煤火灾害是煤炭开采过程中主要灾害之一，它不仅造成资源浪费，还会威胁煤矿安全，污染环境，破坏生态系统，因此煤火灾害防治是矿井安全生产的重要任务。近年来，随着CO2输送与储存技术的提高，液态CO2被成功的应用于采空区煤火灾害的治理当中，取得了显著的灭火效果，受到了众多学者的广泛关注。然而，在利用液态CO2对矿井火区进行治理过程中，对液态CO2注入高温松散煤体后的惰化和降温规律掌握不明，从而无法科学的设计液态CO2灌注参数。为此本文围绕液态CO2注入高温松散煤体后的相变降温与扩散过程进行研究。取得了以下研究成果： （1）基于采空区煤自燃特性以及液态CO2相变降温特征，搭建了煤自燃CO2降温模拟实验台，该实验台不仅可用于测试高温火区内注入液态CO2后的惰化和降温效果、渗流规律、扩散规律，还可以用于煤自燃发火期测试以及其它灭火剂的灭火效果测定。 （2）通过煤自燃CO2降温模拟试验台进行了松散煤体内液态CO2降温实验，得到了注入液态CO2过程中以及停止注入CO2后松散煤体内前后两个火区的降温规律，并得到各平面内降温区域分布特征。 （3）在基于渗流场、浓度场和能量场多物理场耦合的基础上，建立了液态CO2在高温松散煤体内释放后的相变吸热降温及扩散的数值模型，得到了松散煤体内CO2渗流速度分布特征、CO2扩散特征、煤体降温过程。并通过实验对比，验证了模型的准确性。 （4）通过对不同参数下松散煤体内液态CO2惰化和降温规律的数值模拟计算，确定了液态CO2压注量、释放管路释放口径、释放管路偏移容器轴线距离、释放口与火源中心的距离对松散煤体内各火区降温效果的影响，并得到了多因素下松散煤体内高温火区降温幅度关系式。

ABSTRACT The disaster of coal fire is one of the main disasters in coal mining. It not only causes waste of resources, but also threatens the safety of mine, pollutes the environment and destroys the ecosystem. Therefore, the prevention and control of coal fire is an urgent problem. In recent years, as the improvement of CO2 transport and storage technology, the successful application of liquid CO2 in the treatment of coal fire, the liquid CO2 has been successfully applied to the control of coal fire in goaf, and it has achieved remarkable fire fighting effect, which has been widely concerned by many scholars. However, when the liquid CO2 injected into high-temperature loose coal, the effect of inerting and cooling of coal are unclear, resulting it impossible to design the injection parameters of liquid CO2 scientifically. Therefore, this paper focuses on the study of the effect of cooling and diffusion after liquid CO2 injected into high-temperature loose coal. Based on the characteristics of coal spontaneous combustion in gob and the phase change and cooling of liquid CO2, an experiment platform for coal spontaneous combustion-cooling is established. The experiment platform not only can be used to examine the effect of inerting and cooling, the law of seepage and diffusion after liquid CO2 injected into high-temperature loose coal, but also can be used to determine the spontaneous combustion period of coal and the fire control effect of other fire extinguishing agents. Based on the coal spontaneous combustion-cooling experiment platform, the liquid CO2 cooling experiment in high-temperature loose coal was carried out, and the cooling effect of two fire zones in test container was achieved after the liquid CO2 injected into loose coal, and the distribution of the cooling regions in plane is displayed. According to seepage, component and energy field, a fully coupled numerical model of liquid CO2 released in loose coal is developed to investigate cooling and diffusion of CO2. Meanwhile the accuracy of the model is verified by experiments. The characteristics of seepage velocity, CO2 diffusion and cooling in loose coal are shown. The relationship between the area of CO2 distribution and the amount of liquid CO2 which is injected into loose coal is determined. Based on the numerical simulation mode of liquid CO2 released in loose coal, the effect of cooling in loose coal under different parameters is calculated. It were evaluated that the amount of liquid CO2, the caliber of the release pipe, the distance from the axis to the release pipeline, distance between the release port and the center of the fire on the cooling effect in high-temperature loose coal by liqueur CO2. Subsequently, the mathematics model based on reduced temperature of fire zone in loose coal versus multi-influence factors was proposed.