科研之友
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摘要
NaCl-MgCl2 eutectic salt and α-Al2O3 are selected as phase change material (PCM) and encapsulation material, respectively. Six kinds of NaCl-MgCl2 eutectic salt/α-Al2O3 ceramic medium-high temperature composite phase change material (CPCM) with different mass ratios are prepared by spark plasma sintering (SPS) process. The microstructure and thermodynamic properties of CPCM are analyzed by scanning electron microscope (SEM), electron probe micro-analysis (EPMA), X-ray diffraction (XRD), high temperature laser thermal conductivity meter and differential scanning calorimeter-thermogravimetric analyzer (TG-DSC). The charging and discharging rates of CPCM are analyzed by finite element simulation. The results show that after sintered at 550 ℃, α-Al2O3 ceramic plays a good role in encapsulation and effectively reduces the weight loss rate of NaCl-MgCl2 eutectic salt at high temperature. Compared with NaCl-MgCl2 eutectic salt, the overall thermal conductivity of CPCM is significantly improved, and the phase change time is greatly shortened, indicating that the heat charging and discharging rates of CPCM are significantly improved. The medium-high temperature CPCM has dense microstructure, and the distribution of all elements in CPCM is relatively uniform. The distribution of Na and Mg elements is superposition, indicating that there is no chemical reaction between NaCl-MgCl2 eutectic salt and α-Al2O3, and CPCM has good chemical stability. The melting point of NaCl-MgCl2 eutectic salt/α-Al2O3 ceramic medium-high temperature CPCM is 408.7 ℃, the latent heat of phase transition is 142.6 J/g, and the thermal stability is good at 500-650 ℃. This paper provides a novel experimental basis for the preparation and characterization of eutectic salt/ceramic CPCM.
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