压缩空气储能人工硐库热力耦合解析方法研究

Analytical methods for thermo-mechanical coupling of artificial caverns of the compressed air energy storage

压缩空气储能人工硐库在充气和抽气循环过程中,空气温度、压力,以及硐壁密封层、混凝土衬砌和围岩的温度、应力和应变一直处于变化之中。联合求解这些变量是工程设计中的关键技术,也是理论分析的难点。在一维热传导基本解和人工硐库空气温度基本解的基础上,基于硐壁对流换热和热传导能量守恒,提出人工硐库内空气热力学计算与硐壁热传导的耦合解析方法。与数值模拟结果进行了对比,验证了所提方法的正确性。对一个钢质密封层人工硐库实例进行了分析。结果表明,充抽气过程引起硐库内空气温度的剧烈变化,空气压力变幅明显大于基于恒温假定得到的压力变化结果。硐壁温度周期波动影响深度有限,当混凝土衬砌厚度大于周期波动影响范围后,围岩温度以持续升高直至稳定为特征,围岩强度和稳定性分析可以不考虑周期循环温度的影响。密封层受温度和空气内压双重作用明显,密封层设计需考虑材料的热机械疲劳问题。混凝土衬砌内外表面环向应力和法向应变特征差异巨大,不同工况下内外表面环向应力可能接近混凝土材料的抗压和抗拉强度,混凝土材料的抗压和抗拉强度同为设计的控制因素。混凝土衬砌可以减小围岩压力,但作用有限。在适当的埋深条件下,选择适当的充气压力,可以保证围岩处于弹性状态。

The air temperature,pressure,as well as the temperature,stress,and strain of the sealing layer,concrete liner,and surrounding rock in the compressed air energy storage artificial cavern undergo variations during the inflation and extraction cycles.Jointly solving these variables is a key technique in engineering design and a difficulty in theoretical analysis.This article proposes a coupling calculation method between the thermodynamic of air inside the artificial cavern and the thermal conduction of the cavern wall,based on the one-dimensional basic solution of heat conduction and the basic solution of air temperature in the artificial cavern.The validity of the methodology was confirmed through a rigorous comparison with numerical simulation outcomes.An illustrative case study of a steel-sealed cavern was conducted.The findings reveal that the process of inflating and extracting air within the cavern leads to a substantial variation in air temperature,with the amplitude of pressure fluctuations exceeding those predicted under the assumption of constant temperature.The depth of the tunnel wall is minimally affected by periodic temperature fluctuations.Once the thickness of the concrete lining surpasses the influence range of periodic temperature fluctuations,the temperature of the adjacent rock mass gradually increases until it reaches a stable state.The analysis of the strength and stability of the surrounding rock can be proceed without considering the influence of periodic temperature fluctuations.The sealing layer is significantly affected by the dual effects of temperature and air internal pressure,necessitating the consideration of thermal-mechanical fatigue in its design.The characteristics of hoop stress and radial strain exhibit notable disparities between the inner and outer surfaces of concrete lining.Depending on the working conditions,the hoop stress on the inner and outer surfaces may approach the compressive and tensile strengths of concrete,both of which are crucial design considerations.Concrete lining mitigates the pressure of surrounding rock,albeit with limited effectiveness.At an appropriate burial depth,selecting the appropriate inflation pressure ensures that the surrounding rock remains in an elastic state.