Experimental Investigation on Enhanced Energy Storage Characteristics of Spherically Encapsulated 1-Decanol/Expanded Graphite Composite for Cold Storage System

Abstract

The low solidification temperature (0°C), sporadic nucleation behaviour and supercooling phenomenon of ice are the major factors affecting the energy storage efficiency of an ice-based cold thermal energy storage system (CTESS). Due to the non-supercooling nature and high solidification temperature (~4.1°C), 1-Decanol-Expanded graphite composite (CPCM) is proposed as a prospective replacement for ice in CTESS. The CPCM was macro encapsulated inside the various diameter (42, 51 and 64 mm) spherical enclosures (S.Es), and its energy storage performance was studied at different wall temperatures (Tw) for charging (0,-3 and -6°C) and discharging (10, 13 and 16°C). It is found that the latent heat can be stored in CPCM even at a higher wall temperature (-3°C), which is not possible in the case of ice. To freeze the same mass of 1-Decanol at Tw = -6°C, the CPCM filled 51 mm S.E requires 85.37% lower time than that of PCM filled S.E. Based on experimental results, -3 and 13°C is found as an optimum wall temperature for charging and discharging, respectively. The charging and discharging rates increase with diameter. Besides, in a 51 mm S.E, the time required to store (Tw = -3°C) and recover (Tw = 16°C) a stated amount of energy in CPCM is 81.27%, and 76.45% lower than that of PCM, respectively. CPCM has superior phase change and energy storage characteristics. Therefore, the use of CPCM in CTESS ensures effective storage and recovery of cold energy.