Investigation on the anti-supercooling effect of sodium polyacrylate as an additive in phase change materials for the applications of latent heat thermal energy storage

Abstract Supercooling is an undesirable thermal effect that occurs in most latent thermal storage applications. It reduces the energy performance and generates additional energy consumption in refrigeration systems. We evaluate, as a novel solution to this problem, the potential of combining the Sodium Polyacrylate polymer (SP) with a phase change material (PCM) in order to depress this latter's supercooling degree. Samples of the solutions with different volumes were prepared by adding SP particles to three PCMs at liquid phase: water, ethylene glycol solution at 23%, and NaCl salt solution at 13%. SP-PCM couples present a stable gel structure above the PCM's solidification temperature, which prevents leaks during storage and transport. Differential scanning calorimetry (DSC) and cooling test series were conducted below the PCM solidification temperature in order to measure the thermo-physical properties of the SP-water couple, and to define the effect of the volume sample on the supercooling degree. Experiments show that depending on the sample volume, the SP polymer reduces or even totally eliminates supercooling during the solidification of the PCM, while the latter's physical properties are kept unchanged. Our results suggest that the addition of SP to PCMs helps inducing nucleation and reduces leakage, which leads to a reduction in the energy consumption of the PCM's solidification process for cold thermal storage applications.