Annulus eccentric analysis of the melting and solidification behavior in a horizontal tube-in-shell storage unit

Abstract

Abstract Previously, optimal eccentric parameters were considered to be greatly overall size- dependent, but the inherent factor haven’t been determined. In this study, we suggest that areas above and below inner tube may be the core factor, based on this, “eccentric space ratio” is proposed to explore the thermal behavior of phase change material in different radius ratio models. The results indicate the melting period can be shortened by more than 40% between 4:1 and 14:1, as is generally valid for different radius ratios. Additionally, the solidification can be shortened consistently by more than 45% between 1:4 and 1:14 in large radius ratios models which breaks the previous consensus, but still extended for small radius ratios models. Remarkably, optimal eccentric range in solidification is symmetrical with that in melting. With these numerical and mechanistic analyses, we find that areas above and below inner tube can significantly influence natural convection and temperature distribution, while, as a simple approximation, “eccentric space ratio” is well employed to analyze the area effect irrespective of diameters. Further, this analysis strategy provides a robust optimal eccentric parameter range for phase change heat exchangers and can be widely applied in rapid latent heat storage.