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Investigation of Convective Heat Transfer Characteristics of Aqueous SiO2 Nanofluids under Laminar Flow Conditions

층류유동 조건에서 SiO2 나노유체의 대류 열전달 특성에 대한 연구

  • Park, Hyun-Ah (Metropolitan Transportation Research Center, Korea Railroad Research Institute) ;
  • Park, Ji-Hyun (Metropolitan Transportation Research Center, Korea Railroad Research Institute) ;
  • Jeong, Rag-Gyo (Metropolitan Transportation Research Center, Korea Railroad Research Institute) ;
  • Kang, Seok-Won (Metropolitan Transportation Research Center, Korea Railroad Research Institute)
  • 박현아 (한국철도기술연구원 광역도시교통연구본부) ;
  • 박지현 (한국철도기술연구원 광역도시교통연구본부) ;
  • 정락교 (한국철도기술연구원 광역도시교통연구본부) ;
  • 강석원 (한국철도기술연구원 광역도시교통연구본부)
  • Received : 2016.08.03
  • Accepted : 2016.09.09
  • Published : 2016.09.30

Abstract

The effect of the migration of nanoparticles near the wall of a channel on the convective heat transfer in a laminar flow of $SiO_2$ nanoparticle suspensions (nanofluids) under constant wall heat flux boundary conditions was numerically and experimentally investigated in this study. The dynamic thermal conductivity of the aqueous $SiO_2$ nanofluids was measured using T-type thermocouples attached to the outer surface of a stainless steel circular tube (with a length of 1 m and diameter of 1.75 mm). The nanofluids used in this study were synthesized by dispersing $SiO_2$ spherical nanoparticles with a diameter of 24 nm in de-ionized water (DIW). The enhancement of the thermal conductivity of the nanofluids (e.g., an increase of up to 7.9 %) was demonstrated by comparing the temperature profiles in the flow of the nanofluids with that in the flow of the basefluids (i.e., DIW). However, this trend was not demonstrated in the computational analysis, because the numerical models were based on continuum assumptions and flow features involving nanoparticles in a stable colloidal solution. Thus, to explore the non-continuum effects, such as the modification of the morphology caused by nanoparticle-wall interactions on the heat exchanging surfaces (e.g., the isolated and dispersed precipitation of the nanoparticles), additional experiments were performed using DIW right after the measurements using the nanofluids.

본 연구에서는 벽면으로부터 균일한 열 유속 조건에서 나노유체의 층류유동에 의한 대류 열전달 향상과 관련하여 유동관 내 벽면에서의 나노입자 거동의 영향에 대한 수치해석 및 실험 연구에 대해서 논한다. $SiO_2$ 나노유체의 동적 열전도도는 스테인리스 원형 관(길이 1 m 및 직경 1.75 mm)의 외면에 부착된 T형 열전대를 활용하여 측정하였다. 실험에 사용된 나노유체는 직경이 24 nm인 구형의 $SiO_2$ 나노 입자를 초순수에 분산시켜 제조하였다. 나노 유체의 향상된 열전도도(즉, 최대 7.9 %의 증가)는 기본유체(즉, 초순수)와 나노유체 간 유동에서 벽면 온도 변화를 측정하여 비교함으로써 확인하였다. 하지만, 수치해석 결과에서는 실험으로부터 발견된 경향이 발견되지 못했는데, 이는 수치해석 모델이 기본적으로 연속체역학 및 안정된 콜로이드 용액에 나노 입자를 포함하는 유동특성에 기반을 두기 때문으로 분석된다. 이에 따라, 열교환 표면에서 나노입자와 벽면 간 상호작용(예: 나노입자의 고립된 침전)에 의한 표면특성 변화와 같은 비연속체역학 기반의 효과를 확인하기 위하여, 나노유체의 흐름 직후 정제수를 활용한 추가실험을 수행하였다.

Keywords

References

  1. H. Masuda, A. Ebata, K. Teramae, N. Hishinuma, "Alteration of thermal conductivity and viscosity of liquid by dispersing ultra-fine particles (Dispersion of ${\gamma}$ -$TiO_2$, TEX>$SiO_2$ and $TiO_2$ ultra-fine particles)", Netsu Bussei, vol. 7, pp. 227-233, 1993. DOI: http://dx.doi.org/10.2963/jjtp.7.227
  2. S. Ozerinc, S. Kakac, A.G. Yazicioglu, "Enhanced thermal conductivity of nanofluids: a state-of-the-art review", Microfluid. Nanofluid., vol. 8, pp. 145-170, 2010. DOI: http://dx.doi.org/10.1007/s10404-009-0524-4
  3. A. Vatani, P. L. Woodfield, D.V. Dao, "A Survey of practical equations for prediction of effective thermal conductivity of spherical-particle nanofluids", J. Mol. Liq., vol. 211, pp. 712-733, 2015. DOI: http://dx.doi.org/10.1016/j.molliq.2015.07.043
  4. L. Godson, B. Raja, D. Mohan Lal, S. Wongwises, "Enhancement of heat transfer using nanofluids-An overview", Renew. Sust. Energ. Rev., vol. 14, pp. 629-641, 2010. DOI: http://dx.doi.org/10.1016/j.rser.2009.10.004
  5. J. T. Kwon, T. H. Nahm, T. W. Kim, Y.C. Kwon, "An Experimental Study on Pressure Drop and Heat Transfer Coefficient of Laminar Ag Nanofluid flow in Mini Tubes", Journal of the Korea Academia-Industrial cooperation Society, vol. 10, pp. 3525-3532, 2009. https://doi.org/10.5762/KAIS.2009.10.12.3525
  6. Y. G. Kim, S. H. Jo, Y. J. Seong, H. S. Chung, H.M. Jeong, "Experimental investigation of heat transfer characteristics of alumina nanofluid", Journal of the Korean Society of Marine Engineering, vol. 37, pp. 16-21, 2013. DOI: http://dx.doi.org/10.5916/jkosme.2013.37.1.16
  7. L. Yu-Hua, Q. Wei, F. Jian-Chao, F., "Temperature Dependence of Thermal Conductivity of Nanofluids", Chinese. Phys. Lett., vol. 25, pp. 3319-3322, 2008. DOI: http://dx.doi.org/10.1088/0256-307X/25/9/060
  8. C.H. Li, G.P. Peterson, "Experimental investigation of temperature and volume fraction variations on the effective thermal conductivity of nanoparticle suspensions (nanofluids)," J. Appl. Phys., vol. 99, pp. 084314, 2006. DOI: http://dx.doi.org/10.1063/1.2191571
  9. M. Chopkar, S. Sudarshan, P.K. Das, I. Manna, "Effect of particle size on thermal conductivity of nanofluid", Metall. Mater. Trans. A, vol. 39, pp.1535-1542, 2008. DOI: http://dx.doi.org/10.1007/s11661-007-9444-7
  10. H. Xie, J. Wang, T. Xi, Y. Liu, "Thermal Conductivity of Suspensions Containing Nanosized SiC Particles," Int. J. Thermophys., vol. 23, pp.571-580, 2002. DOI: http://dx.doi.org/10.1023/A:1015121805842
  11. Y.S. Na, K.D. Kihm, J.S. Lee, "ReD-dependence of Dynamic Thermal Conductivities of Nanofluids," Int. J. Heat Mass Tran., vol. 55, pp. 7933-7940, 2012. DOI: http://dx.doi.org/10.1016/j.ijheatmasstransfer.2012.08.026
  12. S.J. Kline, F.A. McClintock, "Describing uncertainties in single sample experiments", Mechanical Engineering, vol. 75, pp. 3-8, 1953.
  13. S.M.S. Murshed, K.C. Leong, C. Yang, "Investigations of thermal conductivity and viscosity of nanofluids", Int. J. Therm. Sci., vol. 47, pp. 560-568, 2008. DOI: http://dx.doi.org/10.1016/j.ijthermalsci.2007.05.004
  14. C. Kleinstreuer, Y. Feng, "Thermal nanofluid property model with application to nanofluid flow in a parallel-disk system-Part I: A new thermal conductivity model for nanofluid flow", J. Heat Transf., vol. 134, pp. 051002, 2012. DOI: http://dx.doi.org/10.1115/1.4005632
  15. G.S. McNab, A. Meisen, "Thermophoresis in Liquids" J. Colloid Interf. Sci., vol. 44, pp. 339-346, 1973. DOI: http://dx.doi.org/10.1016/0021-9797(73)90225-7