%A Huilin ZHOU,Yan QIU %T Phase change characteristics of paraffin in rectangular storage unit %0 Journal Article %D 2019 %J Journal of Shandong University(Engineering Science) %R 10.6040/j.issn.1672-3961.0.2019.018 %P 99-107 %V 49 %N 4 %U {http://gxbwk.njournal.sdu.edu.cn/CN/abstract/article_1850.shtml} %8 2019-08-20 %X

To study the heat transfer characteristics of phase change material (PCM) in a storage unit and improve the heat transfer efficiency of phase change heat exchanger, the enthalpy-porous media model and FLUENT program were used to carry out a numerical investigation on the heat transfer process of paraffin in a rectangular heat storage unit. The element liquid fraction β and dimensionless Fo, Ste and Ra were introduced to analyze the influences of different positions outside the tube and inlet temperatures of heat transfer fluid on the melting and solidification process of paraffin. The results showed that the paraffin outside the tube was melted in order from the upper to the left/right part, then the lower part. The total melting time of paraffin in upper part was shorten by at least 20% compared with other parts. Conversely, in the heat release process, the paraffin was solidified in order from the lower, the left/right part and the upper part. The heat transfer mechanism in the unit changed gradually from heat conduction to natural convection in the thermal storage process. The efficiency of heat storage and release could be improved significantly by increasing the temperature difference between heat transfer fluid and paraffin. The criterion of β was obtained by polynomial fitting.