Abstract In this paper, we report on the measurement of the thermal diffusivity of heptane-isooctane mixtures in the liquid phase at room temperature and atmospheric pressure using the mode-mismatched dual-beam transient thermal lens technique. We found a good agreement between the thermal diffusivity values measured here directly and those determined indirectly in a previously published report. The most significant differences were observed at lower isooctane concentrations, being attributed to the effect of molecular London dispersive forces. We demonstrated that the behavior of the thermal diffusivity as a function of the relative mass fractions follows an empirical model for interacting binary mixtures, which not only accounts for deviations from the law of additivity in the thermal conductivity but also in the heat capacity per unit volume. The highest deviation from the linearity expected using the additivity rule was about 11 %, at a relative mass fraction of 50 wt %.

中文翻译：

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庚烷-异辛烷混合物的热扩散率

摘要 在本文中，我们报告了使用模式失配双光束瞬态热透镜技术在室温和大气压下测量液相中庚烷-异辛烷混合物的热扩散率。我们发现此处直接测量的热扩散率值与先前发表的报告中间接确定的热扩散率值之间具有良好的一致性。在较低的异辛烷浓度下观察到最显着的差异，这归因于分子伦敦色散力的影响。我们证明了作为相对质量分数的函数的热扩散率的行为遵循相互作用的二元混合物的经验模型，这不仅解释了与热导率相加定律的偏差，而且还解释了每单位体积的热容量.