The Design And Study On The Cryogenic System Of The MgB₂ Superconducting Motor

Superconducting motor is a high performance motor developed by using superconducting technology and superconducting material. Compared with traditional motor, superconducting motor has a higher efficiency, lower power consumption, smaller volume and lighter quality. So, it has great application market and get much attention. As a new type of superconducting material, the critical temperature of MgB2 is 39K, which is between high temperature superconducting and low temperature superconducting. MgB2 has great feasibility and economy in practical applications. And it has a broad application prospect The cryogenic system is one of the most basic systems of the superconducting motor, and the research objective of this paper is to provide low temperature support for the research of MgB2 superconducting motor.First of all, the cooling mode accords with MgB2 superconducting motor was determined through the comparative analysis of several kinds of cold working fluid as well as the advantages and disadvantages of different cooling mode. A versatile cryogenic system and the overall cooling scheme was established and the cryogenic centrifugal pump in accordance with the requirements of the cryogenic system was designed. Numerical simulation method was used to optimize the design of centrifugal pump, verifiy the theoretical design method of centrifugal fan is suitable for low temperature conditions. Besides, the effect of blade outlet angle on the performance of the centrifugal pump at low temperature, was studied, founds that the centrifugal fan has a higher efficiency when the outlet angel within the angle range of 22°-28° in low temperature condition.Secondly, the cold head heat exchanger and heat exchanger material form--copper block multi-channel cold head heat exchanger was determined, designs and calculates the structure parameters of the cold head heat exchanger. The structural parameters of the cold head heat exchangers are calculated, and the comparison and analysis of many schemes are carried out, and the best design scheme is selected. The heat exchanger was simulated and verified the design rationality by using numerical simulation software. The designed cooling head heat exchanger has good performance.Then, the heat exchange between cryogenic helium and components of the cryogenic system was analyzed and the mathematical model of cooling code and heat transmission process was established. Through the one-dimensional dynamic simulation, getting the temperature distribution when it flows through the parts of the cryogenic system and the temperature change process over time of the parts of the cryogenic system to predict the cooling time of the superconducting motor system.Finally, though the MgB2 superconducting coil cooling experiments, the cooling curve was drawn and the cooling process of superconducting coil was analyzed. The results show that the cryogenic system has a good performance to reduce superconducting coil temperature to working temperature rang. Experimental study finds the problems existed in the cryogenic system. The radiation adiabatic of the system and the temperature distribution of the current leads need to be improved in the follow-up work. It is a good experimental basis for the cooling of MgB2 superconducting motor.