Thermal Analysis And Calculation Optimization For Magnet Of SMES Cooled By Cryocooler

Superconducting Magnetic Energy Storage (SMES) has distinct advantages of the power applications for its high conversion efficiency, rapid responsibility and adjustable voltage frequency. In addition, SMES will be used extensively because it can meet the requirements for computer and electronic equipments, which are sensitive to voltage fluctuation. Cryocooler cooling technology is becoming the development orientation and main research direction of cryogenic system for high temperature superconductor because of its characteristics.According to the National High-tech Development Program (863), Institute of Cryogenics of HUST begins to study and design cooling system of SMES by cryocooler. Based on this background, relevant issues about direct cooling of SMES are discussed in the paper.The thermodynamic analysis of cryocooler-cooled magnet was carried out and the improvement of the cooling method was presented during the comparison of continuous cooling and low temperature end cooling. It was found that the heat should be removed by cryocooler as soon as possible and the heat conduction should be arranged reasonable.Then the concept of effective thermal conductivity of magnet was presented based on the computational model of thermal conductivity of superconducting material. After modeling the magnet, prediction and computation of effective thermal conductivity was accomplished. The optimum designs of operation temperature and structure of magnet was carried out. At the same time several factors that influence the thermal stability of magnet was discussed and improved scheme was put forward.The thermodynamic analysis and optimum designs of cryocooler-cooled binary current leads was presented. The minimum power consumption and the optimum heat intercept point were decided by way of building theoretical model and numerical calculation of binary current leads. The thermal stability of binary current leads was discussed briefly by means of Minimum Quench Energy (MQE).Lastly experiment research was reported on cryocooler cooled magnet made up of Bi-2223/Ag tapes. The descension curve and steady temperature distribution of magnet were achieved. Referenced foundation was put out for practical design of SMES during the comparison of different cooling modes and results.The work of this paper provides theoretical foundation and experimental data for engineering design of cooling systems of SMES cooled by cryocooler.