| With the development of society and economy,the demand for energy is increasing,human concerns about the depletion of fossil energy and environmental problems caused by fossil energy consumption have led to research on renewable energy development and energy storage systems.As the renewable energy ratio increases,the instability and intermittent nature of renewable energy such as solar energy have an increasing impact on the stability of energy supply networks.Therefore,in order to overcome the problem of instability caused by the intermittent nature of renewable energy and ensure the safe supply of energy,the demand for energy storage systems has become more urgent.The Liquid Air Energy Storage System(LAES)is a new high-density energy storage solution.It is currently a hot spot for the optimization and efficient operation of this energy storage solution.And running it in conjunction with energy systems such as LNG can dramatically increase the efficiency of the entire energy system.This study proposes a novel design of a liquid air energy storage system using LNG cold energy.It is expected to further improve energy efficiency by organically combining LNG with liquid air energy storage systems.In this study,we proposed a liquid air energy storage system that utilizes the cold energy of LNG during air liquefaction.The proposed system case has been modeled and simulated,and relevant data has been obtained.Detailed thermodynamic analysis was performed based on a series of performance indicators to evaluate the feasibility of the proposed system: air-LNG heat exchange efficiency,LNG regasification energy and exergy efficiency,air liquefaction energy and exergy efficiency,energy release energy and exergy efficiency and overall energy and exergy efficiency.The system starts with an air liquefaction process,where air from ambient is being liquefied using four separate stages of compression and five heat exchange in a series combination.After the air is being liquefied,it is stored in cryogenic tanks for energy use during on peak load times.LNG cold energy is utilized in the heat exchangers of the air liquefaction process to cool down the air after each stage of compression.The remaining cold energy of LNG gas is then used to cool the propane in a Rankine cycle to recover part of the remains clod energy in LNG before its being heated to reach its final conditions for distribution.During on peak load times,the stored air is used to generate energy through the air release process.In this process,the air first exchanges heat with propane in another Rankine cycle to recover part of the cold energy of the air,then the air is superheated using an external air heater before it is expanded in the air expander to generate energy.The energy overall efficiency of the system is equals to 56.73% and the exergy efficiency is 71.84%.The results show that LNG regasification cold energy can be effectively utilized by utilizing cold during LNG regasification process,and it can be combined with liquid air storage energy to achieve high-density energy storage while improving energy utilization.The research in this paper has certain reference value for improving the air energy storage system using LNG cold energy. |
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