| The increasing scarcity of traditional fossil fuels has promoted the rapid development of new energy technologies in the whole world.However,wind and solar energy power generation have the characteristics of volatility and intermittent which is limited by the natural conditions,and its large-scale grid-connection has an adverse impact on the security of the power grid.Therefore,researching and developing the efficient energy storage system,which can achieve the rapid switching of charging and discharging status,and ensure the security and stability of the grid connected system has become the key to the development of renewable energy.Compressed air energy storage system is a kind of large scale energy storage technology.The traditional compressed air energy storage power station has been commercialized,but it has the disadvantages of low energy storage efficiency and fossil fuel consumption.Therefore the green and efficient advanced adiabatic compressed air energy storage system is proposed with the development of energy storage technology.The heat generated in the air compression process is absorbed by the system,so it is free from the dependence on natural gas and avoids the emission of carbon dioxide.But the technology is not mature,and there are still many gaps in the research of the system and equipment.Even so,advanced adiabatic compressed air energy storage technology is considered to be one of the most promising energy storage technologies.In order to deeply analyze the operating performance of the system,the thermodynamic model of the main components such as compressor,gas storage room,expansion machine and thermal storage system is established in this paper.Further more,the thermodynamic characteristics of the system in circulation process are obtained by solving the combined solution,and then the effect of the components on the energy storage system is analyzed.The main research contents are as follows:(1)Establishing the thermodynamic model of polytropic efficiency compressor.Considering the variation of the compressor's polytropic efficiency in the running process,the compressor polytropic efficiency formula is obtained by fitting the compressor performance curve.Based on the fitting formula of compressor polytropic efficiency,comparative analysis has been conducted between the two kinds of energy storage models of constant pressure ratio and swing pressure ratio in the point of compressor power consumption and energy storage stage efficiency.At the same time,the operating characteristics of the system under varying conditions are studied,and the influence of the gas storage condition on the energy storage efficiency and the energy storage density is analyzed.And then the appropriate compressor operation strategy is made.(2)Improving the thermodynamic model of the thermal storage system.Analysing the efficiency change of the heat exchanger in the energy storage stage and energy release stage and studying the effects of different thermophysical properties on heat exchanger efficiency.On the basis of this,the improvement of thermodynamic model of regenerative system is put forward.Under the improved thermodynamic model of thermal storage system,the operation characteristics of the system with water,THERMINOL D12 and THERMINOL 66 are studied.(3)Establishing a thermodynamic model of gas storage room with constant wall temperature.Based on the first law of thermodynamics and the ideal gas state equation,a more practical constant wall temperature gas storage model is proposed.Then the change of air temperature,pressure,and heat transfer in the gas storage room is explored,and the influence of the characteristics of the gas storage chamber on the system is analyzed.Comparing the advantages and disadvantages of various gas storage models,the model of constant temperature and heat insulation gas storage device with better comprehensive performance is designed. |
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