Experimental studies on the supercooling and melting/freezing characteristics of nano-copper/sodium acetate trihydrate composite phase change materials

This paper reports that Nano-copper (Nano-Cu), which possesses high thermal and electrical conductivity, as an additive, can improve the supercooling properties of sodium acetate trihydrate (CH 3 COONa·3H 2 O, SAT) and enhance its thermal conductivity . To investigate the effect of Nano-Cu content on the degree of supercooling of SAT, composite phase change materials containing SAT, Nano-Cu (0.4%, 0.5%, 0.6%, 0.7% and 0.8%), CMC (thickening agent) and sodium dodecyl sulfonate (C 12 H 25 NaO 3 S, dispersant) were prepared. Melting-freezing experiments involving the composite materials indicated that the rate of heat transfer increased by nearly 20%. When an optimal amount of Nano-Cu (i.e., 0.5%) was added to SAT, the degree of supercooling was reduced to approximately 0.5 °C. Compared to the use of inorganic salt hydrates as nucleating agents , Nano-Cu is significantly advantageous in reducing the degree of supercooling of SAT. The maximum improvement in supercooling was observed when the melting-freezing experiment was conducted at an initial temperature of 70 °C. The thermal conductivity of the reported composite phasechange materialsis approximately 20% higher than that of pure SAT.