采空区等隐蔽空间煤温的精准判识一直是亟待解决的世界性难题，研究声学测温技术对精准探测松散煤体温度具有重要的实际意义，而声速与煤温之间映射关系的科学准确构建是声学法测煤温的关键。为此，考虑松散煤体自燃进程特征参数对声波传播的影响，建立了松散煤体准多孔介质的声速−煤温映射关系模型；设计搭建了松散煤体声学测温实验系统，通过开展多种粒径(0.6～1.5、1～3、3～5 cm)松散煤体的声波测温试验，研究了不同粒径煤样低温氧化阶段(30～50 ℃)所产生的气体组分、体积分数对声传播的影响规律，确定了等效路径转换因子$ lambda $；基于实测声速与等效路径转换因子间的关系，提出并确定了气体组分介质修正系数$ varphi $，验证了声速−煤温映射关系模型的可行性。结果表明：松散煤体声波传播路径受煤体粒径、温度及气体组分介质变化量等特征参数的影响，构建出声速-煤温映射关系模型；常温下声波在松散煤体准多孔介质中的传播路径主要受煤样颗粒间孔隙的影响，在煤样粒径为0.6～1.5、1～3、3～5 cm中的声波传输等效路径转换因子$ lambda $分别为1.426 1、1.371 1、1.315 2，与粒径呈负相关关系；煤温对声波传播的影响表现为煤自燃进程中气体组分 介质变化对实测声速结果的改变，验证了声速与煤温之间映射关系的可行性；模型反演的煤温与实验煤温间误差率在0～6.46%内，平均煤温误差2.52 ℃，能够很好地反映煤体温度。

The accurate determination of coal temperature in the hidden spaces such as goaf has always been a worldwide problem that needs to be solved urgently. The study of acoustic temperature measurement technology is of great practical significance for a fast and accurate detection of loose coal temperature, and the scientific and accurate construction of the mapping relationship between sound velocity and coal temperature is the key to acoustic coal temperature measurement. In this paper, considering the influence of the characteristic parameters of spontaneous combustion process of loose coal on sound wave propagation, a mapping model of sound velocity and coal temperature in the quasi-porous media of loose coal was established. An acoustic temperature measurement experimental system for loose coal was designed and built. By conducting the acoustic temperature measurement tests for the loose coal with various particle sizes (0.6～1.5, 1～3, 3～5 cm), the effect of gas composition and concentration on sound propagation during the low-temperature oxidation stage (30～50 ℃) of coal samples with different particle sizes was studied, and the equivalent path conversion factor λ was determined. Based on the relationship between the measured sound velocity and the equivalent path conversion factor, the medium correction coefficient φ of the gas component was proposed and determined, and the feasibility of the sound-temperature mapping relationship model was verified. The results show that the acoustic wave propagation path of loose coal is affected by the characteristic parameters of coal particle size, temperature and the change of gas component medium, etc. A mapping model of sound velocity and coal temperature was established. At normal temperature, the propagation path of sound waves in the quasi-porous medium of loose coal is mainly affected by the pores between the coal particles. The equivalent path conversion factor λ of sound waves is 1.426 1, 1.371 1 and 1.315 2, respectively, when the coal particle size is 0.6～1.5, 1～3, 3～5 cm, which is negatively correlated with the particle size. The influence of coal temperature on acoustic wave propagation is manifested by the change of gas component medium in the process of spontaneous combustion of coal, which verifies the feasibility of the mapping relationship between sound velocity and coal temperature. The error rate between the inversion model and the experimental coal temperature is 0～6.46%, and the average coal temperature error is 2.52 ℃, which can reflect the coal body temperature well.