As a low-cost and high-density heat storage material, sodium acetate trihydrate with sodium carboxymethyl cellulose (CMC) as a thickening agent and disodium hydrogen phosphate dodecahydrate (DSP) as a nucleating agent has the advantages of good thermal cycle stability and low supercooling degree. However, the optimal concentration and mechanism of the additives are unclear. In this study, the effects of viscosity grades of CMC and additives (CMC and DSP) of different concentrations on the cyclic thermal stability, thermal properties and phase change behavior of cPCMs were examined. The results showed that CMC with a high viscosity has a remarkable ability to maintain the thermal cycle stability of the cPCMs. However, a poor phase change behavior (decreased latent heat and increased supercooling degree) was observed with high-viscosity CMC as the thickening agent. It was also observed that excessive use of CMC or DSP results in a poor thermal stability and high supercooling degree. In addition, the viscosity of the cPCMs decayed irreversibly after several thermal cycles because of the degradation and weakened entanglement, which challenges the ability of CMC to cope with long thermal cycle environments.

中文翻译：

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添加剂对三水乙酸钠相变材料循环热稳定性和热性能影响的实验研究

三水醋酸钠作为一种低成本、高密度的蓄热材料，以羧甲基纤维素钠（CMC）为增稠剂、十二水磷酸氢二钠（DSP）为成核剂，具有热循环稳定性好、过冷度低等优点程度。然而，添加剂的最佳浓度和作用机制尚不清楚。在这项研究中，研究了不同浓度的CMC和添加剂（CMC和DSP）的粘度等级对cPCM的循环热稳定性、热性能和相变行为的影响。结果表明，高粘度的CMC具有显着的维持cPCM热循环稳定性的能力。然而，使用高粘度 CMC 作为增稠剂时，观察到相变行为较差（潜热降低和过冷度增加）。还观察到，过多使用CMC或DSP会导致热稳定性差和过冷度高。此外，由于降解和缠结减弱，经过几次热循环后，cPCM的粘度不可逆地衰减，这对CMC应对长热循环环境的能力提出了挑战。