Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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Measuring Convective Heat Transfer Coefficient of Nanofluids Considering Effect of Film Temperature Change over Heated Fine Wire

막온도 변화를 고려한 가는 열선주위 나노유체의 대류열전달계수 측정 실험

  • Lee, Shinpyo (Dept. of Mechanical Engineering, Kyonggi Univ.)
  • 이신표 (경기대학교 기계시스템공학과)
  • Received : 2012.12.09
  • Accepted : 2013.07.08
  • Published : 2013.08.01
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Abstract

This study examined the convective heat transfer characteristics of nanofluids flowing over a heated fine wire. Convective heat transfer coefficients were measured for four different nano-engine-oil samples under three different temperature boundary conditions, i.e., both or either variation of wire and fluid temperature and constant film temperature. Experimental investigations that the increase in the convective heat transfer coefficients of nanofluids in the internal pipe flow often exceeded the increase in thermal conductivity were recently published; however, the current study did not confirm these results. Analyzing the behavior of the convective heat transfer coefficient under various temperature conditions was a useful tool to explain the relation between the thermal conductivity and the boundary layer thickness of nanofluids.

본 논문에서는 가는 열선 주위를 흐르는 나노유체의 대류열전달 특성을 실험을 통하여 검토하였다. 입자 혼합 농도가 다른 4개의 나노엔진오일에 대하여 열선온도가 증가하는 경우, 유체온도가 증가하는 경우 그리고 막온도가 일정하게 유지되는 경우 등 세가지 온도경계조건에 대하여 대류열전달계수를 측정하였다. 내부유동에서 나노유체의 대류열전달계수 상승이 열전도율 상승을 초과한다는 결과가 최근 발표되기도 했지만 본 연구에서는 이 결과를 확인할 수 없었다. 온도조건에 따른 대류열전달계수의 변화 거동을 분석함으로써 나노유체의 열전도율과 경계층두께의 관계를 설명할 수 있었다.

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References

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