为了研究注液氮降温对煤自燃的影响，选取亭南煤矿二盘区和三盘区煤样进行热物性实验。首先通过LFA457激光闪射仪对煤样进行预处理，再测定煤样30～300 ℃范围内的热物性参数，得到注液氮降温后煤样热物性参数随温度的变化规律，对比分析注液氮前后影响煤样热物理性质的因素。结果表明：注液氮处理前后的煤样，二者的热扩散系数都随着温度的升高而降低，比热容与导热系数随着温度的升高而上升；在30～200 ℃范围内，注液氮处理后煤样的热物性参数平均变化率高于原煤样，说明注液氮处理会增加煤样对温度的敏感性；此外，在相同温度下，注液氮处理后煤样热物性参数相较原煤样均有不同程度的上升，热扩散系数平均增长率最高，表明注液氮处理后的煤样在氧化升温过程中热扩散能力增强。

In order to study the effect of liquid nitrogen injection cooling on spontaneous combustion of coal, coal samples from the second and third panel areas of Tingnan Coal Mine were selected for thermal and physical property experiments. First, the coal sample was pretreated by LFA457 laser flash analyzer, and then the thermophysical property parameters of the coal sample were measured in the range of 30-300 ℃, and the change law of the thermophysical property parameters of the coal sample with temperature was obtained after liquid nitrogen injection and cooling, and the factors affecting the thermophysical properties of the coal sample were compared and analyzed. The results show that the thermal diffusivity decreases with the increase of temperature, and the specific heat capacity and thermal conductivity increase with the increase of temperature; in the range of 30-200 ℃, the average change rate of thermal property parameters of coal samples after liquid nitrogen injection treatment is higher than that of raw coal samples, indicating that liquid nitrogen injection treatment will increase the sensitivity of coal samples to temperature; in addition, at the same temperature, the thermal physical property parameters of coal samples after liquid nitrogen injection treatment increased to different degrees compared with the original coal samples, and the average growth rate of thermal diffusion coefficient was the highest, indicating that the thermal diffusion ability of coal samples after liquid nitrogen injection treatment was enhanced during the oxidation and heating process.