Reliable forecasting of coal seam gas production and gas injectivity(e.g.,CO_(2) or air)requires an accurate understanding of coal’s anisotropic permeability,which governs the directional flow of gas.Although the ani...Reliable forecasting of coal seam gas production and gas injectivity(e.g.,CO_(2) or air)requires an accurate understanding of coal’s anisotropic permeability,which governs the directional flow of gas.Although the anisotropic nature of coal permeability is well recognized,little attention has been paid to how this ratio evolves with changes in effective stress or with the injection of gases that have different affinities to coal.In this work,more than 600 permeability tests were conducted on eight cubic Australian coal samples using He,N_(2) and CO_(2) gases under varying effective stresses,providing a comprehensive dataset that allows the combined effects of effective stress and gas adsorption on permeability anisotropy to be robustly assessed on the same samples.The results demonstrated that all coal samples exhibited evident permeability anisotropy,with ratios ranging from 1.11 to 6.55.For the first time,quantitative relationships between the anisotropy ratio,effective stress,and initial permeability were established for each of the three injection gases,highlighting how gas adsorption and effective stress changes both anisotropic permeability magnitude and ratio.These findings provide new insights into the directional flow behavior of gases in coal seams,with implications for underground compressed air energy storage and CO_(2) sequestration.展开更多
The lined rock cavern(LRC)compressed air energy storage(CAES)system is currently regarded as one of the most promising methods for large-scale energy storage.However,the safety of LRC under high internal pressure has ...The lined rock cavern(LRC)compressed air energy storage(CAES)system is currently regarded as one of the most promising methods for large-scale energy storage.However,the safety of LRC under high internal pressure has emerged as a critical issue that restricts their development.While scholars have focused on the safety of LRC under multiphysics field coupling,few have noticed the inevitable damage sustained by the primary load-bearing components—the surrounding rock and concrete lining—under high internal pressure,compromising their strength and permeation resistance.This study investigates the impact of damage to the surrounding rock and lining concrete on the stability and airtightness of the CAES cavern.First,a damagepermeability evolution model was established by analyzing cyclic loading and unloading test data on concrete samples.Then,a thermo-hydro-mechanical damage(THM-D)coupling model for the CAES cavern was developed and validated against operational data from the Huntorf plant.The coupling responses of both the surrounding rock and lining were compared and analyzed under three different schemes of the first charging and discharging operation.The results revealed the correlation between the air temperature in the cavern and the injection rate and the uneven damage evolution of the surrounding rock and lining caused by the geostress distribution coupled with the heat transfer process.Through the analysis,a higher air injection rate causes more lining damage and air leakage,posing greater risks to engineering safety and airtightness.However,the reduction of inflation time will weaken this effect to some extent.These findings offer valuable insights into the design,construction,and safe operation of LRC compressed air energy storage systems.展开更多
The publisher regrets that the article type for this publication was incorrectly labeled as a Research Article.The correct designation should be Review Article.
Compressed air energy storage(CAES)caverns transformed from horseshoe-shaped roadways in abandoned coal mines still face unclear mechanisms of force transfer,especially in the presence of initial damage in the surroun...Compressed air energy storage(CAES)caverns transformed from horseshoe-shaped roadways in abandoned coal mines still face unclear mechanisms of force transfer,especially in the presence of initial damage in the surrounding rock.The shape and size of the initial damage area as well as their effect on cavern stability remain unclear.Due to the complex geometry and multiphysical couplings,traditional numerical algorithms encounter problems of nonconvergence and low accuracy.These challenges can be addressed through numerical simulations with robust convergence and high accuracy.In this study,the damage area shapes of a CAES cavern are first computed using the concept of damage levels.Then,an iteration algorithm is improved using the generalization a method through the error control and one-way coupling loop for fully coupling equations.Finally,the stability of the CAES cavern with different damage zone shapes is numerically simulated in the thermodynamic process.It is found that this improved algorithm can greatly enhance numerical convergence and accuracy.The nonuniformity of the elastic modulus has a significant impact on the mechanical responses of the CAES cavern.The cavern shape with different damage zones has significant impacts on cavern stability.The initial damage area can delay the responses of temperature and stress.It induces variations of temperature in the range of approximately 1.2 m and variations of stress in the range of 1.5 m from the damage area.展开更多
This paper proposes a detection method based on an improved Mask Region-based Convolutional Neural Network(Mask R-CNN)model for crack recognition in shallow-buried compressed air energy storage(CAES)cavern linings,ena...This paper proposes a detection method based on an improved Mask Region-based Convolutional Neural Network(Mask R-CNN)model for crack recognition in shallow-buried compressed air energy storage(CAES)cavern linings,enabling a comprehensive safety assessment of gas storage caverns.Flexible concrete samples are prepared to simulate the crack characteristics of the sealing lining,providing data support for the recognition module.The Convolutional Block Attention Module is introduced into the ResNet-50 backbone to adaptively adjust feature map weights and enhance feature extraction.Additionally,the mask segmentation loss function is optimized by combining Binary Cross-Entropy loss and Dice loss to improve crack region recognition.Experimental results show that the improved Mask R-CNN model achieves a mean average precision of 89.3%,a 17.2%improvement over the original model,and an intersection over union of 88.41%.Compared to RCNN,Faster R-CNN,YOLOv5,and SSD,the improved model shows superior performance with higher average precision(AP)50:95,AP50,and AP75 values in crack recognition tasks.The proposed method effectively identifies cracks in the flexible concrete sealing lining of shallow-buried CAES caverns,contributing significantly to the prevention of gas storage leaks and providing a valuable approach for the comprehensive safety assessment of CAES gas storage caverns.展开更多
In March 2022,construction was started at Yunlong Lake Laboratory of Deep Underground Science and Engineering,China,on an underground gas storage experimental facility with the capacity to achieve composite structure ...In March 2022,construction was started at Yunlong Lake Laboratory of Deep Underground Science and Engineering,China,on an underground gas storage experimental facility with the capacity to achieve composite structure design and material development.Underground gas storage can provide a solution to address the intermittency of renewable energy supply.Currently,lined rock caverns(LRCs)are regarded as the best option for compressed air and hydrogen storage,since they have excellent sealing properties and minimum environmental impacts.However,the load transfer,damage,and failure mechanisms of LRCs are not clear.This prevents the design and selection of mechanical structures.Particularly,the gas sealing capacity in specific gas conditions(e.g.,stored hydrogen-induced chemical reaction)remains poorly understood,and advanced materials to adapt the storage conditions of different gases should be developed.This experimental facility aims at providing a solution to these technical issues.This facility has several different types of LRCs,and study of the mechanical behavior of various structures and evaluation of the gas-tight performance of the sealing material can be carried out using a distributed fiberoptic sensing approach.The focus of this study is on the challenges in sealing material development and structure design.This facility facilitates large-scale and long-term energy storage for stable and continuous energy supply,and enables repurposing of underground space and acceleration of the realization of green energy ambitions in the context of Paris Agreement and China's carbon neutralization plan.展开更多
Currently,the global energy transition is accelerating,and the large-scale integration of renewable energy has brought many thorny problems to the energy and power systems.In particular,the issues of renewable energy ...Currently,the global energy transition is accelerating,and the large-scale integration of renewable energy has brought many thorny problems to the energy and power systems.In particular,the issues of renewable energy consumption and the difficulty of regulating peak-to-valley differences in the power grid are prominent.Compressed air energy storage,as a new large-scale and long-duration physical energy storage technology,has many advantages such as large scale,long lifespan,low cost,and environmental friendliness.It can solve the problem of difficult grid connection for unstable renewable energy generation such as photovoltaic and wind power,and improve energy utilization.In recent years,the industrialization process has been accelerating,demonstrating huge potential and advantages.This article conducts research and analysis on the industrial logic,technological development,industrialization process,industry competition landscape,and market competitiveness of compressed air energy storage,aiming to provide support for optimizing business layout and structural adjustment of enterprises.展开更多
The paper described a newly developed high performance compressed air foam system(CAFS). The effective system generates uniform foam w ith greater momentum by injecting compressed air into flowing foam solution. Foa ...The paper described a newly developed high performance compressed air foam system(CAFS). The effective system generates uniform foam w ith greater momentum by injecting compressed air into flowing foam solution. Foa m generated by this system presented superior viscous and wetting properties to water.A pendulum system was designed to measure yield stress of foam. The results pro ved the existence of yield stress of foam. And the increasing tendency of yield stress with gas fraction and bubble size has also been found out.展开更多
During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and proper...During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and properly evaluate air tightness of polymer sealing caverns,the air-pressure-related air density and permeability must be considered.In this context,the high-pressure air penetration in the polymer sealing layer is studied in consideration of thermodynamic change of the cavern structure during the system operation.The air tightness model of compressed air storage energy caverns is then established.In the model,the permeability coefficient and air density of sealing layer vary with air pressure,and the effectiveness of the model is verified by field data in two test caverns.Finally,a compressed air storage energy cavern is taken as an example to understand the air tightness.The air leakage rate in the caverns is larger than that using air-pressure-independent permeability coefficient and air density,which is constant and small in the previous leakage rate calculation.Under the operating pressure of 4.5-10 MPa,the daily air leakage in the compressed air storage energy cavern of Yungang Mine with high polymer butyl rubber as the sealing material is 0.62%,which can meet the sealing requirements of compressed air storage energy caverns.The air tightness of the polymer sealing cavern is mainly affected by the cavern operating pressure,injected air temperature,cavern radius,and sealing layer thickness.The cavern air leakage rate will be decreased to reduce the cavern operating pressure the injection air temperature,or the cavern radius and sealing layer thickness will be increased.展开更多
To analyze the working characteristics of complex compressed air networks, numerical methods are widely used which are based on finite element technology or intelligent algorithms. However, the effectiveness of the nu...To analyze the working characteristics of complex compressed air networks, numerical methods are widely used which are based on finite element technology or intelligent algorithms. However, the effectiveness of the numerical methods is limited. In this paper, to provide a new method to optimize the design and the air supply strategy of the complex compressed air pipe network, firstly, a novel method to analyze the topology structure of the compressed air flow in the pipe network is initially proposed. A matrix is used to describe the topology structure of the compressed air flow. Moreover, based on the analysis of the pressure loss of the pipe network, the relationship between the pressure and the flow of the compressed air is derived, and a prediction method of pressure fluctuation and air flow in a segment in a complex pipe network is proposed. Finally, to inspect the effectiveness of the method, an experiment with a complex network is designed. The pressure and the flow of airflow in the network are measured and studied. The results of the study show that, the predicted results with the proposed method have a good consistency with the experimental results, and that verifies the air flow prediction method of the complex pipe network. This research proposes a new method to analyze the compressed air network and a prediction method of pressure fluctuation and air flow in a segment, which can predicate the fluctuation of the pressure according to the flow of compressed air, and predicate the fluctuation of the flow according to the pressure in a segment of a complex pipe network.展开更多
The current research of compressed air engine（CAE） mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popul...The current research of compressed air engine（CAE） mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popularization. In this paper, the working principles of CAE are briefly introduced. To set a foundation for the study on the optimization of the CAE, the basic mathematical model of working processes is set up. A pressure-compensated valve which can reduce the inertia force of the valve is proposed. To verify the mathematical model, the prototype with the newly designed pressure-compensated intake valve is built and the experiment is carried out, simulation and experimental results of the CAE are conducted, and pressures inside the cylinder and output torque of the CAE are obtained. Orthogonal design and grey relation analysis are utilized to optimize structural parameters. The experimental and optimized results show that, first of all, pressure inside the cylinder has the same changing tendency in both simulation curve and experimental curve. Secondly, the highest average output torque is obtained at the highest intake pressure and the lowest rotate speed. Thirdly, the optimization of the single-cylinder CAE can improve the working efficiency from an original 21.95% to 50.1%, an overall increase of 28.15%, and the average output torque increases also increases from 22.047 5 N · m to 22.439 N · m. This research designs a single-cylinder CAE with pressure-compensated intake valve, and proposes a structural parameters design method which improves the single-cylinder CAE performance.展开更多
Compressed air energy storage （CAES） systems represent a new technology for storing very large amount of energy. A peculiarity of the systems is that gas must be stored under a high pressure （p - 10-30 MPa）. A lin...Compressed air energy storage （CAES） systems represent a new technology for storing very large amount of energy. A peculiarity of the systems is that gas must be stored under a high pressure （p - 10-30 MPa）. A lined rock cavern （LRC） in the form of a tunnel or shaft can be used within this pressure range. The rock mass surrounding the opening resists the internal pressure and the lining ensures gas tightness. The present paper investigates the key aspects of technical feasibility of shallow LRC tunnels or shafts under a wide range of geotechnical conditions. Results show that the safety with respect to uplift failure of the rock mass is a necessary but not a sufficient condition for assessing feasibility. The deformation of the rock mass should also be kept sufficiently small to preserve the integrity of the lining and, especially, its tightness. If the rock is not sufficiently stiff, buckling or fatigue failure of the steel lining becomes more decisive when evaluating the feasible operating air pressure. The design of the concrete plug that seals the compressed air stored in the container is another demanding task. Numerical analyses indicate that in most cases, the stability of the rock mass under the plug loading is not a decisive factor for plug design.展开更多
Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a ...Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.展开更多
Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to comp...Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes.This study employs a multi-physical coupling model to compare the operations of CAES and UHS,integrating gas thermodynamics within caverns,thermal conduction,and mechanical deformation around rock caverns.Gas thermodynamic responses are validated using additional simulations and the field test data.Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes.Hydrogen reaches higher temperature and pressure following gas charging stage compared to air,and the ideal gas assumption may lead to overestimation of gas temperature and pressure.Unlike steel lining of CAES,the sealing layer(fibre-reinforced plastic FRP)in UHS is prone to deformation but can effectively mitigates stress in the sealing layer.In CAES,the first principal stress on the surface of the sealing layer and concrete lining is tensile stress,whereas UHS exhibits compressive stress in the same areas.Our present research can provide references for the selection of energy storage methods.展开更多
<div style="text-align:justify;"> With the wide application of renewable energy, energy storage technology has become a research hotspot. In order to overcome the shortcomings of energy loss caused by ...<div style="text-align:justify;"> With the wide application of renewable energy, energy storage technology has become a research hotspot. In order to overcome the shortcomings of energy loss caused by compression heating in compressed air energy storage technology, a novel constant-pressure pumped hydro combined with compressed air energy storage system was proposed. To deepen the understanding of the system and make the analysis closer to reality, this paper adopted an off-design model of the compressor to calculate and analyze the effect of key parameters on system thermodynamics performance. In addition, the results of this paper were compared with previous research results, and it was found that the current efficiency considering the off-design model of compressor was generally 2% - 5% higher than the previous efficiency. With increased preset pressure or with decreased terminal pressure, both the previous efficiency and current efficiency of the system increased. The exergy destruction coefficient of the throttle valve reached 4%. System efficiency was more sensitive to changes in water pump efficiency and hydroturbine efficiency. </div>展开更多
The intermittent nature of wind and solar photovoltaic energy systems leads to the fluctuation of power generated due to the fact that the power output is highly dependent upon local weather conditions, which results ...The intermittent nature of wind and solar photovoltaic energy systems leads to the fluctuation of power generated due to the fact that the power output is highly dependent upon local weather conditions, which results to the load shading issue that led to the voltage and frequency instability. In additional to that, the high proportions of erratic renewable energy sources can lead to erratic frequency changes which affect the grid stability. In order to reduce this effect, the energy storage system is commonly used in most wind-solar energy systems to balance the voltage and frequency instability during load variations. One of the innovative energy storage systems is the compressed air energy storage system (CAES) for wind and solar hybrid energy system and this technology is the key focus in this research study. The aim of this research was to examine the system configuration of the CAES system through modelling and experimental approach with PID controller design for regulating the voltage and frequency under different load conditions. The essential elements and the entire system have been presented in this work as thorough modelling in the MATLAB/Simulink environment for different load conditions. The developed model was tested through an experimental workbench using the developed prototype of the compressed air storage in the Siemens Lab at DeKUT and explored the consequence of the working parameters on the system proficiency and the model accuracy. The performance of the system for the developed prototype of CAES system was validated using results from an experimental workbench with MATLAB/Simulink R2022b simulation. The modeling and experimental results, shows that the frequency fluctuation and voltage drop of the developed CAES system during load variations was governed by the I/P converter using a PID_Compact controller programed in the TIA Portal V17 software and downloaded into PLC S7 1200. Based on these results, the model can be applied as a basis for the performance assessment of the compressed air energy storage system so as to be included in current technology of wind and solar hybrid energy systems.展开更多
The merits of compressed air energy storage(CAES)include large power generation capacity,long service life,and environmental safety.When a CAES plant is switched to the grid-connected mode and participates in grid reg...The merits of compressed air energy storage(CAES)include large power generation capacity,long service life,and environmental safety.When a CAES plant is switched to the grid-connected mode and participates in grid regulation,using the traditional control mode with low accuracy can result in excess grid-connected impulse current and junction voltage.This occurs because the CAES output voltage does not match the frequency,amplitude,and phase of the power grid voltage.Therefore,an adaptive linear active disturbance-rejection control(A-LADRC)strategy was proposed.Based on the LADRC strategy,which is more accurate than the traditional proportional integral controller,the proposed controller is enhanced to allow adaptive adjustment of bandwidth parameters,resulting in improved accuracy and response speed.The problem of large impulse current when CAES is switched to the grid-connected mode is addressed,and the frequency fluctuation is reduced.Finally,the effectiveness of the proposed strategy in reducing the impact of CAES on the grid connection was verified using a hardware-in-the-loop simulation platform.The influence of the k value in the adaptive-adjustment formula on the A-LADRC was analyzed through simulation.The anti-interference performance of the control was verified by increasing and decreasing the load during the presynchronization process.展开更多
The appreciable economic growth in some of the developing countries like India in the recent years, towards providing energy security causes large environmental impact. Renewable Energy （RE） is being seen as one of ...The appreciable economic growth in some of the developing countries like India in the recent years, towards providing energy security causes large environmental impact. Renewable Energy （RE） is being seen as one of the important means to meet the growing power needs of the economy while enhancing energy security and providing opportunities for mitigating greenhouse gas emissions. However, RE sources are highly intermittent in nature. The variability of these sources has led to concerns regarding the reliability of an electric grid that derives a large fraction of its energy from these sources as well as the cost of reliably integrating large amounts of variable generation into the electric grid. Hence at this juncture, it is necessary to explore the benefits of suitable Energy storage technologies. Compressed air energy storage （CAES） is a commercial, utility-scale technology that provides long-duration energy storage with fast ramp rates and good part-load operation. It is a promising storage technology for balancing the large-scale penetration of renewable energies, such as wind and solar power, into electric grids. Considering the potential of CAES storage, the present work, a thermodynamic model is developed with suitable assumptions and the simulation analysis is performed using transient system simulation （TRNSYS） v17 software. The system performanee is compared by considering the recovery during the heat of compression using a thermal storage system and without considering the heat recovery. The overall turnaround efficiency of the system without considering the thermal energy storage （TES） system is 57 % and with TES system the efficiency is increased to 70%.展开更多
The results of struvite reaction crystallization from diluted water solutions of phosphates （V） （0.20 mass% of PO43-） by means of magnesium and ammonium ions are presented. Continuous FB MSZ crystallizer with jet ...The results of struvite reaction crystallization from diluted water solutions of phosphates （V） （0.20 mass% of PO43-） by means of magnesium and ammonium ions are presented. Continuous FB MSZ crystallizer with jet pump driven by compressed air was used. Influence of pH and mean residence time of suspension on the crystal product quality was determined. Increase in pH from 9 to 11 resulted that mean crystal size decreased nearly two-time： from 27.1 to 15.1μm for mean residence time of suspension 900 s. Elongation of this time from 900 to 3,600 s influenced struvite crystal size advantageously-it increased from 27.1 to 41.2 μm at pH 9. From the population density distributions nucleation and growth rates of struvite were calculated based on the simplest SIG model of mass crystallization kinetics in MSMPR crystallizer. Linear growth rate ofstruvite crystals decreased nearly two-time with the increase in environment pH from 9 to 11, and more than 2.5-time with the elongation of mean residence time of crystal suspension in a crystallizer from 900 to 3,600 s from 1.34× 10-8 m/s （pH 9, τ= 900 s） to 2.60×10-9 m/s （pH 11, τ= 3,600 s）.展开更多
Compressed air--a major industrial energy carrier, its filters are used to reach the required cleanliness level of compressed air. These filters, however, introduce a pressure drop which results in a loss of energy. I...Compressed air--a major industrial energy carrier, its filters are used to reach the required cleanliness level of compressed air. These filters, however, introduce a pressure drop which results in a loss of energy. It is shown that over the life cycle of a compressed air filter, the pressure drop dominates the total energy consumption and subsequently, the carbon footprint. From an economic as well as ecologic point of view, a reduction of the pressure drop is hence of utmost importance. Based on this finding and structuring, the wide range of applications and operational parameters, a pragmatic and technically feasible eco-labeling system for compressed air filters was developed as a decision supporting tool. Using this tool, procurement managers as well as the process engineers and environmental officers are able to steer the selection of suitable compressed air filters. The approach has been proposed to and discussed with various representatives of the compressed air filter industry nevertheless there is probably a long way to go to establish such a labeling procedure in industry.展开更多
基金funded by industry members APLNG,Arrow Energy,and Santos through The Gas and Energy Transition Research Centre in The University of Queensland.
文摘Reliable forecasting of coal seam gas production and gas injectivity(e.g.,CO_(2) or air)requires an accurate understanding of coal’s anisotropic permeability,which governs the directional flow of gas.Although the anisotropic nature of coal permeability is well recognized,little attention has been paid to how this ratio evolves with changes in effective stress or with the injection of gases that have different affinities to coal.In this work,more than 600 permeability tests were conducted on eight cubic Australian coal samples using He,N_(2) and CO_(2) gases under varying effective stresses,providing a comprehensive dataset that allows the combined effects of effective stress and gas adsorption on permeability anisotropy to be robustly assessed on the same samples.The results demonstrated that all coal samples exhibited evident permeability anisotropy,with ratios ranging from 1.11 to 6.55.For the first time,quantitative relationships between the anisotropy ratio,effective stress,and initial permeability were established for each of the three injection gases,highlighting how gas adsorption and effective stress changes both anisotropic permeability magnitude and ratio.These findings provide new insights into the directional flow behavior of gases in coal seams,with implications for underground compressed air energy storage and CO_(2) sequestration.
基金National Natural Science Foundation of China,Grant/Award Number:U23B20147Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS),Grant/Award Number:ZDBS-LY-DQC022+1 种基金Hubei Provincial Natural Science Foundation of China,Grant/Award Number:2023AFB346Knowledge Innovation Program of Wuhan-Shuguang Project,Grant/Award Number:2023010201020278。
文摘The lined rock cavern(LRC)compressed air energy storage(CAES)system is currently regarded as one of the most promising methods for large-scale energy storage.However,the safety of LRC under high internal pressure has emerged as a critical issue that restricts their development.While scholars have focused on the safety of LRC under multiphysics field coupling,few have noticed the inevitable damage sustained by the primary load-bearing components—the surrounding rock and concrete lining—under high internal pressure,compromising their strength and permeation resistance.This study investigates the impact of damage to the surrounding rock and lining concrete on the stability and airtightness of the CAES cavern.First,a damagepermeability evolution model was established by analyzing cyclic loading and unloading test data on concrete samples.Then,a thermo-hydro-mechanical damage(THM-D)coupling model for the CAES cavern was developed and validated against operational data from the Huntorf plant.The coupling responses of both the surrounding rock and lining were compared and analyzed under three different schemes of the first charging and discharging operation.The results revealed the correlation between the air temperature in the cavern and the injection rate and the uneven damage evolution of the surrounding rock and lining caused by the geostress distribution coupled with the heat transfer process.Through the analysis,a higher air injection rate causes more lining damage and air leakage,posing greater risks to engineering safety and airtightness.However,the reduction of inflation time will weaken this effect to some extent.These findings offer valuable insights into the design,construction,and safe operation of LRC compressed air energy storage systems.
文摘The publisher regrets that the article type for this publication was incorrectly labeled as a Research Article.The correct designation should be Review Article.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFE0129100National Natural Science Foundation of China,Grant/Award Number:51674246+1 种基金Graduate Innovation Program of China University of Mining and Technology,Grant/Award Number:2023WLJCRCZL046Postgraduate Research&Practice Innovation Program of Jiangsu Province,Grant/Award Number:KYCX23_2660。
文摘Compressed air energy storage(CAES)caverns transformed from horseshoe-shaped roadways in abandoned coal mines still face unclear mechanisms of force transfer,especially in the presence of initial damage in the surrounding rock.The shape and size of the initial damage area as well as their effect on cavern stability remain unclear.Due to the complex geometry and multiphysical couplings,traditional numerical algorithms encounter problems of nonconvergence and low accuracy.These challenges can be addressed through numerical simulations with robust convergence and high accuracy.In this study,the damage area shapes of a CAES cavern are first computed using the concept of damage levels.Then,an iteration algorithm is improved using the generalization a method through the error control and one-way coupling loop for fully coupling equations.Finally,the stability of the CAES cavern with different damage zone shapes is numerically simulated in the thermodynamic process.It is found that this improved algorithm can greatly enhance numerical convergence and accuracy.The nonuniformity of the elastic modulus has a significant impact on the mechanical responses of the CAES cavern.The cavern shape with different damage zones has significant impacts on cavern stability.The initial damage area can delay the responses of temperature and stress.It induces variations of temperature in the range of approximately 1.2 m and variations of stress in the range of 1.5 m from the damage area.
基金the financial supports of the National Natural Science Foundation of China Youth Science Foundation Project(52204152,52204111,52204153)the Postdoctoral Innovation Talent Support Program(BX2020275)the Postdoctoral Science Foundation(2020M683521).
文摘This paper proposes a detection method based on an improved Mask Region-based Convolutional Neural Network(Mask R-CNN)model for crack recognition in shallow-buried compressed air energy storage(CAES)cavern linings,enabling a comprehensive safety assessment of gas storage caverns.Flexible concrete samples are prepared to simulate the crack characteristics of the sealing lining,providing data support for the recognition module.The Convolutional Block Attention Module is introduced into the ResNet-50 backbone to adaptively adjust feature map weights and enhance feature extraction.Additionally,the mask segmentation loss function is optimized by combining Binary Cross-Entropy loss and Dice loss to improve crack region recognition.Experimental results show that the improved Mask R-CNN model achieves a mean average precision of 89.3%,a 17.2%improvement over the original model,and an intersection over union of 88.41%.Compared to RCNN,Faster R-CNN,YOLOv5,and SSD,the improved model shows superior performance with higher average precision(AP)50:95,AP50,and AP75 values in crack recognition tasks.The proposed method effectively identifies cracks in the flexible concrete sealing lining of shallow-buried CAES caverns,contributing significantly to the prevention of gas storage leaks and providing a valuable approach for the comprehensive safety assessment of CAES gas storage caverns.
基金Basic Research Program of Jiangsu Province,Grant/Award Numbers:BK20221135,BK20243024,BM2022009National Key Research and Development Program of China,Grant/Award Number:2022YFC3003300+2 种基金National Natural Science Foundation of China,Grant/Award Numbers:42230704,42307202Young Elite Scientists Sponsorship Program by CAST,Grant/Award Number:2023QNRC001Xuzhou Science and Technology Program,Grant/Award Numbers:KC23383,KC23427。
文摘In March 2022,construction was started at Yunlong Lake Laboratory of Deep Underground Science and Engineering,China,on an underground gas storage experimental facility with the capacity to achieve composite structure design and material development.Underground gas storage can provide a solution to address the intermittency of renewable energy supply.Currently,lined rock caverns(LRCs)are regarded as the best option for compressed air and hydrogen storage,since they have excellent sealing properties and minimum environmental impacts.However,the load transfer,damage,and failure mechanisms of LRCs are not clear.This prevents the design and selection of mechanical structures.Particularly,the gas sealing capacity in specific gas conditions(e.g.,stored hydrogen-induced chemical reaction)remains poorly understood,and advanced materials to adapt the storage conditions of different gases should be developed.This experimental facility aims at providing a solution to these technical issues.This facility has several different types of LRCs,and study of the mechanical behavior of various structures and evaluation of the gas-tight performance of the sealing material can be carried out using a distributed fiberoptic sensing approach.The focus of this study is on the challenges in sealing material development and structure design.This facility facilitates large-scale and long-term energy storage for stable and continuous energy supply,and enables repurposing of underground space and acceleration of the realization of green energy ambitions in the context of Paris Agreement and China's carbon neutralization plan.
文摘Currently,the global energy transition is accelerating,and the large-scale integration of renewable energy has brought many thorny problems to the energy and power systems.In particular,the issues of renewable energy consumption and the difficulty of regulating peak-to-valley differences in the power grid are prominent.Compressed air energy storage,as a new large-scale and long-duration physical energy storage technology,has many advantages such as large scale,long lifespan,low cost,and environmental friendliness.It can solve the problem of difficult grid connection for unstable renewable energy generation such as photovoltaic and wind power,and improve energy utilization.In recent years,the industrialization process has been accelerating,demonstrating huge potential and advantages.This article conducts research and analysis on the industrial logic,technological development,industrialization process,industry competition landscape,and market competitiveness of compressed air energy storage,aiming to provide support for optimizing business layout and structural adjustment of enterprises.
文摘The paper described a newly developed high performance compressed air foam system(CAFS). The effective system generates uniform foam w ith greater momentum by injecting compressed air into flowing foam solution. Foa m generated by this system presented superior viscous and wetting properties to water.A pendulum system was designed to measure yield stress of foam. The results pro ved the existence of yield stress of foam. And the increasing tendency of yield stress with gas fraction and bubble size has also been found out.
基金We acknowledge the funding support from the National Science Foundation of China(Grant No.52278402)the Young Scientist Project of the National Key Research and Development Program of China(Grant No.2021YFC2900600)the Fundamental Research Funds for the Central Universities of China(Grant No.22120220117).
文摘During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and properly evaluate air tightness of polymer sealing caverns,the air-pressure-related air density and permeability must be considered.In this context,the high-pressure air penetration in the polymer sealing layer is studied in consideration of thermodynamic change of the cavern structure during the system operation.The air tightness model of compressed air storage energy caverns is then established.In the model,the permeability coefficient and air density of sealing layer vary with air pressure,and the effectiveness of the model is verified by field data in two test caverns.Finally,a compressed air storage energy cavern is taken as an example to understand the air tightness.The air leakage rate in the caverns is larger than that using air-pressure-independent permeability coefficient and air density,which is constant and small in the previous leakage rate calculation.Under the operating pressure of 4.5-10 MPa,the daily air leakage in the compressed air storage energy cavern of Yungang Mine with high polymer butyl rubber as the sealing material is 0.62%,which can meet the sealing requirements of compressed air storage energy caverns.The air tightness of the polymer sealing cavern is mainly affected by the cavern operating pressure,injected air temperature,cavern radius,and sealing layer thickness.The cavern air leakage rate will be decreased to reduce the cavern operating pressure the injection air temperature,or the cavern radius and sealing layer thickness will be increased.
基金Supported by National Natural Science Foundation of China(Grant No.51205008)
文摘To analyze the working characteristics of complex compressed air networks, numerical methods are widely used which are based on finite element technology or intelligent algorithms. However, the effectiveness of the numerical methods is limited. In this paper, to provide a new method to optimize the design and the air supply strategy of the complex compressed air pipe network, firstly, a novel method to analyze the topology structure of the compressed air flow in the pipe network is initially proposed. A matrix is used to describe the topology structure of the compressed air flow. Moreover, based on the analysis of the pressure loss of the pipe network, the relationship between the pressure and the flow of the compressed air is derived, and a prediction method of pressure fluctuation and air flow in a segment in a complex pipe network is proposed. Finally, to inspect the effectiveness of the method, an experiment with a complex network is designed. The pressure and the flow of airflow in the network are measured and studied. The results of the study show that, the predicted results with the proposed method have a good consistency with the experimental results, and that verifies the air flow prediction method of the complex pipe network. This research proposes a new method to analyze the compressed air network and a prediction method of pressure fluctuation and air flow in a segment, which can predicate the fluctuation of the pressure according to the flow of compressed air, and predicate the fluctuation of the flow according to the pressure in a segment of a complex pipe network.
基金Supported by National Natural Science Foundation of China(Grant Nos.51375028,51205008)
文摘The current research of compressed air engine（CAE） mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popularization. In this paper, the working principles of CAE are briefly introduced. To set a foundation for the study on the optimization of the CAE, the basic mathematical model of working processes is set up. A pressure-compensated valve which can reduce the inertia force of the valve is proposed. To verify the mathematical model, the prototype with the newly designed pressure-compensated intake valve is built and the experiment is carried out, simulation and experimental results of the CAE are conducted, and pressures inside the cylinder and output torque of the CAE are obtained. Orthogonal design and grey relation analysis are utilized to optimize structural parameters. The experimental and optimized results show that, first of all, pressure inside the cylinder has the same changing tendency in both simulation curve and experimental curve. Secondly, the highest average output torque is obtained at the highest intake pressure and the lowest rotate speed. Thirdly, the optimization of the single-cylinder CAE can improve the working efficiency from an original 21.95% to 50.1%, an overall increase of 28.15%, and the average output torque increases also increases from 22.047 5 N · m to 22.439 N · m. This research designs a single-cylinder CAE with pressure-compensated intake valve, and proposes a structural parameters design method which improves the single-cylinder CAE performance.
文摘Compressed air energy storage （CAES） systems represent a new technology for storing very large amount of energy. A peculiarity of the systems is that gas must be stored under a high pressure （p - 10-30 MPa）. A lined rock cavern （LRC） in the form of a tunnel or shaft can be used within this pressure range. The rock mass surrounding the opening resists the internal pressure and the lining ensures gas tightness. The present paper investigates the key aspects of technical feasibility of shallow LRC tunnels or shafts under a wide range of geotechnical conditions. Results show that the safety with respect to uplift failure of the rock mass is a necessary but not a sufficient condition for assessing feasibility. The deformation of the rock mass should also be kept sufficiently small to preserve the integrity of the lining and, especially, its tightness. If the rock is not sufficiently stiff, buckling or fatigue failure of the steel lining becomes more decisive when evaluating the feasible operating air pressure. The design of the concrete plug that seals the compressed air stored in the container is another demanding task. Numerical analyses indicate that in most cases, the stability of the rock mass under the plug loading is not a decisive factor for plug design.
基金supported by the National Natural Science Foundation of China(No.42272321)Hubei Provincial Key Research Projects(Nos.2022BAA093 and 2022BAD163)+1 种基金Major Scientific and Technological Special Project of Jiangxi Province(No.2023ACG01004)WSGRI Engineering&Surveying Incorporation Limited(No.6120230256)。
文摘Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.
基金the financial support from the Natural Science Foundation of China (Nos.52179118,52209151 and 42307238)the Science and Technology Project of Jiangsu Provincial Department of Science and Technology-Carbon Emissions Peak and Carbon Neutrality Science and Technology Innovation Specia Fund Project (No.BK20220025)+3 种基金the Excellent Postdoctoral Program of Jiangsu Province (No.2023ZB602)the China Postdoctora Science Foundation (Nos.2023M733773 and 2023M733772)Xuzhou City Science and Technology Innovation Special Basic Research Plan (KC23045)State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China University of Mining&Technology (No SKLGDUEK1916)。
文摘Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes.This study employs a multi-physical coupling model to compare the operations of CAES and UHS,integrating gas thermodynamics within caverns,thermal conduction,and mechanical deformation around rock caverns.Gas thermodynamic responses are validated using additional simulations and the field test data.Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes.Hydrogen reaches higher temperature and pressure following gas charging stage compared to air,and the ideal gas assumption may lead to overestimation of gas temperature and pressure.Unlike steel lining of CAES,the sealing layer(fibre-reinforced plastic FRP)in UHS is prone to deformation but can effectively mitigates stress in the sealing layer.In CAES,the first principal stress on the surface of the sealing layer and concrete lining is tensile stress,whereas UHS exhibits compressive stress in the same areas.Our present research can provide references for the selection of energy storage methods.
文摘<div style="text-align:justify;"> With the wide application of renewable energy, energy storage technology has become a research hotspot. In order to overcome the shortcomings of energy loss caused by compression heating in compressed air energy storage technology, a novel constant-pressure pumped hydro combined with compressed air energy storage system was proposed. To deepen the understanding of the system and make the analysis closer to reality, this paper adopted an off-design model of the compressor to calculate and analyze the effect of key parameters on system thermodynamics performance. In addition, the results of this paper were compared with previous research results, and it was found that the current efficiency considering the off-design model of compressor was generally 2% - 5% higher than the previous efficiency. With increased preset pressure or with decreased terminal pressure, both the previous efficiency and current efficiency of the system increased. The exergy destruction coefficient of the throttle valve reached 4%. System efficiency was more sensitive to changes in water pump efficiency and hydroturbine efficiency. </div>
文摘The intermittent nature of wind and solar photovoltaic energy systems leads to the fluctuation of power generated due to the fact that the power output is highly dependent upon local weather conditions, which results to the load shading issue that led to the voltage and frequency instability. In additional to that, the high proportions of erratic renewable energy sources can lead to erratic frequency changes which affect the grid stability. In order to reduce this effect, the energy storage system is commonly used in most wind-solar energy systems to balance the voltage and frequency instability during load variations. One of the innovative energy storage systems is the compressed air energy storage system (CAES) for wind and solar hybrid energy system and this technology is the key focus in this research study. The aim of this research was to examine the system configuration of the CAES system through modelling and experimental approach with PID controller design for regulating the voltage and frequency under different load conditions. The essential elements and the entire system have been presented in this work as thorough modelling in the MATLAB/Simulink environment for different load conditions. The developed model was tested through an experimental workbench using the developed prototype of the compressed air storage in the Siemens Lab at DeKUT and explored the consequence of the working parameters on the system proficiency and the model accuracy. The performance of the system for the developed prototype of CAES system was validated using results from an experimental workbench with MATLAB/Simulink R2022b simulation. The modeling and experimental results, shows that the frequency fluctuation and voltage drop of the developed CAES system during load variations was governed by the I/P converter using a PID_Compact controller programed in the TIA Portal V17 software and downloaded into PLC S7 1200. Based on these results, the model can be applied as a basis for the performance assessment of the compressed air energy storage system so as to be included in current technology of wind and solar hybrid energy systems.
基金supported by National Natural Science Foundation of China(Project No.52077079).
文摘The merits of compressed air energy storage(CAES)include large power generation capacity,long service life,and environmental safety.When a CAES plant is switched to the grid-connected mode and participates in grid regulation,using the traditional control mode with low accuracy can result in excess grid-connected impulse current and junction voltage.This occurs because the CAES output voltage does not match the frequency,amplitude,and phase of the power grid voltage.Therefore,an adaptive linear active disturbance-rejection control(A-LADRC)strategy was proposed.Based on the LADRC strategy,which is more accurate than the traditional proportional integral controller,the proposed controller is enhanced to allow adaptive adjustment of bandwidth parameters,resulting in improved accuracy and response speed.The problem of large impulse current when CAES is switched to the grid-connected mode is addressed,and the frequency fluctuation is reduced.Finally,the effectiveness of the proposed strategy in reducing the impact of CAES on the grid connection was verified using a hardware-in-the-loop simulation platform.The influence of the k value in the adaptive-adjustment formula on the A-LADRC was analyzed through simulation.The anti-interference performance of the control was verified by increasing and decreasing the load during the presynchronization process.
文摘The appreciable economic growth in some of the developing countries like India in the recent years, towards providing energy security causes large environmental impact. Renewable Energy （RE） is being seen as one of the important means to meet the growing power needs of the economy while enhancing energy security and providing opportunities for mitigating greenhouse gas emissions. However, RE sources are highly intermittent in nature. The variability of these sources has led to concerns regarding the reliability of an electric grid that derives a large fraction of its energy from these sources as well as the cost of reliably integrating large amounts of variable generation into the electric grid. Hence at this juncture, it is necessary to explore the benefits of suitable Energy storage technologies. Compressed air energy storage （CAES） is a commercial, utility-scale technology that provides long-duration energy storage with fast ramp rates and good part-load operation. It is a promising storage technology for balancing the large-scale penetration of renewable energies, such as wind and solar power, into electric grids. Considering the potential of CAES storage, the present work, a thermodynamic model is developed with suitable assumptions and the simulation analysis is performed using transient system simulation （TRNSYS） v17 software. The system performanee is compared by considering the recovery during the heat of compression using a thermal storage system and without considering the heat recovery. The overall turnaround efficiency of the system without considering the thermal energy storage （TES） system is 57 % and with TES system the efficiency is increased to 70%.
文摘The results of struvite reaction crystallization from diluted water solutions of phosphates （V） （0.20 mass% of PO43-） by means of magnesium and ammonium ions are presented. Continuous FB MSZ crystallizer with jet pump driven by compressed air was used. Influence of pH and mean residence time of suspension on the crystal product quality was determined. Increase in pH from 9 to 11 resulted that mean crystal size decreased nearly two-time： from 27.1 to 15.1μm for mean residence time of suspension 900 s. Elongation of this time from 900 to 3,600 s influenced struvite crystal size advantageously-it increased from 27.1 to 41.2 μm at pH 9. From the population density distributions nucleation and growth rates of struvite were calculated based on the simplest SIG model of mass crystallization kinetics in MSMPR crystallizer. Linear growth rate ofstruvite crystals decreased nearly two-time with the increase in environment pH from 9 to 11, and more than 2.5-time with the elongation of mean residence time of crystal suspension in a crystallizer from 900 to 3,600 s from 1.34× 10-8 m/s （pH 9, τ= 900 s） to 2.60×10-9 m/s （pH 11, τ= 3,600 s）.
文摘Compressed air--a major industrial energy carrier, its filters are used to reach the required cleanliness level of compressed air. These filters, however, introduce a pressure drop which results in a loss of energy. It is shown that over the life cycle of a compressed air filter, the pressure drop dominates the total energy consumption and subsequently, the carbon footprint. From an economic as well as ecologic point of view, a reduction of the pressure drop is hence of utmost importance. Based on this finding and structuring, the wide range of applications and operational parameters, a pragmatic and technically feasible eco-labeling system for compressed air filters was developed as a decision supporting tool. Using this tool, procurement managers as well as the process engineers and environmental officers are able to steer the selection of suitable compressed air filters. The approach has been proposed to and discussed with various representatives of the compressed air filter industry nevertheless there is probably a long way to go to establish such a labeling procedure in industry.
