Constrained melting heat transfer of composite phase change materials inside spherical container
LIU Min jie1, ZHU Zi qin1, XU Can ling1, FAN Li wu1, LU Hai1,2, YU Zi tao1,3
1. Institute of Thermal Science and Power Systems, Zhejiang University, Hangzhou 310027, China;2. Electric Power Research Institute, Yunnan Electric Power and Research Institute (Group), Kunming 650217, China；3.Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Hangzhou 310027, China
The constrained melting heat transfer of dodecanol based composite phase change materials (PCM) with addition of graphite nanoplatelets inside a spherical container, as a typical shape, was analyzed quantitatively by experiments in order to examine the influence of highly conductive fillers on melting heat transfer of composite PCM. By adopting the transient melt fraction by mass during melting as a means for comparison, a parametric study was conducted on the mass fraction of graphite nanoplatelets as well as the isothermal heating boundary condition. Results show that the melting heat transfer of the composite PCM experiences a transition from convection dominated to conduction dominated with the mass fraction increasing. And within the studied cases, although the thermal conductivity of the composite PCM is enhanced to some extent, such enhancement is not sufficient to compensate the loss of natural convection due to the increased viscosity but to slow down the melting process. An experimental correlation for the melt fraction was proposed in terms of the characteristic dimensionless groupings, such as the Fourier, Stefan and Grashof numbers, with predictive deviation less than 15%．
LIU Min jie, ZHU Zi qin, XU Can ling, FAN Li wu, LU Hai, YU Zi tao. Constrained melting heat transfer of composite phase change materials inside spherical container. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2016, 50(3): 477-484.
［1］ ZALBA B, MARIN J M, CABEZA L F, et al. Review on thermal energy storage with phase change: materials, heat transfer analysis and applications ［J］. Applied Thermal Engineering, 2003, 23(3): 251283．
［2］ DHAIDAN N D, KHODADADI J M. Melting and convection of phase change materials in different shape containers: a review ［J］. Renewable and Sustainable Energy Reviews, 2015, 43: 449477．
［3］ SAITOH T. Optimum design for latent heat thermal energy storage reservoir ［J］. Refrigeration, 1983, 58(670): 749756．
［4］ BILIR L, ILKEN Z. Total solidification time of a liquid phase change material enclosed in cylindrical/spherical container ［J］. Applied Thermal Engineering, 2005, 25(10): 14881502．
［5］ ARCHIBOLD A R, GONZALEZ AGUILAR J, RAHMAN M M, et al. The melting process of storage materials with relatively high phase change temperatures in partially filled spherical shells ［J］. Applied Energy, 2014, 116: 243252．
［6］ RIZAN M Z M, TAN F L, TSO C P. An experimental study of n octadecane melting inside a sphere subjected to constant heat rate at surface ［J］.International Communications in Heat and Mass Transfer, 2012, 39(10): 16241630．
［7］ TAN F L. Constrained and unconstrained melting inside a sphere ［J］. International Communications in Heat and Mass Transfer, 2008, 35(4): 466475．
［8］ HOSSEINIZADEH S F, DARZI A A, TAN F L, et al. Unconstrained melting inside a sphere ［J］. International Journal Thermal Sciences, 2013, 63: 5564．
［9］ ASSIS E, KATSMAN L, ZISKIND G, et al. Numerical and experimental study of melting in a spherical shell ［J］. International Journal of Heat and Mass Transfer, 2007, 50(9/10): 17901804．
［10］ KHODADADI J M, ZHANG Y. Effects of buoyancy driven convection on melting within spherical containers ［J］. International Journal of Heat and Mass Transfer, 2001, 44(8): 16051618．
［11］ TAN F L, HOSSEINIZADEH S F, KHODADADI J M, et al. Experimental and computational study of constrained melting of phase change materials (PCM) inside a spherical capsule ［J］. International Journal of Heat and Mass Transfer, 2009, 52(15/16): 34643472．
［12］ BARBA A, SPRIGA M. Discharge mode for encapsulated PCMs in storage tanks ［J］. Solar Energy, 2003, 74(2): 141148．
［13］ 朱子钦, 肖胜蓝, 施松鹤, 等. 相变材料在含翅片球形容器内的约束熔化传热过程［J］. 科学通报, 2015, 60(12): 11251131．
ZHU Zi qin, XIAO Sheng lan, SHI Song he, et al. Constrained melting heat transfer of a phase change material in a finned spherical capsule ［J］. Chinese Science Bulletin, 2015, 60(12): 11251131．
［14］ KOIZUMI H. Time and spatial heat transfer performance around an isothermally heated sphere placed in a uniform downwardly directed flow (in relation to the enhancement of latent heat storage rate in a spherical capsule) ［J］. Applied Thermal Engineering, 2004, 24(17/18): 25832600．
［15］ FAN L W, XIAO Y Q, ZENG Y. Effects of melting temperature and the presence of internal fins on the performance of a phase change material (PCM) based heat sink ［J］. International Journal of Thermal Sciences, 2013, 70: 114126．
［16］ FAN L, KHODADADI J M. Thermal conductivity enhancement of phase change materials for thermal energy storage: a review ［J］. Renewable and Sustainable Energy Reviews, 2011, 15(1): 2446．
［17］ KHODADADI J M, FAN L, BABAEI H. Thermal conductivity enhancement of nanostructure based colloidal suspensions utilized as phase change materials for thermal energy storage: a review ［J］. Renewable and Sustainable Energy Reviews, 2013, 24: 418444．
［18］ 王继芬,谢华清,辛忠,等.纳米ZnO/石蜡复合相变的热物理性质研究［J］.工程热物理学报,2011, 32,(11):18971899．
WANG Ji fen, XIE Hua qing, XIN Zhong, et al. Study on the thermophysical properties of paraffin wax composites containing ZnO nanopartides［J］.Journal of Engineering Thermophysics, 2011, 32(11):18971899．
［19］ HOSSEINIZADEH S F, DARZI A A, TAN F L. Numerical investigations of uncontrained melting of nano enhanced phase change material (NEPCM) inside a spherical container ［J］. International Journal of Thermal Science, 2012, 51: 7783．
［20］ HO C J, GAO J Y. An experimental study on melting heat transfer of paraffin dispersed with Al2O3 nanoparticles in a vertical enclosure ［J］. International Journal of Heat and Mass Transfer, 2013, 61: 28．
［21］ ZENG Y, FAN L W, XIAO Y Q, et al. An experimental investigation of melting of nanoparticle enhanced phase change materials (NePCMs) in a bottom heated vertical cylindrical cavity ［J］. International Journal of Heat and Mass Transfer, 2013, 66: 111117．
［22］ FAN L W, ZHU Z Q, ZENG Y, et al. Heat transfer during melting of graphene based composite phase change materials heated from below ［J］. International Journal of Heat and Mass Transfer, 2014, 79: 94104．
［23］ FAN L W, ZHU Z Q, ZENG Y, et al. Unconstrained melting heat transfer in a spherical container revisited in the presence of nano enhanced phase change materials (NePCM) ［J］. International Journal of Heat and Mass Transfer, 2016,95:10571069．
［24］ 丁晴, 方昕, 闫晨, 等. 石墨纳米片尺寸对复合相变材料储热特性的影响［J］. 化工学报, 2015, 66(6): 20232030．
DING Qing, FANG Xin, YAN Chen, et al. Effects of graphite nanosheet size on thermal storage property of composite PCMs ［J］. CIESC Journal, 2015, 66(6): 20232030．
［25］ FANG X, FAN L W, DING Q, et al. Increased thermal conductivity of eicosane based composite phase change materials in the presence of graphene nanoplatelets ［J］. Energy and Fuels, 2013, 27(7): 40414047．
［26］ 丁晴, 方昕, 范利武, 等. 混合纳米填料对复合相变材料导热系数的影响［J］. 浙江大学学报：工学版, 2015, 49(2): 330335．
DING Qing, FANG Xin, FAN Li wu, et al. Effect of hybrid nanofillers on thermal conductivity of composite phase change materials ［J］. Journal of Zhejiang University:Engineering Science, 2015, 49(2): 330335．
