通过搭建金属相变传热的综合实验系统，研究强磁场下金属镓的熔化过程，获得了磁场作用下金属镓的熔化换热特性。采用熔化过程中加热壁面与相界面的动态平均距离代替固定特征长度，以此研究熔化过程中对流换热与导热的相对强度随傅里叶数(Fo)的变化规律。结果表明：小哈特曼数(Ha)下，熔化前期具有促进熔化效果，后期则是抑制；大哈特曼数下磁场对金属镓的熔化过程中的对流具有抑制作用，熔化过程呈现层状均匀推进；磁场能够减小熔化过程中腔体底部导热主导区的高度并且抑制熔化过程中的温度波动，使熔化过程中的温度分布趋于均匀。
蔡志洋
,
孟旭
,
张登科
,
吴曦
,
王增辉
. 强磁场影响下金属相变传热的MHD效应实验研究[J]. 中国科学院大学学报, 2024
, 41(6)
: 746
-754
.
DOI: 10.7523/j.ucas.2023.021
As a highly efficient heat transport medium, the study of the melting and heat transfer characteristics of metallic fluids in phase change processes under magnetic fields is of great importance for industrial processes such as fusion reactors, electromagnetic metallurgy, and additive manufacturing. In this paper, the melting process of metallic gallium under a strong magnetic field was studied by building a comprehensive experimental system for heat transfer through phase change of metal, and the heat transfer characteristics of metallic gallium melting under the action of a magnetic field were obtained. The dynamic average distance of the heated wall from the phase interface during melting instead of the fixed characteristic length was used to study the variation of the relative strength of convective heat transfer and thermal conductivity with Fourier number (Fo) during melting. The results show that: under a small Hartmann number (Ha), the melting has a melting-promoting effect at the early stage and is inhibited at the later stage; under a large Hartmann number the magnetic field has an inhibiting effect on the convection during the melting of gallium metal, and the melting process shows a laminar and uniform advance. The magnetic field reduces the height of the dominant zone of thermal conductivity at the bottom of the cavity during the melting process and suppresses temperature fluctuations during the melting process, resulting in a uniform temperature distribution during the melting process.
[1] Stefan J. Ueber Die Theorie der Eisbildung, insbesondere über Die Eisbildung im Polarmeere[J]. Annalen Der Physik, 1891, 278(2): 269-286. DOI:10.1002/andp.18912780206.
[2] Shokouhmand H, Kamkari B. Experimental investigation on melting heat transfer characteristics of lauric acid in a rectangular thermal storage unit[J]. Experimental Thermal and Fluid Science, 2013, 50: 201-212. DOI:10.1016/j.expthermflusci.2013.06.010.
[3] Al Omari S A B, Ghazal A M, Elnajjar E, et al. Vibration-enhanced direct contact heat exchange using gallium as a solid phase change material[J]. International Communications in Heat and Mass Transfer, 2021, 120: 104990. DOI:10.1016/j.icheatmasstransfer.2020.104990.
[4] 颜晓虹, 胡学功, 赵耀华. 微槽群相变式微冷系统的换热特性实验[J]. 中国科学院研究生院学报, 2006, 23(3): 313-316. DOI:10.7523/j.issn.2095-6134.2006.3.005.
[5] Coenen J W, Philipps V, Brezinsek S, et al. Analysis of tungsten melt-layer motion and splashing under tokamak conditions at TEXTOR[J]. Nuclear Fusion, 2011, 51(8): 083008. DOI:10.1088/0029-5515/51/8/083008.
[6] Jany P, Bejan A. Scaling theory of melting with natural convection in an enclosure[J]. International Journal of Heat and Mass Transfer, 1988, 31(6): 1221-1235. DOI:10.1016/0017-9310(88)90065-8.
[7] Gau C, Viskanta R. Effect of natural convection on solidification from above and melting from below of a pure metal[J]. International Journal of Heat and Mass Transfer, 1985, 28(3): 573-587. DOI:10.1016/0017-9310(85)90180-2.
[8] Gau C, Viskanta R. Melting and solidification of a pure metal on a vertical wall[J]. Journal of Heat Transfer, 1986, 108(1): 174-181. DOI:10.1115/1.3246884.
[9] Kumar L, Manjunath B S, Patel R J, et al. Experimental investigations on melting of lead in a cuboid with constant heat flux boundary condition using thermal neutron radiography[J]. International Journal of Thermal Sciences, 2012, 61: 15-27. DOI:10.1016/j.ijthermalsci.2012.06.014.
[10] Zhang H, Charmchi M, Veilleux D, et al. Numerical and experimental investigation of melting in the presence of a magnetic field: simulation of low-gravity environment[J]. Journal of Heat Transfer, 2007, 129: 568-576. DOI:10.1115/1.2709961.
[11] Wang Z H, Meng X, Ni M J. Liquid metal buoyancy driven convection heat transfer in a rectangular enclosure in the presence of a transverse magnetic field[J]. International Journal of Heat and Mass Transfer, 2017, 113: 514-523. DOI:10.1016/j.ijheatmasstransfer.2017.05.121.
[12] Okada K, Ozoe H. Experimental heat transfer rates of natural convection of molten Gallium suppressed under an external magnetic field in either the X, Y, or Z direction[J]. Journal of Heat Transfer, 1992, 114(1): 107-114. DOI:10.1115/1.2911234.
[13] Ghalambaz M, Doostanidezfuli A, Zargartalebi H, et al. MHD phase change heat transfer in an inclined enclosure: effect of a magnetic field and cavity inclination[J]. Numerical Heat Transfer, Part A: Applications, 2017, 71(1): 91-109. DOI:10.1080/10407782.2016.1244397.
[14] Feng Y C, Li H X, Li L X, et al. Investigation of the effect of magnetic field on melting of solid gallium in a bottom-heated rectangular cavity using the lattice Boltzmann method[J]. Numerical Heat Transfer, Part A: Applications, 2016, 69(11): 1263-1279. DOI:10.1080/10407782.2015. 1127732.
[15] Haddad Z, Iachachene F, Zidouni F, et al. Magnetic field effects on melting and solidification of PCMs in an isosceles triangular cavity[J]. Journal of Thermal Analysis and Calorimetry, 2022, 147(7): 4697-4709. DOI:10.1007/s10973-021-10857-5.
[16] Saha S K. Dynamics of phase change of gallium under magnetic field and thermocapillary effects under variable gravity conditions[J]. Thermal Science and Engineering Progress, 2022, 29: 101234. DOI:10.1016/j.tsep.2022.101234.
[17] Yamanaka Y, Kakimoto K, Ozoe H, et al. Rayleigh–Benard oscillatory natural convection of liquid gallium heated from below[J]. Chemical Engineering Journal, 1998, 71(3): 201-205. DOI:10.1016/S1385-8947(98)00100-4.
[18] 孙思睿, 张杰, 倪明玖. 横向磁场下侧壁加热方腔熔化的数值模拟研究[J]. 力学学报, 2022, 54(9): 2377-2386. DOI: 10.6052/0459-1879-22-155.
[19] Li M, Jiao Z J, Jia P. Melting processes of phase change materials in a horizontally placed rectangular cavity[J]. Journal of Fluid Mechanics, 2022, 950: A34. DOI:10.1017/jfm.2022.751.
[20] Okabe T, Miyanishi T, Miyagawa T, et al. Spatio-temporal measurement of natural convective heat transfer on melting process using infrared thermography[J]. International Journal of Heat and Mass Transfer, 2021, 181: 121882. DOI:10.1016/j.ijheatmasstransfer.2021.121882.
[21] Parsazadeh M, Malik M, Duan X L, et al. Numerical study on melting of phase change material in an enclosure subject to Neumann boundary condition in the presence of Rayleigh-Bénard convection[J]. International Journal of Heat and Mass Transfer, 2021, 171: 121103. DOI:10.1016/j.ijheatmasstransfer.2021.121103.
