In acoustic temperature measurement, precise determination of sound propagation characteristics is critical for calculating sound propagation velocity. This study investigated the sound wave propagation path in loose coal by assessing the impact of average porosity and temperature on coal particles. Utilizing principles from acoustic temperature measurement and wave equation theory, we propose an equivalent path model for sound wave propagation in quasi-porous media of loose coal. We designed an experimental system and conducted acoustic propagation path tests on loose coal samples with three particle sizes: 0.6–1.5 cm, 1–3 cm and 3–5 cm. Through rigorous analysis, we identified key factors that influence the acoustic propagation path, such as particle size, temperature, and burial depth, which affect the average porosity of the quasi-porous medium. The measured sound velocities for coal samples of 0.6–1.5 cm, 1–3 cm, and 3–5 cm loose coal samples were 238.16 m/s, 252.11 m/s, and 277.36 m/s, respectively. We introduced the equivalent path conversion factor λ for sound wave propagation in loose coal, demonstrating its decrease with larger coal particle sizes. The research validated the accuracy of our equivalent path model, showing a minimal difference between measured and calibrated sound velocities (±4.47 m/s; 4.68% error rate). Our results have theoretical significance for acoustic temperature measurement in the field of loose coal body temperature assessment, offering valuable insights and methods for the advancement of acoustic coal temperature detection technology.

在声学温度测量中，精确确定声音传播特性对于计算声音传播速度至关重要。本研究通过评估平均孔隙率和温度对煤颗粒的影响来研究松散煤中的声波传播路径。利用声学温度测量和波动方程理论的原理，我们提出了松散煤准多孔介质中声波传播的等效路径模型。我们设计了一个实验系统，对0.6~1.5 cm、1~3 cm和3~5 cm三种粒径的松散煤样进行了声波传播路径测试。通过严格的分析，我们确定了影响声波传播路径的关键因素，例如颗粒尺寸、温度和埋藏深度，这些因素影响准多孔介质的平均孔隙率。 0.6~1.5 cm、1~3 cm、3~5 cm松散煤样的实测声速分别为238.16 m/s、252.11 m/s、277.36 m/s。我们引入了松散煤中声波传播的等效路径转换因子λ ，证明其随着煤颗粒尺寸的增大而减小。该研究验证了我们的等效路径模型的准确性，显示测量的声速和校准的声速之间的差异极小（±4.47 m/s；4.68% 错误率）。我们的研究结果对于松散煤体温度评估领域的声学温度测量具有理论意义，为声学煤体温度检测技术的进步提供了有价值的见解和方法。