Influence of the Fin Design on the Melting and Solidification Process of NaNO3 in a Thermal Energy Storage System

Abstract

Abstract:The melting and solidification process of sodium nitrate, which is used as energy storage material, is studied in a vertical arranged energy storage device with two different bimetal finned tube designs (with and without additional lateral fins) for enhancing the heat transfer. The finned tube design consists of a plain steel tube while the material for the longitudinal (axial) fins is aluminum. The investigation analyses the influence of the lateral fins on the charging and discharging process. Three-dimensional transient numerical simulations are performed using the ANSYS Fluent 14.5 software. The results show that, every obstruction given by lateral fins reduces the melting and solidification velocity in direction to the outer shell.

Heat Transfer in Latent High-Temperature Thermal Energy Storage Systems—Experimental Investigation

“…It is not stationary after six hours of discharging. The solidification process of the PCM takes more time than the melting, which confirms numerical simulation as in [29] and former measurements as in [23]. In the axial direction, the vessel is split into five vertical sections by transversal fins.…”

“…Furthermore, the temperature gradient between the PCM and the HTF is high; hot and liquid PCM accumulates at the top of each section. Natural convection plays a non-negligible role in the heat-transfer mechanism during melting, as previously described by Walter in [29]. For solidification, the axial temperature distribution is uniform, heat conduction is the dominating and limiting factor for the heat transmission.…”

“…Different fin positions are focused on in [26] or [27], and fins versus pins are investigated in [28]. The influence of the fin design is shown in [29,30]. Three main findings can be summarized from the mentioned literature.…”

An investigation of measurement method and phase change in a latent heat energy storage device

“…Failure to address these issues has long-term, and likely irreversible, global health, environmental and economic consequences [16,17,18] . [19][20][21][22][23] . Among these methods, extended surfaces are the most popular choice as they are a simple and low-cost strategy for controlling the temperature gradient and lift within a given system [23][24][25] .…”