Experimental analysis of submerged coil and encapsulated slab latent heat storage. (5th June 2022)

• Record Type: Journal Article
• Authors: Hu, Ming-Hsuan; Xu, Tianhao; Chiu, Justin NW.
• Is Part Of: Applied thermal engineering. Volume 209(2022)
• Publication Date: 2022-06-05
• Subjects: Phase change materials -- Thermal energy storage -- Experimental study -- Spiral coil heat exchanger -- Slab encapsulation; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2022.118259
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Experimental data for slab encapsulation and submerged coil performance are obtained. Storage with constant and time varying flowrates are evaluated. Partial charging/discharging demonstrates higher mean thermal power. Submerged spiral coil heat exchanger allows higher storage density. Slab encapsulation can meet higher thermal power demand. Abstract: Latent heat thermal energy storage (LHTES) has two primary LHTES packing methods, encapsulation and bulk PCM storage. Since there is still a lack of experimental comparison between these two methods, two types of LHTES units based on separated methods were built for direct comparison. Moreover, the impact of heat transfer fluid (HTF) flowrate on LHTES performance was evaluated. Unit one is a 0.38 m 3 tank containing slab-shaped macro-encapsulated phase change material (PCM); unit two is a 0.54 m 3 tank containing submerged spiral coil heat exchanger (SCHE) in PCM. PCM with a melting temperature of 58–60 °C was charged/discharged between 46 and 72 °C. Parametric studies on constant and time-varying HTF flowrates were conducted to test the impact on the thermal storage performance. The time-varying flowrate control enables the system to supply the needed power at different discharging stages. Moreover, partial charging/discharging demonstrates higher mean thermal power than full charge/discharge rendering this control strategy adequate under specific operating conditions. Finally, the comparison between the slab-encapsulated PCM storage unit and the SCHE based unit shows that the former requires a shorter completion time while the latter has a higher energy storage density.