Thermodynamic analysis and optimization of liquefied air energy storage system

摘要

A large proportion of new energy sources, such as wind and solar energy, are unable to be directly connected to the grid owing to their instability characteristics. To solve this problem, power storage technologies, such as large-scale compressed air energy storage (CAES) technology, have become more important and are playing an increasingly important role. Liquefied air energy storage (LAES) technology is a new type of CAES technology with high power storage density, which can solve the problem of large air storage devices that other CAES systems need to configure. In this study, thermodynamic models of the main components of an LAES system are first established, and the main components of the system are analyzed and optimized. On this basis, the thermodynamic model of an LAES system is established, and the thermodynamic analysis of the system is carried out by means of exergy analysis. The analyzed results show that an LAES system configured with four-stage compression and four-stage expansion has good comprehensive thermodynamic performance. The storage pressure and release pressure of the system are determined to be 15 and 7.1 MPa, respectively, and the air temperature before the pressure reducing valve of liquefaction is 93 K. Increasing the adiabatic efficiency of main components of the LAES system can reduce their exergy loss, thereby reducing the exergy loss of the whole system and improving its energy storage efficiency. (C) 2019 Elsevier Ltd. All rights reserved.