低体积分数水基SiO_2纳米流体沸腾换热关键物性参数研究
|
摘要
在不添加任何分散剂和改变pH值的情况下,通过两步法将比表面积为150 m~2/g的气相SiO_2纳米颗粒制备成均匀稳定、透明度高、分散性能好的纳米流体。并对该功能性纳米流体进行了导热系数、黏度、表面张力和壁面接触角的测量。低体积分数下,功能性纳米流体较基液的导热系数几乎没有变化,但黏度却有较大改变。传统固液两相混合物黏度模型不再适用功能性纳米流体的计算,其主要原因是传统公式低估了分子间作用力对纳米流体黏度的影响。因此,建立了功能性纳米流体的黏度经验公式。由于纳米颗粒的存在提高了沸腾表面的粗糙度,从而使纳米流体的壁面湿润性能大大提高。实验结果表明,纳米流体的黏性和壁面接触角是沸腾换热发生骤变的关键。
Functional nanofluids are prepared by two-step process. It is can be prepared without any dispersant and the change of pH value. Functional nanofluids refer to SiO_2-water nanofluids with a specific surface area of 150 m~2/g and silica nanoparticles prepared by CVD. The nanofluid have uniform, stability, high transparency and good dispersion performance. And the thermal conductivity, viscosity, surface tension and solid-liquid contact angle of the functional nanofluids were also measured. At low concentration, nanoparticles in the fluid has little effect on thermal conductivity, but viscosity are greatly changed. The traditional solid-liquid two-phase mixture viscosity model is no longer suitable for the calculation of functional nanofluids. The main reason is that traditional formulas underestimate the influence of intermolecular forces on the viscosity of nanofluids. Therefore, the empirical formula for the viscosity of functional nanofluids is established. Compared to the pure water, the nanofluid can significantly increase the wettability of the wall surface is that the nanoparticles increase the roughness of the heated surface. Thereby, it is greatly improving the wettability of the nanofluid. The experimental results show that viscosity and wall contact angle of nanofluids are the key to sudden changes in boiling heat transfer.
Functional nanofluids are prepared by two-step process. It is can be prepared without any dispersant and the change of pH value. Functional nanofluids refer to SiO_2-water nanofluids with a specific surface area of 150 m~2/g and silica nanoparticles prepared by CVD. The nanofluid have uniform, stability, high transparency and good dispersion performance. And the thermal conductivity, viscosity, surface tension and solid-liquid contact angle of the functional nanofluids were also measured. At low concentration, nanoparticles in the fluid has little effect on thermal conductivity, but viscosity are greatly changed. The traditional solid-liquid two-phase mixture viscosity model is no longer suitable for the calculation of functional nanofluids. The main reason is that traditional formulas underestimate the influence of intermolecular forces on the viscosity of nanofluids. Therefore, the empirical formula for the viscosity of functional nanofluids is established. Compared to the pure water, the nanofluid can significantly increase the wettability of the wall surface is that the nanoparticles increase the roughness of the heated surface. Thereby, it is greatly improving the wettability of the nanofluid. The experimental results show that viscosity and wall contact angle of nanofluids are the key to sudden changes in boiling heat transfer.
引文
[1] CHOI S U S, EASTMAN J A. Enhancing thermal conductivity of fluids with nanoparticles [C] // ASME International Mechanical Engineering Congress & Exposition, November 12-17, 1995, San Francisco, CA. New York: ASME, 1995:99-103.
[2] 薛淑文,李雨晴,肖卓楠,等. 水基SiO2纳米流体沸腾换热特性 [J]. 化工学报, 2017, 68(11):4147-4153. XUE Shu-wen, LI Yu-qing, XIAO Zhuo-nan, et al. Boiling heat transfer characteristics of water-based SiO2 nanofluids [J]. CIESC Journal, 2017, 68(11):4147-1453. (in Chinese)
[3] PUTNAM S A, CAHILL D G, BRAUN P V, et al. Thermal conductivity of nanoparticle suspensions [J]. Journal of Applied Physics, 2006, 99(6):084308.
[4] ZHANG X, GU H, FU J M. Experimental study on the effective thermal conductivity and thermal diffusivity of nanofluids [J]. International Journal of Thermophysics, 2006, 27:569-580.
[5] ZHANG X, GU H, FU J M. Effective thermal conductivity and thermal diffusivity of nanofluids containing spherical and cylindrical nanoparticles [J]. Journal of Applied Physics, 2007, 31(6):593-599.
[6] EAPEN J, WILLIAMS W C, BUONGIORNO J, et al. Mean-field versus microconvection effects in nanfluid thermal conduction [J]. Physical Review Letters, 2007, 99(4):095901.
[7] TIMOFEEVA E V, GAVRILOV A N, Mc CLOSKEY J M, et al. Thermal conductivity and particle agglomeration in alumina nanofluids: Experiment and theory [J]. Physical Review: E, 2007, 76(16):061203.
[8] BUONGIORNO J, VENERUS D C, PRABHAT N, et al. A benchmark study on the thermal conductivity of nanofluids [J]. Journal of Applied Physics, 2009, 106(14):094312.
[9] TEGA A S, BECK M P, YUN H, et al. The limiting behavior of the thermal conductivity of nanoparticles and nanofluids [J]. Journal of Applied Physics, 2010, 107(4):114319.
[10] LEE S, CHOI S U S, LI S, et al. Measuring thermal conductivity of fluids containing oxide nanoparticles [J]. Journal of Heat Transfer, 1999, 121(2):280-289.
[11] MASUDA H, EBATA A, TERAMAE K, et al. Alternation of thermal conductivity and viscosity of liquid by dispersing ultra-fine particles [J]. Netsu Bussei, 1993, 4(4):227-233.
[12] 吴利民,段先健,杨本意,等. 气相二氧化硅的制备方法及其特性 [J]. 有机硅氟资讯, 2004, 6:24-26.
[13] MAXWELL J C. A Treatise on Electricity and Magnetism [M]. 2nd ed. Cambridge: Clarendon Press, 1881.
[14] RAYLEIGH L. On the influence of obstacles arranged in rectangular order upon the properties of a medium [J]. Philosophical Magazine, 1892, 34:481-507.
[15] DAVIS R H. The effective thermal conductivity of a composite material with spherical inclusions [J]. International Journal of Thermo - Physics, 1986, 7(3):609-620.
[16] LU S, LIN H. Effective conductivity of composites containing aligned spherical inclusions of finite conductivity [J]. Journal of Applied Physics, 1996, 79(9):6761-6769.
[17] EINSTEIN A. Eine neue bestimmung der moleküldimensionen [J]. Annalen der Physik, 1906, 324(2):289-306.
[18] BRINKMAN H. The viscosity of concentrated suspensions and solutions [J]. Journal of Chemical Physics, 1952, 20:571.
[19] BATCHELOR G. The effect of Brownian motion on the bulk stress in a suspension of spherical particles [J]. Journal of Fluid Mechanics, 1977, 83(1):97-117.
[20] NGUYEN C, DESGRANGES F, ROY G, et al. Temperature and particle-size dependent viscosity data for water-based nanofluids-hysteresis phenomenon [J]. International Journal of Heat and Fluid Flow, 2007, 28(6):1492-1506.
[21] LI X D, LI K, TU J Y, et al. On two-fluid modeling of nucleate boiling of dilute nanofluids [J]. International Journal of Heat and Mass Transfer, 2014, 69(2):443-450.
[22] LI K, LI X D, TU J Y, et al. A mathematic model considering the effect of Brownian motion for subcooled nucleate pool boiling of dilute nanofluids [J]. International Journal of Heat and Mass Transfer, 2015, 84:46-53.
[23] 李科,薛淑文,李义科. 一个水基SiO2纳米流体核态池沸腾数学模型 [J]. 热科学与技术, 2017, 16(1):1-7. LI Ke, XUE Shu-wen, LI Yi-ke. Mathematic model of nucleate pool boiling of SiO2-water nanofluid [J]. Journal of Thermal Science and Technology, 2017, 16(1):1-7. (in Chinese)
[24] BUONGIORNO J, HU L W, APOSTOLAKIS G, et al. A feasibility assessment of the use of nanofluids to enhance the in-vessel retention capability in light-water reactors [J]. Nuclear Engineering and Design, 2009, 239:941-948.
[25] YOUNG T. An essay on the cohesion of fluids philos [J]. A Philosophical Transactions of the Royal Society of London, 1805, 95:65-87.
[26] WENZEL R N. Resistance of solid surfaces to wetting by water [J]. Industrial and Engineering Chemistry Research, 1936, 28:988-994.
[2] 薛淑文,李雨晴,肖卓楠,等. 水基SiO2纳米流体沸腾换热特性 [J]. 化工学报, 2017, 68(11):4147-4153. XUE Shu-wen, LI Yu-qing, XIAO Zhuo-nan, et al. Boiling heat transfer characteristics of water-based SiO2 nanofluids [J]. CIESC Journal, 2017, 68(11):4147-1453. (in Chinese)
[3] PUTNAM S A, CAHILL D G, BRAUN P V, et al. Thermal conductivity of nanoparticle suspensions [J]. Journal of Applied Physics, 2006, 99(6):084308.
[4] ZHANG X, GU H, FU J M. Experimental study on the effective thermal conductivity and thermal diffusivity of nanofluids [J]. International Journal of Thermophysics, 2006, 27:569-580.
[5] ZHANG X, GU H, FU J M. Effective thermal conductivity and thermal diffusivity of nanofluids containing spherical and cylindrical nanoparticles [J]. Journal of Applied Physics, 2007, 31(6):593-599.
[6] EAPEN J, WILLIAMS W C, BUONGIORNO J, et al. Mean-field versus microconvection effects in nanfluid thermal conduction [J]. Physical Review Letters, 2007, 99(4):095901.
[7] TIMOFEEVA E V, GAVRILOV A N, Mc CLOSKEY J M, et al. Thermal conductivity and particle agglomeration in alumina nanofluids: Experiment and theory [J]. Physical Review: E, 2007, 76(16):061203.
[8] BUONGIORNO J, VENERUS D C, PRABHAT N, et al. A benchmark study on the thermal conductivity of nanofluids [J]. Journal of Applied Physics, 2009, 106(14):094312.
[9] TEGA A S, BECK M P, YUN H, et al. The limiting behavior of the thermal conductivity of nanoparticles and nanofluids [J]. Journal of Applied Physics, 2010, 107(4):114319.
[10] LEE S, CHOI S U S, LI S, et al. Measuring thermal conductivity of fluids containing oxide nanoparticles [J]. Journal of Heat Transfer, 1999, 121(2):280-289.
[11] MASUDA H, EBATA A, TERAMAE K, et al. Alternation of thermal conductivity and viscosity of liquid by dispersing ultra-fine particles [J]. Netsu Bussei, 1993, 4(4):227-233.
[12] 吴利民,段先健,杨本意,等. 气相二氧化硅的制备方法及其特性 [J]. 有机硅氟资讯, 2004, 6:24-26.
[13] MAXWELL J C. A Treatise on Electricity and Magnetism [M]. 2nd ed. Cambridge: Clarendon Press, 1881.
[14] RAYLEIGH L. On the influence of obstacles arranged in rectangular order upon the properties of a medium [J]. Philosophical Magazine, 1892, 34:481-507.
[15] DAVIS R H. The effective thermal conductivity of a composite material with spherical inclusions [J]. International Journal of Thermo - Physics, 1986, 7(3):609-620.
[16] LU S, LIN H. Effective conductivity of composites containing aligned spherical inclusions of finite conductivity [J]. Journal of Applied Physics, 1996, 79(9):6761-6769.
[17] EINSTEIN A. Eine neue bestimmung der moleküldimensionen [J]. Annalen der Physik, 1906, 324(2):289-306.
[18] BRINKMAN H. The viscosity of concentrated suspensions and solutions [J]. Journal of Chemical Physics, 1952, 20:571.
[19] BATCHELOR G. The effect of Brownian motion on the bulk stress in a suspension of spherical particles [J]. Journal of Fluid Mechanics, 1977, 83(1):97-117.
[20] NGUYEN C, DESGRANGES F, ROY G, et al. Temperature and particle-size dependent viscosity data for water-based nanofluids-hysteresis phenomenon [J]. International Journal of Heat and Fluid Flow, 2007, 28(6):1492-1506.
[21] LI X D, LI K, TU J Y, et al. On two-fluid modeling of nucleate boiling of dilute nanofluids [J]. International Journal of Heat and Mass Transfer, 2014, 69(2):443-450.
[22] LI K, LI X D, TU J Y, et al. A mathematic model considering the effect of Brownian motion for subcooled nucleate pool boiling of dilute nanofluids [J]. International Journal of Heat and Mass Transfer, 2015, 84:46-53.
[23] 李科,薛淑文,李义科. 一个水基SiO2纳米流体核态池沸腾数学模型 [J]. 热科学与技术, 2017, 16(1):1-7. LI Ke, XUE Shu-wen, LI Yi-ke. Mathematic model of nucleate pool boiling of SiO2-water nanofluid [J]. Journal of Thermal Science and Technology, 2017, 16(1):1-7. (in Chinese)
[24] BUONGIORNO J, HU L W, APOSTOLAKIS G, et al. A feasibility assessment of the use of nanofluids to enhance the in-vessel retention capability in light-water reactors [J]. Nuclear Engineering and Design, 2009, 239:941-948.
[25] YOUNG T. An essay on the cohesion of fluids philos [J]. A Philosophical Transactions of the Royal Society of London, 1805, 95:65-87.
[26] WENZEL R N. Resistance of solid surfaces to wetting by water [J]. Industrial and Engineering Chemistry Research, 1936, 28:988-994.