism, whereas CHF with thin wires is caused by the local dryout mechanism governed by boiling incipience phenomena, provided that hydrodynamic instabilities are absent [24].

Bottom Line: The purpose of this article is to provide an exhaustive review of these studies.Also, attempts to explain the physical mechanism based on available CHF theories are described.Finally, future research needs are identified.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nuclear Engineering, Kyung Hee University, Yongin, Gyunggi 446-701, Republic of Korea. hdkims@khu.ac.kr.

ABSTRACT
Nanofluids (suspensions of nanometer-sized particles in base fluids) have recently been shown to have nucleate boiling critical heat flux (CHF) far superior to that of the pure base fluid. Over the past decade, numerous experimental and analytical studies on the nucleate boiling CHF of nanofluids have been conducted. The purpose of this article is to provide an exhaustive review of these studies. The characteristics of CHF enhancement in nanofluids are systemically presented according to the effects of the primary boiling parameters. Research efforts to identify the effects of nanoparticles underlying irregular enhancement phenomena of CHF in nanofluids are then presented. Also, attempts to explain the physical mechanism based on available CHF theories are described. Finally, future research needs are identified.

No MeSH data available.


Related in: MedlinePlus