Experimental investigation on the thermal storage performance of nanocomposite-enhanced fatty acid eutectic PCM and the effect of ultrasonic vibration for application in cold storage

This study investigates the thermal properties of a eutectic mixture of oleic acid and capric acid (OA-CA) dispersed with a coconut shell-activated carbon cobalt oxide nanocomposite (CSAC-Co3O4) for thermal energy storage. The effects of ultrasonic waves on the phase change characteristics of the PCM are also analyzed. The prepared novel hybrid nanocomposite material of coconut shell-activated carbon cobalt oxide (CSAC-Co3O4) acts as a nucleating agent in the PCM, to improve the thermal properties. The EDX confirms the atomic composition of the prepared CSAC-Co3O4 nanocomposite and FTIR evidences the physical bond of the CSAC-Co3O4 with OA-CA eutectic PCM. The addition of CSAC-Co3O4 hybrid nanocomposite to OA-CA eutectic PCM increased thermal conductivity to 73 % at 0.1 wt% compared to OA-CA pure eutectic PCM. The thermal expansion coefficients of the developed eutectic phase change material (PCM) and CSAC-Co3O4 composite-enhanced PCM ranged from 2.12 x 10(-3) degrees C(-1)to 2.95 x 10(-3) degrees C-1. The prepared NCPCMs are hydrophilic and have a contact angle in the expected range. The latent heat storage of the CSAC-Co3O4 composite-enhanced PCM was found to be 77.67 kJ/kg for freezing and 79.05 kJ/kg for melting. The phase transition was accelerated due to the particle addition by 20 % for 0.1 wt%. The effects of ultrasonic vibration, improved the rate of phase change by 1.3 times. Thus the novel CSAC-Co3O4 enhanced composite PCM has better storage performance and serves as an active low-temperature thermal energy storage medium for cool thermal energy storage.