Static And Dynamic Thermal Analysis Of Industrial Superconducting Magnet Cooling System

Superconducting magnets are increasingly used in magnetic screening machines and MRI and other industrial and medical equipment.This paper takes the research of superconducting magnets used in superconducting magnetic separator and their cooling systems and conducts theoretical and numerical studies on superconducting magnets and their cooling systems.Determines the static state of superconducting magnets and their cooling systems and dynamic working conditions.The results of the study provide a reference for the design and research of cryogenic cooling systems for small superconducting magnets.The steady state of the superconducting magnet and the cooling system has a direct relationship with the size of the leakage heat from the outside.This article describes the superconducting magnet of the superconducting magnetic separator and the geometric parameters of the cooling system of the superconducting magnetic separator and superconducting magnet cooling system's cooling principle and working process.The quiescent operating point of the superconducting magnet was determined by analyzing the experimental data.The key parameters of the normal working of the cooling system were found.And the working characteristic curve of the cryogenic refrigerator was obtained by studying the small cryogenic refrigerator in the cooling of the superconducting magnet.The static working model of the superconducting magnet cooling system was established,and the program for calculating the static pressure of the liquid helium vessel in the cooling system was written.The change curve of the pressure of the liquid helium vessel with respect to its leakage heat was calculated and the model was combined with the experimental data.Corrected.The calculation program for the relationship between the pressure of the liquid helium vessel and the heat transfer area of the finned heat exchanger was written using the modified liquid helium vessel pressure calculation model.The change curve was calculated and the total heat transfer of the finned heat exchanger was analyzed.The influence of the area on the pressure of the liquid helium vessel provides a reference for the design of the heat exchanger.The static phase distribution and temperature distribution of the fin heat exchanger under low temperature conditions in the liquid helium vessel were calculated by two-dimensional simulation.The influence of the fin pitch on the heat transfer performance of the heat exchanger was further analyzed by changing the fin spacing.The design of the heat exchanger provides a reference.The dynamic change process of the superconducting magnet cooling system is closely related to the heat exchange mode between the liquid helium working substance and each heat leakage surface.The superconducting magnet cooling system was established by studying the conditions and rules of the boiling heat transfer process in liquid helium.In the dynamic model,a dynamic calculation program for the pressure in the liquid helium vessel was written,and the pressure change curve under the stepped heat loss change was calculated and compared with the actual pressure change curve.The superconducting magnet cooling system was analyzed and analyzed.Dynamically changing process control conditions.The core of the stable operation of a superconducting magnet system is that the superconducting magnet coil maintains its temperature below the critical temperature of the superconductor material under the influence of heat leakage and heat loss.In this paper,the superconducting magnet coils cooled by the cooling system are numerically simulated.The steady-state temperature field of superconducting magnet coils and the dynamic temperature field variation process under the heat loss of 0.2J and 2J are given.The analysis results show that the superconducting magnet coils maintain the maximum temperature in the temperature field below 4.85 K under the more severe heat leakage conditions,and the superconducting magnets can be fully cooled without causing quench phenomenon.In the dynamic temperature field distribution of 0.2J heat loss,the maximum temperature is below 4.92 K,which means that the heat loss of the superconducting magnet in the immersion of liquid helium will not increase the temperature of the superconducting magnet before discharge.In the dynamic temperature field distribution of 2J heat loss,the maximum temperature reached 5.5K.The calculation result shows that the superconducting magnet has a lower heat conductivity due to the lower heat conductivity in the order of magnitude of heat loss.Excessive local temperature rise will cause quenching,which in turn will lead to superconductivity of the superconducting magnet.Through analysis,it can be known that the calculation result is due to the fact that the simulation results obtained under the influence of the staggered and twisted structures in the winding of the coil are not taken into account in the change of the convective heat transfer coefficient between the liquid helium and the coil surface,and it can be known in practice that the experiment is performed in an experiment.The superconducting magnets underneath do not produce a total quench.