Chinese Journal of Chemical Engineering ›› 2020, Vol. 28 ›› Issue (11): 2857-2871.doi: 10.1016/j.cjche.2020.08.022

• Energy, Resources and Environmental Technology • Previous Articles     Next Articles

Melting heat transfer enhancement of a horizontal latent heat storage unit by fern-fractal fins

Zilong Deng1, Suchen Wu1, Hao Xu2, Yongping Chen1,2   

  1. 1 Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China;
    2 Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
  • Received:2020-03-21 Revised:2020-07-19 Online:2020-11-28 Published:2020-12-31
  • Contact: Yongping Chen
  • Supported by:
    This work was supported by the National Key R&D Program of China (2019YFB1504301), National Natural Science Foundation of China (51725602, 51906039), and Natural Science Foundation of Jiangsu Province (BK20180405).

Abstract: The latent heat storage (LHS) technique is of crucial importance in chemical energy engineering. Inspired by multi-bifurcated fern leaves, a mimic fern-fractal fin is designed to improve the thermal energy charging efficiency. This paper develops a transient melting model of a rectangular LHS unit using fern-fractal fins, and their melting behaviors are compared with the conventional fins. Besides, a parametric optimization of fernfractal fins is conducted for maximizing the thermal efficiency based on the response surface method (RSM). The results indicate that the temperature uniformity is more superior and the melting duration is shorter for the fern-fractal LHS unit when compared with the conventional one. Interestingly, the fern-fractal LHS device presents a slower heat storage rate during the initial conduction-dominated and early convection-dominated melting stages, while a prominent melting enhancement is achieved during the later melting stage. The shortest melting time is obtained based on the RSM technique when a fern-fractal fin with length ratio α=0.94 and branch angle θ=54.7° is utilized. Compared with a conventional fin, the averaged heat storage rate increases by 88.3%, and the total melting time is declined by 40.3% for an optimized fern-fractal fin.

Key words: Multiscale, Fractal, Numerical simulation, Heat storage, Optimization