The rational use of energy is of great significance for the long-term stable development of the economy. However, energy such as solar energy and industrial waste heat are difficult to be utilized stably. The development of thermal storage technology can alleviate the instability of energy. In this paper, 96 wt% NaNO₃-4 wt% NaCl (NN) was used as the thermal storage material and expanded graphite (EG) was used to adsorb NN binary phase change material (PCM). The effect of EG with different particle sizes on the thermal performance of NaNO₃–NaCl/EG composite phase change material (CPCM) was studied. The results showed that the addition of EG reduced the supercooling degree of NN from 4.7 °C to 1.1 °C. The addition of EG powder increased the contact probability between fillers and provided more adsorption positions for PCM, increasing the latent heat of composites. The addition of 32 mesh EG–EG powder greatly increased the thermal conductivity of NN from 1.24 W·m⁻¹·K⁻¹ to 5.43 W·m⁻¹·K⁻¹. It is because the pores of large particle size EG are filled with EG powder, which is easy to form chain or network structure, forming more heat conduction pathways. The research provides some technical support for the application of phase change heat storage technology.

能源的合理利用对于经济的长期稳定发展具有重要意义。然而，太阳能、工业废热等能源却难以稳定利用。储热技术的发展可以缓解能源的不稳定性。本文采用96 wt% NaNO ₃ -4 wt% NaCl（NN）作为蓄热材料，并采用膨胀石墨（EG）吸附NN二元相变材料（PCM）。研究了不同粒径的EG对NaNO ₃ –NaCl/EG复合相变材料(CPCM)热性能的影响。结果表明，EG的添加使NN的过冷度从4.7℃降低到1.1℃。EG粉末的添加增加了填料之间的接触概率，为PCM提供了更多的吸附位置，增加了复合材料的潜热。32目EG-EG粉末的添加使NN的热导率从1.24 W·m ^-1 ·K ^-1大大增加到5.43 W·m ^-1 ·K ^-1。这是因为大粒径EG的孔隙中充满了EG粉末，易于形成链状或网状结构，形成更多的导热通路。该研究为相变储热技术的应用提供了一定的技术支撑。