Abstract:

Thermal endurance of phase change materials is of significance in real-world latent heat storage. The binary eutectic mixtures of D-dulcitol/inositol for medium temperature latent heat storage was prepared by mixing their melts at given molar ratio and then cooled to be solidified in the present study. The mixture samples were heated using a vacuum tube furnace at four temperatures (463, 473, 483 and 493 K), and for each temperature point, the heating was lasted for 5, 10, 15 and 20 h. The latent heat of fusion of the mixtures were measured by a differential scanning calorimetry. The thermal degradation characteristics of the mixtures were analyzed using a constant temperature kinetic model based on the change of latent heat of fusion. In addition, the thermal endurance of the mixture was improved by adding the antioxidant 1010 (at 1.0%(mass)). The results showed that after heating at 463 K for 20 h, the enthalpy of the eutectic sugar alcohol decreased by 24.9%; after adding the antioxidant, its enthalpy decreased by only 8.25%. It was determined that the thermal degradation duration of the mixture was 154 h when its latent heat of fusion decreased a half at 463 K. By contrast, the duration increased about 4 times after adding the antioxidant. With temperature increasing to 473, 483 and 493 K, the thermal degradation durations of the mixture increased about 2.6, 1.6, and 1.1 times, and their thermal degradation rates decreased by 62.65%, 40.42%, 6.51%, respectively. The results showed that using the antioxidant 1010 can improve the thermal endurance of the mixture sugar alcohol.

Key words: thermal endurance, sugar alcohol, binary eutectic mixture, phase change material, latent heat storage, antioxidant

摘要：

相变材料的热稳定性在实际相变储热应用中至关重要。通过熔融共混的方法制备了可用于中温储热的D-半乳糖醇（69%（mol））/肌糖醇二元共晶相变材料，使用真空管式炉分别在463、473、483和493 K温度下将该共晶混合物加热5、10、15和20 h。然后采用差示扫描量热仪测量试样的熔化焓，并采用基于焓值变化的恒温动力学模型分析其焓值热降解特性，从而对其热稳定性进行评价。此外，采用添加抗氧化剂1010（1.0%（质量））的方法提高共晶糖醇的热稳定性。结果表明，在463 K温度下加热20 h后，共晶糖醇焓值下降24.9%；添加抗氧化剂后，其焓值仅下降8.25%。采用恒温动力学模型计算发现，共晶糖醇在463 K温度下焓值下降一半所用的时间为154 h，添加抗氧化剂1010后，其热降解时间增加约4倍。当加热温度升高至473、483、493 K时，热降解时间分别提高约2.6、1.6、1.1倍，热降解速率 k值分别降低62.65%、40.42%、6.51%。结果表明添加抗氧化剂可有效提高共晶糖醇的热稳定性。

关键词: 热稳定性, 糖醇, 二元共晶混合物, 相变材料, 储热, 抗氧化剂