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Round-robin test on thermal conductivity measurement of ZnO nanofluids and comparison of experimental results with theoretical bounds.

Lee WH, Rhee CK, Koo J, Lee J, Jang SP, Choi SU, Lee KW, Bae HY, Lee GJ, Kim CK, Hong SW, Kwon Y, Kim D, Kim SH, Hwang KS, Kim HJ, Ha HJ, Lee SH, Choi CJ, Lee JH - Nanoscale Res Lett (2011)

Bottom Line: Ethylene glycol (EG)-based zinc oxide (ZnO) nanofluids containing no surfactant have been manufactured by one-step pulsed wire evaporation (PWE) method.Round-robin tests on thermal conductivity measurements of three samples of EG-based ZnO nanofluids have been conducted by five participating labs, four using accurate measurement apparatuses developed in house and one using a commercial device.The results have been compared with several theoretical bounds on the effective thermal conductivity of heterogeneous systems.

View Article: PubMed Central - HTML - PubMed

Affiliation: Mechanical and Industrial Engineering Department, University of Illinois at Chicago, Chicago, IL, USA. suschoi@uic.edu.

ABSTRACT
Ethylene glycol (EG)-based zinc oxide (ZnO) nanofluids containing no surfactant have been manufactured by one-step pulsed wire evaporation (PWE) method. Round-robin tests on thermal conductivity measurements of three samples of EG-based ZnO nanofluids have been conducted by five participating labs, four using accurate measurement apparatuses developed in house and one using a commercial device. The results have been compared with several theoretical bounds on the effective thermal conductivity of heterogeneous systems. This study convincingly demonstrates that the large enhancements in the thermal conductivities of EG-based ZnO nanofluids tested are beyond the lower and upper bounds calculated using the models of the Maxwell and Nan et al. with and without the interfacial thermal resistance.

No MeSH data available.


Schematic diagram and photographs of PWE system and subsystems. (a) Schematic diagram of PWE system. (b) Photograph of PWE subsystems.
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Figure 1: Schematic diagram and photographs of PWE system and subsystems. (a) Schematic diagram of PWE system. (b) Photograph of PWE subsystems.

Mentions: As shown in Figure 1, the PWE system for synthesis of EG-based ZnO nanofluids consists of three main components which are the pulsed power generator, the control panel, and the evaporation chamber with continuous wire feeding and fluid nozzle subsystems. Pure Zn wire of 99.9% with a diameter of 0.5 mm was used as a starting material and the feeding length of the wire into the reaction chamber was 100 mm. When a pulsed high voltage of 25 kV is driven through a thin wire, non-equilibrium overheating induced in the wire makes the wire evaporate into plasma within several microseconds. Then the high-temperature plasma is cooled by an interaction with an argon-oxygen mixed gas, and evaporated Zn gas is condensed into small-sized particles and spontaneously immersed into EG-stained chamber. The Ar:O2 atmosphere in the evaporation chamber facilitates formation of the zinc oxide phase. More details of the PWE method and system are given in [45].


Round-robin test on thermal conductivity measurement of ZnO nanofluids and comparison of experimental results with theoretical bounds.

Lee WH, Rhee CK, Koo J, Lee J, Jang SP, Choi SU, Lee KW, Bae HY, Lee GJ, Kim CK, Hong SW, Kwon Y, Kim D, Kim SH, Hwang KS, Kim HJ, Ha HJ, Lee SH, Choi CJ, Lee JH - Nanoscale Res Lett (2011)

Schematic diagram and photographs of PWE system and subsystems. (a) Schematic diagram of PWE system. (b) Photograph of PWE subsystems.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211320&req=5

Figure 1: Schematic diagram and photographs of PWE system and subsystems. (a) Schematic diagram of PWE system. (b) Photograph of PWE subsystems.
Mentions: As shown in Figure 1, the PWE system for synthesis of EG-based ZnO nanofluids consists of three main components which are the pulsed power generator, the control panel, and the evaporation chamber with continuous wire feeding and fluid nozzle subsystems. Pure Zn wire of 99.9% with a diameter of 0.5 mm was used as a starting material and the feeding length of the wire into the reaction chamber was 100 mm. When a pulsed high voltage of 25 kV is driven through a thin wire, non-equilibrium overheating induced in the wire makes the wire evaporate into plasma within several microseconds. Then the high-temperature plasma is cooled by an interaction with an argon-oxygen mixed gas, and evaporated Zn gas is condensed into small-sized particles and spontaneously immersed into EG-stained chamber. The Ar:O2 atmosphere in the evaporation chamber facilitates formation of the zinc oxide phase. More details of the PWE method and system are given in [45].

Bottom Line: Ethylene glycol (EG)-based zinc oxide (ZnO) nanofluids containing no surfactant have been manufactured by one-step pulsed wire evaporation (PWE) method.Round-robin tests on thermal conductivity measurements of three samples of EG-based ZnO nanofluids have been conducted by five participating labs, four using accurate measurement apparatuses developed in house and one using a commercial device.The results have been compared with several theoretical bounds on the effective thermal conductivity of heterogeneous systems.

View Article: PubMed Central - HTML - PubMed

Affiliation: Mechanical and Industrial Engineering Department, University of Illinois at Chicago, Chicago, IL, USA. suschoi@uic.edu.

ABSTRACT
Ethylene glycol (EG)-based zinc oxide (ZnO) nanofluids containing no surfactant have been manufactured by one-step pulsed wire evaporation (PWE) method. Round-robin tests on thermal conductivity measurements of three samples of EG-based ZnO nanofluids have been conducted by five participating labs, four using accurate measurement apparatuses developed in house and one using a commercial device. The results have been compared with several theoretical bounds on the effective thermal conductivity of heterogeneous systems. This study convincingly demonstrates that the large enhancements in the thermal conductivities of EG-based ZnO nanofluids tested are beyond the lower and upper bounds calculated using the models of the Maxwell and Nan et al. with and without the interfacial thermal resistance.

No MeSH data available.