相变微胶囊改性砂浆界面传热机理研究

Mechanism investigation on interface heat transfer of phase change microcapsule modified mortar

以二氧化硅为壳材、石蜡为芯材制备相变微胶囊,并与水泥掺混制备相变微胶囊改性砂浆,研究相变微胶囊掺量对改性砂浆热性能的影响。研究表明,随着微胶囊掺量增加,改性砂浆试样的内表面温度降低,升温速率下降,导热系数减小。当相变微胶囊掺量为20%时,导热系数较纯砂浆试样降低了0.49 W/(m·K)。基于COMSOL软件,建立有限元模型,从微观尺度分析相变过程传热机理,以及相变微胶囊与水泥砂浆基质接触界面的传热情况。试块的外表面受热温度为50℃时,添加相变微胶囊的水泥砂浆内表面温度和中心剖切面温度较纯水泥砂浆分别降低0.30、1.16℃。

Phase change microcapsules were prepared by using silica(SiO_(2))as shell material and paraffin as core material,and then mixed with cement to prepare phase change microcapsules modified mortar(SiO_(2)-MEPCM).The influence of phase change microcapsules with different dosage on the thermal properties of modified cement mortar was studied.The results show that with the increase of microcapsule content,the inner surface temperature of the modified mortar sample decreases,the heating rate decreases,and the thermal conductivity decreases.When the content of phase change microcapsule is 20%,the thermal conductivity is reduced by 0.49 W/(m·K)compared with the pure mortar sample.Based on COMSOL software,the finite element model was established to analyze the heat transfer mechanism of phase transition process and the heat transfer at the contact interface between phase transition microcapsule and cement mortar matrix from the microscopic scale.When the temperature of the outer surface of the test block was 50℃,the inner surface temperature and central section surface temperature of the cement mortar test block with phase change microcapsule decreased by 0.30℃and 1.16℃,respectively,compared with the pure cement mortar test block.