水基纳米TiO_2复合相变材料的制备及性能

Preparation and Properties of Water-based Nano-TiO_2 Composite Phase Change Material

针对水作为冷藏保鲜领域常见的蓄冷剂存在相变时过冷度大、导热系数小的现象,研制了一种以水作为基液,添加纳米粒子及分散剂的复合相变材料,该材料配方质量比为水+0.7%纳米二氧化钛(TiO_2)+1.0%十二烷基苯磺酸钠(SDBS),相变温度为0.216℃,相变潜热为353.1 k J/kg。在水中加入纳米TiO_2使水在相变过程的过冷度降低了5~6℃,且导热系数较基液提高了62.7%,从0.598 8 W/(m·K)升至0.974 5 W/(m·K);同时添加分散剂SDBS,改善了水基纳米TiO_2的沉降问题,提高了材料的稳定性,防止相分离。结合理论与实验,总结分析了纳米TiO_2与分散剂SDBS不同质量比的水基纳米复合相变材料的热性能,确定纳米TiO_2与分散剂SDBS在水中的最佳质量添加比为7∶10。通过最优例材料静置后的颜色观察和导热系数测试,表明纳米TiO_2在水中具有良好的分散稳定性。

Water is a frequently used cool storage material in the field of refrigeration and food preservation. Because of the large super-cooling degree during the phase change period and the low thermal conductivity of water, a composite water-based phase change material containing nanoparticles and a dispersing agent was developed. The mass ratio of the material is H2O＋ 0. 7% nano-TiO2 ＋1.0% sodium dodecyl benzene sulfonate （SDBS）. The phase change temperature of the composite phase change material is 0. 216 and the latent heat is 353. 1 kj/kg. By adding nano-TiO2, the supercooling degree of water can be reduced by 5-6 , while the thermal conductivity increa-ses by 62. 7% , from 0. 598 8 to 0. 974 5 W/（ m＊ K）. Moreover, adding the dispersing agent SDBS improves the sedimentation problems of water-based nano-TiO2, enhances the stability of the material, and prevents the phase separation phenomenon. Through theoretical and experimental analyses of the thermal properties of the composite phase change material with different nano-TiO2 and SDBS ratios, the opti-mal mass ratio is determined to be 7- 10. The color and thermal conductivity of the optimal material after the installation indicate that nano-TiO2 has good dispersion stability in water.