Optimization Design And Heat Transfer Analysis Of Force-cooled Current Leads In Superconducting Magnetic Energy Storage Device Based On Finite Element Method

In superconducting magnetic energy storage, the current lead connects the room-temperature power supply and the low-temperature superconducting magnet. It is the main source of thermal leakage in the system. How to reduce the heat load and refrigeration power has been superconducting technology research hot spot. Traditional current lead analysis method of mathematical model describing ability and the solving method is quite limitations, therefore the optimization theory and method has limit in practical application. Along with the rapid development and maturation of finite element theory, especially the wide application of computer technology, the finite element analysis software provides a good way for analysis of complex nonlinear conditions of physical condition, and also provides a new method and thinking for current lead optimization and analysis. In this thesis, finite element method is used in force-cooled current lead design and heat transfer problem study in superconducting magnets at liquid nitrogen temperature area.Based on analysis of the international current lead research achievements, design scheme of force-cooled current leads in superconducting magnetic energy storage device is made in this thesis. The initial range of current lead length and cross sectional area ratio is calculated with traditional methods, providing range for the analysis model. In electric-thermal coupling analysis, the joule heat, temperature distribution and etc of current lead in self-cooled conditions will be got. Optimization program is executed based on finite element method. The length and cross sectional area ratio of the current lead at minimum heat leakage condition will be got. Under the nitrogen force-cooled condition, the heat transfer problem of the current lead and the nitrogen is analyzed under FLOTRAN software. The temperature distribution of copper wire and nitrogen flow, heat transfer coefficient and pressure will be calculated. The results are helpful to determine the operating parameters of the vacuum pump. Finally current lead analysis results are verified by the experimental.