Component Design Optimization And Performance Evaluation For Isothermal Compressed Air Energy Storage Technology

Nowadays, there are only two kinds of energy storage systems whose capacity is large enough for the grid, pumped storage(PS) and compressed air energy storage(CAES). However, CAES plays its unique role. Although adiabatic CAES can solve the traditional CAES’s problem of the requirement of afterburner, severe variation in temperature has a greater impact on efficiency and the device itself. Considering these shortcomings, a new type of CAES-isothermal CAES technologies is proposed.An isothermal CAES device is mainly concerned.Firstly, the technologies of isothermal CAES is introduced. The efficiency of two technologies, isothermal CAES and adiabatic CAES, is compared by p-V diagram. Through the theoretical analysis, the foudation of isothermal CAES is established, which is the theoretical cornerstone of the entire device.On the theoretical basis, the system diagram of isothermal CAES device is presented, and the detail of device and the operating process are described. In the design, the packing tower and plate tower technology is used on the fluid exchange unit, called internal temperature controlled liquid piston. And the internal temperature controlled liquid piston is designed to achieve the isothermal process.In order to tackle the problem that severe variation of pressure have an great influence on efficiency, adaptive hydraulic potential energy conversion device and its corresponding adaptive principle are proposed to achieve maximum efficiency of energy transfer between the two sets of potential energy. Adaptive hydraulic potential energy conversion device is realized by valves under the control of PLC. In addition, elevant electrical accessories and the hardware programme to operate the overall device are demonstrated. And the whole structure of the device and some design of details, such as hydraulic control unit and so on, are introduced.The modeling and simulation of internal temperature controlled liquid piston are finished by FLUENT and its related software. The analysis result verifies that internal temperature controlled liquid piston can achieve isothermal process.The working principle of valves and related contents of PLC are introduced. And the controlling program of valves is designed to get the specific valve’s switch status table, which is the theoretical foundation of valves’control of the isothermal CAES device. Based on adaptive principle, operation results and specific control scheme can be obtained by MATLAB. The efficiency of the device is obtained and the correctness and rationality of the device is proved by analysis of loss and performance evaluation.Finally, it is promising to expand the scale of the experimental device to realize larger scale of storage, and service the actual grid in the future.