为探明静水压力补偿恒压隧洞式储气库的热力学状态演化规律，采用理论分析方法展开系统性的热力学过程研究，建立绝热、等温与对流换热3种热力学模型，用于描述储气库内空气状态的变化过程。推导绝热模型求解的解析表达式以及等温模型和对流换热模型的差分求解公式，给出圆形与城门洞形储气库换热面积的计算方法，并通过算例分析3种模型下储气库内的温度、体积、㶲值和质量变化过程。算例分析结果表明： 1）在充、放气过程中，恒压隧洞式储气库内压缩空气的平均温度变化幅度较小，其数值始终介于储气库内空气初始温度与充入气体温度之间。2）储气库内空气体积与㶲值均呈近似线性变化趋势；3种热力学模型中，等温模型计算得到的㶲值最大（2.23×10⁶ MJ），绝热模型计算得到的〖㶲值最小（2.11×10⁶ MJ），对流换热模型计算得到的㶲值介于两者之间（2.17×10⁶ MJ）。3）等温模型计算得到的空气质量最多（6.47×10⁶ kg），绝热模型计算得到的空气质量最少（6.11×10⁶ kg），对流换热模型计算得到的空气质量介于两者之间（6.29×10⁶ kg），3种模型条件下的空气质量大小与㶲值大小关系完全对应。

To investigate the evolution patterns of thermodynamic processes within a hydraulic-compensated isobaric tunnel-type compressed air energy storage (CAES) cavern, a systematic study is conducted via theoretical analysis. Three thermodynamic models, including the adiabatic, isothermal, and convective heat transfer models, accounting for the dynamic variation in the heat exchange area during CAES cavern operation across different cross sections are established to describe changes in the air state in gas storage. Analytical solutions are derived for the adiabatic model, and finite-difference formulations are established for the isothermal and convective heat transfer models. Formulas for calculating the heat transfer area are also provided for circular and gateshaped tunnel-type caverns. Finally, the temperature, pressure, exergy, and air mass variations for all three models are analyzed through a case study. The results demonstrate the following: (1) During charging and discharging, the average temperature of compressed air in the isobaric tunnel-type cavern fluctuates minimally, remaining between the initial cavern air temperature and injected air temperature. (2) The air volume and exergy within the cavern exhibit approximately linear variations. Among the three models, the isothermal model yields the highest exergy values (2.23×10⁶ MJ), whereas the adiabatic model produces the lowest (2.11×10⁶ MJ). The exergy values of the convective heat transfer model fall between these two extremes (2.17×10⁶ MJ). (3) The isothermal model stores the greatest air mass (6.47×10⁶ kg), the adiabatic model stores the least (6.11×10⁶ kg), and the value of the convective heat transfer model lies between them (6.29×10⁶ kg). The relationship between air mass and exergy exhibits the same trend across all three models.