Three-dimensional thermal-fluid-structure coupling model and stability analysis of hydrogen storage operation in underground lined rock cavern group
Clean and renewable energy is the fundamental way to achieve the goal of"double carbon".Hydrogen storage in underground lined rock caverns is one of the effective means to reduce its volatility and intermittency.Therefore,a three-dimensional thermal-fluid-structure multi-field coupling model of hydrogen storage in lined rock caverns was established based on gas thermal flow equation,turbulence equation,solid heat conduction equation and ther-moelastic mechanics equation,and its effectiveness and superiority were verified.The thermal-fluid-structure coupling model was solved by COMSOL Multiphysics software.And the com-pressible thermal flow characteristics of the gas in the cavern and the thermodynamic response of the lining layer and the surrounding rock during the injection-production process were ana-lyzed.Furthermore,the influences of buried depth,spacing,gas injection temperature and in-jection-production mode on the stability of cavern group are further explored.The results show that the hydrogen temperature and pressure increase with gas injection and decrease with gas production.The temperature distribution in the cavern is uneven,and the temperature differ-ence between the top and the bottom reaches 9.7 K at the end of gas injection.When the two caverns are injected and mined simultaneously,the first principal stress of the surrounding rock and lining layer of the caverns increases with the gas injection,and decreases sharply in the gas extraction stage.At the end of gas injection,the maximum tensile stress,is 3.12 MPa,appearing at the top of the cavern,which is the most prone to tensile failure.The dis-placement of the surrounding rock of the cavern is consistent with the change of the first prin-cipal stress.The maximum displacement of the central area of the side wall of the cavern rea-ches 20.2 mm at the end of the gas injection,and the buried depth has little effect on the dis-placement of the cavern.The larger the spacing between the two caverns,the smaller the stress concentration degree of the middle rock pillar between the caverns,and the safer the whole.When the spacing between the caverns is greater than twice the diameter of the cavern,the stress state of the middle rock pillar is close to the original rock state.When the injection temperature increased from 266.15 K to 306.15 K,the chamber pressure increased by 4.1％at the end of gas injection.One cavern gas storage,the other cavern injection and production is the most dangerous working condition,while one cavern to be stored,the other cavern injec-tion and production is the most safe working condition.In actual operation,the injection and production scheme should be optimized and specific process measures should be taken to main-tain the long-term stability of the hydrogen storage cavern group.The conclusions are expected to provide some reference for engineering practice.
lined rock cavernunderground hydrogen storagethermal-fluid-solid couplingoperation schemestability of cavern group
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