Limits...
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

Lift coefficient in terms of the mean bubble diameter.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211349&req=5

Figure 7: Lift coefficient in terms of the mean bubble diameter.

Mentions: The evaluation results of the lift force are shown in Figure 7. The negative lift coefficients of large bubbles in pure water indicate that the lift force is acting in a direction of the center of the test section. Some large bubbles in the pure water are forced to the center of the test section, and some small bubbles in the pure water are forced to the inner wall of the test section; together they form a void fraction distribution with a center-peaked shape. However, in the nanofluid case, the lift coefficient is always positive, which means that the force acting on the bubbles is in the direction of the inner wall of the test section. Thus, smaller bubbles in the nanofluid shift from the center to the wall, and the void fraction distribution in this case becomes flatter than that of the pure water case.


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

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

Lift coefficient in terms of the mean bubble diameter.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Lift coefficient in terms of the mean bubble diameter.
Mentions: The evaluation results of the lift force are shown in Figure 7. The negative lift coefficients of large bubbles in pure water indicate that the lift force is acting in a direction of the center of the test section. Some large bubbles in the pure water are forced to the center of the test section, and some small bubbles in the pure water are forced to the inner wall of the test section; together they form a void fraction distribution with a center-peaked shape. However, in the nanofluid case, the lift coefficient is always positive, which means that the force acting on the bubbles is in the direction of the inner wall of the test section. Thus, smaller bubbles in the nanofluid shift from the center to the wall, and the void fraction distribution in this case becomes flatter than that of the pure water case.

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