Improvement of the Subcooling Problem of Sodium Acetate Trihydrate by a Combination of Stirring or Internal Electric Field and Nucleating Agent

Energy storage devices are the hub of a multi-energy complementary distributed energy system.Hydrated salts are the most suitable phase change material for energy storage devices,but subcooling is the main obstacle to their application.Nucleation requires a driving force so the use of nucleating agents alone does not reduce subcooling to a very low level.To address this issue,this paper first screened nucleating agents and then further reduced the subcooling of sodium acetate trihydrate in conjunction with stirring or direct current.The effects of rotor mass,rotational speed,direct current voltage,and electrode material on nucleation were analyzed.Finally,the stability of the composite phase change material in the presence of simultaneous stirring and energization was analyzed.The results showed that the addition of 1.5%in weight of disodium hydrogen phosphate dodecahydrate to sodium acetate trihydrate can reduce the subcooling to about 2.3℃.Continued addition of stirring or electricity can reduce the subcooling of sodium acetate trihydrate to within 0.5℃ or even eliminate it.The higher the momentum of the stirring,the better the improvement in subcooling,phase separation,and thermal conductivity.The higher the direct current voltage,the better the nucleation effect,but the electrode life will be lower.The silver electrode has the best nucleation effect.No new material was produced in the solution after 100 cycles in the presence of both stirring and direct current.The melting point of the phase change material was increased by 0.2℃ and the latent heat value decreased by 1.8%,still with good stability.The trace of deionized water should be added to the phase change material in subsequent studies to compensate for the consumption ofwaterby theanodicelution.