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Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe.

Park YS, Chang SH - Nanoscale Res Lett (2011)

Bottom Line: The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water.The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid.Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nuclear and Quantum Engineering, KAIST, 335 Gwahak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea. yusunpark@kaist.ac.kr.

ABSTRACT
A two-phase flow experiment using air and water-based γ-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water. The void fraction distribution was flattened in the nanofluid case more than it was in the pure water case. The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid. This was the first attempt to measure the local two-phase flow parameters of nanofluids using a conductivity double-sensor two-phase void meter. Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified. In addition, the heat transfer enhancement of the nanofluid can be resulted from the increase of the interfacial area concentration which means the available area of the heat and mass transfer.

No MeSH data available.


Related in: MedlinePlus

An overview of the experimental test loop.
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Figure 1: An overview of the experimental test loop.

Mentions: The overall test loop setup is shown in Figure 1. The setup consists of a tank in which the working fluid is stored, a pump circulating the working fluid at a variable speed, and the test section. There are six K-type thermocouples that measure the bulk temperatures of the working fluid. Measured temperatures were used to determine the fluid properties which were required to evaluate the experimental results. The measurement uncertainty of the thermocouples was estimated to be 2.2°C. The volume flow rate of the liquid is measured with a TOSHIBA LF400 flow meter (TOSHIBA Corporation, Tokyo, Japan) at an uncertainty level of about 0.1%. The air flow rate is controlled by an air Viton O-ring mass flow controller, (model M3030V; manufactured by Line Tech 400, Daejeon, Korea). The measurement error rate of the air flow meter is estimated to be less than 1%. The total volume of the test loop is about 288 L, and only 60 L of the working fluid is circulated in the test loop. The working fluids are water, air, and a water-based nanofluid; they are all used under atmospheric pressure.


Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe.

Park YS, Chang SH - Nanoscale Res Lett (2011)

An overview of the experimental test loop.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211349&req=5

Figure 1: An overview of the experimental test loop.
Mentions: The overall test loop setup is shown in Figure 1. The setup consists of a tank in which the working fluid is stored, a pump circulating the working fluid at a variable speed, and the test section. There are six K-type thermocouples that measure the bulk temperatures of the working fluid. Measured temperatures were used to determine the fluid properties which were required to evaluate the experimental results. The measurement uncertainty of the thermocouples was estimated to be 2.2°C. The volume flow rate of the liquid is measured with a TOSHIBA LF400 flow meter (TOSHIBA Corporation, Tokyo, Japan) at an uncertainty level of about 0.1%. The air flow rate is controlled by an air Viton O-ring mass flow controller, (model M3030V; manufactured by Line Tech 400, Daejeon, Korea). The measurement error rate of the air flow meter is estimated to be less than 1%. The total volume of the test loop is about 288 L, and only 60 L of the working fluid is circulated in the test loop. The working fluids are water, air, and a water-based nanofluid; they are all used under atmospheric pressure.

Bottom Line: The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water.The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid.Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nuclear and Quantum Engineering, KAIST, 335 Gwahak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea. yusunpark@kaist.ac.kr.

ABSTRACT
A two-phase flow experiment using air and water-based γ-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water. The void fraction distribution was flattened in the nanofluid case more than it was in the pure water case. The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid. This was the first attempt to measure the local two-phase flow parameters of nanofluids using a conductivity double-sensor two-phase void meter. Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified. In addition, the heat transfer enhancement of the nanofluid can be resulted from the increase of the interfacial area concentration which means the available area of the heat and mass transfer.

No MeSH data available.


Related in: MedlinePlus