Ag nanomaterials enabled simultaneous thermal storage and heat transfer enhancement of CH3COONa·3H2O/vermiculite composite phase change material

Abstract

Filling thermally conductive materials (TCMs) is an effectivity way to enhance the thermal conduction of phase change materials (PCMs). However, it always has negative effects on heat storage behavior of PCMs. Balance of latent heat and thermal conduction capacity plays a vital role in practical application of thermal storage management. To study the effect of dimensional features of TCM on thermal characteristic of PCM, Ag nanomaterials (Ag NMs) which including 0-dimensional Ag nanoparticles (AgNP), 1-dimensional Ag nanowires (AgNW) and 2-dimensional Ag nanosheets (AgNS) acted as TCM, were used to modify the flaky expended vermiculate (EVM-Ag NMs), a series of CH₃COONa·3H₂O (SAT)/EVM-Ag NM composite PCMs (SAT/EVM-Ag NM CPCMs) were prepared. It was found that the Ag NMs contributed to the phase change behavior of hydrated salts. Wherein, the SAT/EVM-AgNW CPCM possessed high latent heat (∼200.9 J/g) and great thermal reliability (heat enthalpy loss was 6.9 % after 500 thermal cycles). Besides, Ag NMs also improved the thermal conductivity of the CPCMs. The Ag NWs formed interconnected thermal highways which was benefited to enhance thermal conductivity (0.8153 W·K⁻¹·m⁻¹). This work provides a new strategy for simultaneously improving the thermal conductivity and heat storage behavior of PCM, finds a new perspective to explore the mechanism of TCMs on phase change behavior and heat conduction of PCM.