Enhanced thermal performance of shell and tube phase change heat accumulator with novel biomimetic spider web fins

Abstract

Shell and tube phase change heat accumulator (STPCA) has many advantages such as flexible arrangement, simple structure and high operation temperature and pressure. However, there are some limitations such as the low thermal conductivity of phase change material (PCM) and much un-melted PCM at the bottom of STPCA. In this contribution, in order to solve aforementioned problems of STPCA, we firstly designed novel biomimetic spider web fins and applied the enthalpy-porosity method to solve the problem of phase transition and obtain the liquid fraction and location of the solid–liquid interface at different times. Then, we compared the enhance heat storage effect of the novel fins with that of normal radial fins. In addition, we further analyze the effects of three different fin arrangements and four different fin radial angles on the thermal storage performance. The results show that the novel biomimetic spider web fins can accelerate the melting of PCM at the bottom of the accumulator, uniform the temperature distribution and greatly improve the heat storage rate of the accumulator. The complete melting time of PCM of the accumulator with the novel web fins is only 48 s, but the radial fins is 140 s, which is much longer than that of the accumulator with the novel web fins. Moreover, the radial angle mainly affects the later melting period, because the angle can affect the natural convection. In this work, the model with a radial angle of 75° shows the better thermal storage performance. This contribution can provide a guidance for STPCA design to improve the heat storage performance.