Influence of flat tube aspect ratio on melting characteristics of phase change material within a double-tube unit

• DOI: 10.1016/j.csite.2025.105892
• Publication Date: 2025-02-16T23:20:48Z
• Authors: Gwan Gyu Kim; Chan Woo An; Young Min Seo; Seokho Kim; Hoon Ki Choi; Yong Gap Park
• Keywords: Phase-change material; Aspect ratio (aeronautics); Diameter ratio

In this study, a numerical analysis was performed to investigate how the aspect ratio of flat tubes in a double-tube latent thermal energy storage system affects the melting behavior and thermal transfer properties of N-eicosane. To simulate the melting characteristics of the systems, the enthalpy–porosity method was employed. The aspect ratios of flat tubes in the inner and outer configurations significantly affected the melting characteristics. A smaller aspect ratio of the inner flat tube (ARi) increased natural convection, resulting in a decreased total melting time. Conversely, a larger aspect ratio of the outer flat tube (ARo) decreased the amount of solid PCM remaining, which also contributed to a shorter total melting time. For instance, in case 13, the total melting time was 1223.5 s, which represents a 59.3 % reduction compared with case 46, i.e., the base case with circular double tubes. The mean power in case 13 was 261.2 W, which corresponded to an increase of 146.08 % compared with the base case. Furthermore, at the optimal performance of ARo = 1.8, correlation equations for total melting time and mean power were derived to assess the influence of ARi regarding the melting process of systems.