Compressed air is commonly used as power in underground mine .Compressed air adiabatic expansion is often used for heat absorption while it is expanded into surroundings , so it is widely taken as an effective way to im-prove the underground working environment and climate conditions .In order to validate that the isentropic expan-sion principle is better when it is used in high temperature mine or excavating surface cooling , temperature changes of the high pressure gas isentropic expansion and throttling expansion with the pressure and cooling effect were ana -lysed and compared .Through the analysis on influence of mass ratio between compressed air and hot working air to the air quality in underground hot face , some quantitative relationships between mass ratio and air temperature , hu-midity as well as oxygen content in the face after cooling were studied .Meaning while , these quantitative relation-ships were applied to practical case .The effect and economic evaluation of compressed air refrigeration system and the ice cooling system were also discussed .Thus, it showed that the temperature reduction by means of compressed air refrigeration has a better effect and spends less , remains a selective method for deep-well cooling practice in China at present stage .%压缩空气是矿山井下常用动力，压气绝热膨胀能够吸收风流中的热量，因而可用于改善井下作业环境与气候条件。通过理论与实例分析比较高压气体等熵膨胀和节流膨胀温度随压力变化情况及降温效果，得出等熵膨胀原理更适合用于高温矿井或掘进面降温。通过分析压气与引入气流质量比对井下热工作面空气温度、湿度、含氧量的影响，得出压气等熵膨胀降温后矿井气候变化与压气百分比的数学关系式，并将关系式应用于实例中。以矿山具体实例分析了矿井采用压气等熵膨胀制冷后空气质量的变化以及采用压气制冷的成本。同时与冰制冷系统的效果与成本比较，得出选用压气制冷效果好、成本低，可为我国深井局部降温的一种可供选择的方法。
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