Study on the effect of multiple spiral fins for improved phase change process

The finned cylindrical annulus is an efficient latent heat thermal energy storage system which can significantly improve the low thermal conduction of phase change materials. In this study, for improving the low thermal conduction of PCM, the enhancement efficiency of the novel multiple spiral fins compared with longitudinal fins has been numerically investigated. The enthalpy-porosity technique is used to study the heat transfer and phase change process of this transient model. The melting and solidification rates of PCM in the annulus with 4, 8, 16 spiral fins and three kinds of distortion degrees of fins have been discussed. Results show that the total melting time and solidification time of PCM in annulus with spiral fins could be maximally saved to 57.60% and 74.13% compared to the longitudinal fins when the fin number is fixed. When the distortion degree is the same, the melting time and solidification time could be maximally saved to 60.88% and 73.49% compared to 4 fins. Besides, fin spacing is used to describe the overall effect of fin number and distortion degree. The similar fin spacing which is consisted of different fin numbers and distortion degrees would achieve a similar heat transfer process.