Research Of Liquid Air Energy Storage System With Single-stage Cold Recovery Structure

Global warming and environmental pollution have become the existential challenges that people have to face in the 21 st century.The sustainable development of human beings can only be realized by vigorously developing renewable energy represented by wind and solar energy.However,the intermittency and instability of renewable energy requires large-scale,long-term storage technologies to match energy supply and demand.Liquid air energy storage(LAES)technology is one of the most promising large-scale and long-term energy storage technologies,which can effectively solve the constraints of renewable energy generation and become more and more popular in the decarbonization of power grid.When electricity is needed,liquid air is vaporized and expanded to generate electricity,and the cold energy generated by liquid air evaporation is stored and recovered for cooling the highpressure air during air liquefaction.Firstly,this dissertation introduces the research background,from the importance of energy storage technology in liquid air energy storage(LAES)technology,through to the LAES literature review summarizes the current research blank and needs to solve the problem.Steadystate model simulation calculation is mainly used in relevant literatures.There are few dynamic models about the operation of the LAES system,especially the unified dynamic model describing the whole process from energy charging,energy storage to energy release of packed bed.In this dissertation,the mathematical model required for the LAES system simulation is systematically established,including the mathematical model of key components,system thermodynamic evaluation model and system economic evaluation model.The model verification is carried out.Secondly,in view of the two-stage structure led to the LAES system is more and more complex,equipment operation control difficulty is high,the cost of investment has increased,take up more space,this dissertation introduces the proposed single-stage compact LAES system structure and two-stage baseline LAES system respectively.Based on the thermodynamic and economic analysis of the LAES system with single working medium and single-stage cold storage,it is compared with the LAES system with baseline two-stage cold storage,and the advantages,disadvantages and conclusions are extracted.Thirdly,the packed bed with stone particles as filler has the advantages of low investment cost,high safety and stability,and its application in energy storage is a hot spot in recent years,with a good industrial application prospect.At present,there are few researches and experiments on the LAES system with packed bed single-stage cold storage.What kind of heat transfer fluid is most suitable for the cold storage packed bed needs to be studied.To solve this problem,the LAES system with packed bed single-stage cold storage is proposed in this dissertation.Different kinds of cold storage media are investigated and screened,and the most suitable single-stage heat transfer medium for cold storage is air.The variable sensitivity analysis of the heat transfer medium is carried out to explore the most appropriate cold storage pressure.Theoretical thermodynamic analysis of the system was carried out without the interference of packed bed.Finally,the research on the influence of cold storage packed bed on the overall operation of the LAES system is not thorough enough,especially the dynamic characteristics from system start-up to stable operation have not been revealed.At present,LAES research is mainly based on simulation analysis,and there are few LAES related experiments,which is not conducive to the future development and application of the LAES.Based on this,this dissertation conducted research screening and characterization experiments on cold storage materials,and used experimental data for theoretical simulation.The dynamic characteristics of cold packed bed at experimental scale were studied and its influence on system efficiency was illustrated.The research results of this dissertation will provide guidance and prediction for the experimental work of the LAES,and ultimately promote the industrial application of LAES technology.