| Energy storage technology can solve the imbalance of energy supply and demand in time and space,which plays an important role in improving energy efficiency,saving fossil resources and realizing green and sustainable economic development.Transcritical carbon dioxide energy storage technology is a new type of energy storage technology,which has been deeply studied by many experts and scholars because of the excellent characteristics of carbon dioxide in different states.The heat storage tank is an indispensable main equipment in the transcritical carbon dioxide energy storage system.It is its storage function that realizes the adjustment and control of energy in different time and space.The thermal storage tank of transcritical carbon dioxide energy storage system is taken as the main research object in this paper.And the traditional cold tank and hot tank storage methods are improved.The new way of heat storage and release makes the cold tank initially used to store liquid carbon dioxide be able to help to store part of supercritical carbon dioxide,to a certain extent reducing the investment cost in high-pressure resistant materials and land occupation.Through the simulation of FLUENT software,the heat storage and release characteristics of the improved heat storage tank are obtained,which provides theoretical support for the future optimization research and practical engineering application of the energy storage system.It has certain theoretical help and practical application value to save energy,reduce pollutant emission,solve cogeneration,cut peak and fill valley,etc.Firstly,the physical properties of carbon dioxide were introduced,and the improvement scheme of heat storage tank based on transcritical carbon dioxide energy storage system was described in detail.A model of supercritical carbon dioxide storage tank assisted by cold tank was proposed.The working principle and main equipment of the heat storage tank were analyzed.The application prospect of the tank matching transcritical carbon dioxide energy storage system in power production was discussed.Then the mathematical model of the heat storage tank was established.And the geometric model was built by CAD.The heat storage and release process of the heat storage tank was simulated by FLUENT software.The temperature distribution diagram,velocity distribution diagram and outlet temperature data in different time were obtained.It was found that the distribution of temperature field and velocity field is chaotic in the early and later stages of the heat storage and release process.The fluid mainly flows along the vertical direction,and only moves horizontally at the top,bottom and the obstacles.The thermocline is more stable in the middle stage.Influenced by the boundary layer,the thermocline is thick in the middle and thin near the tank wall,and the whole thermocline gradually thickens with time.The heat storage efficiency is 75.95% and the heat release efficiency is 77.92% under the simulated condition.The heat release efficiency is relatively higher.Furthermore,based on the theory of control variables,we took the heat storage process as an example to explore the factors affecting the heat storage efficiency and a total of 16 groups of data were obtained.The results show that,the number of holes,the size of the holes,the aspect ratio of the tank,the velocity of the inlet and the temperature difference all have great influence on the heat storage efficiency,the heat storage rate and the thickness of the transition layer.Finally,by observing and analyzing the outlet temperature curve,the working structure of the regenerator is optimized once again.Taking the original working condition as an example to Simulated the heat storage process by taking the original working condition as an example,the heat storage efficiency is 80%,increased 5.06%,and the heat storage perform good.If all kinds of influencing factors are adjusted at the same time according to the actual site conditions,the heat storage efficiency will be greatly improved,which can meet the actual heat storage requirements and has certain application value. |
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