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물 기반 탄소나노튜브 나노유체 히트파이프의 열적 특성에 관한 실험적 해석
하효준(Hyo Jun Ha),공유찬(Yu Chan Kong),도규형(Kyu Hyung Do),장석필(Seok Pil Jang) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.7
In this paper, thermal characteristics of cylindrical grooved wick heat pipes with water-based MWCNT nanofluids as working medium are experimentally investigated. Volume fractions of nanoparticles are varied with 0.1% to 0.5%. Transient hot wire method developed in house is used to measure the thermal conductivity of nanofluids. It is enhanced by up to 29% compared to that of DI water. The thermal resistances and temperature distributions at the surface of the heat pipes are measured at the same evaporation temperature. The experimental results show that the thermal resistance of the heat pipes with water-based MWCNT nanofluids as working fluid is reduced up to 35.2% compared with that of heat pipe using DI water. The reduction rate of thermal resistance is greater than the enhancement rate of thermal conductivity. Finally, based on the experimental results, we present the reduction of the thermal resistances of the heat pipes compared with conventional heat pipes cannot be explained by only the thermal conductivity of water-based MWCNT nanofluids.
〈논문〉 Al₂O₃ 나노유체를 이용한 히트파이프의 열전달 성능에 관한 실험
김준호(Jun Ho Kim),황교식(Kyo Sik Hwang),공유찬(Yu Chan Kong),장석필(Seok Pil Jang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
In this paper, the thermal performance of heat pipes using water-based Al₂O₃ nanofluids as working fluids is experimentally presented. For the purpose, the heat pipes with the screen mesh wick are produced with copper tubes of outer diameter of 4㎜. Water-based Al₂O₃ nanofluids as working fluids ofthe heat pipes are manufactured by two-step method. The total length of the heat pipes is 300㎜, in which the evaporator section, the adiabatic section and the condenser section are 50㎜, 100㎜, and 150㎜, respectively. The overall thermal resistances of heat pipes using the nanofluids as working fluids are measured under the steady-state conditions. Based on the experimental results, it is shown that the thermal resistance of the heat pipe is significant reduced as compared with that of a heat pipe with DI water.
1%미만의 부피비를 가지는 알루미나 나노유체의 유효 열전도도
이병호(Byeong Ho Lee),김준호(Jun Ho Kim),공유찬(Yu Chan Kong),장석필(Seok Pil Jang),구자예(Ja-Ye Koo) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
In this paper, effective thermal conductivities of water-based Al₂O₃-nanofluids with low concentration from 0.01 vol. % to 0.3 vol. % are experimentally obtained by transient hot wire method (THWM). The water-based Al₂O₃-nanofluids are manufactured by two-step method which is widely used. To examine suspension and dispersion characteristics of the water-based Al₂O₃-nanofluids, Zeta potential as well as transmission electron micrograph (TEM) is observed. We confirm the manufactured Al₂O₃-nanofluids have good suspension and dispersion. The effective thermal conductivities of the water-based Al₂O₃-nanofluids with low concentration are enhanced up to 1.64% compared with that of DI water at 21℃. In addition, experimental results are compared with theoretical results from Jang and Choi model.