Study On The Design Of Room Temperature Magnetic Refrigerator And The Influence Of Liquid Filling And Heat Exchanger

In recent years,many new and efficient solid-state cooling methods have been promoted due to the increasingly severe environmental problems such as the ozone layer cavity and the greenhouse effect.Among them,as a new green refrigeration technology based on magnetic thermal effect,magnetic refrigeration has attracted wide attention due to its environmental protection,high efficiency and energy conservation.However,there are still many problems to be solved before room-temperature magnetic refrigeration technology can be applied in a truly wide range,such as low refrigerating capacity,small temperature span,large device size and high cost.In order to speed up the application of room-temperature magnetic refrigeration,the design and calculation method of roomtemperature magnetic refrigerating machine are studied in this paper,and the influence of liquid filling quantity and heat exchanger on the performance of room-temperature magnetic refrigerating system is analyzed.First,based on the structure and operation characteristics of the room-temperature magnetic refrigerator,the design method of the room-temperature magnetic refrigerator was studied,and the design and selection of the main components such as the active magnetic regenerator(AMR),heat exchanger,pipeline,valve and fluid pump were carried out.Based on the design method,a room temperature magnetic refrigeration prototype was built,which has the advantages of multi-point measurement,easy control,modularization and convenient liquid exchange,and can meet different experimental requirements.The numerical model of room temperature magnetic refrigeration system is established,and the accuracy of the model is verified.Compared with the conventional numerical model,the model has a complete structure and a high degree of agreement with the experimental results.Finally,the influence of liquid charge and hot and cold end heat exchanger on system performance is studied by using the model.It is found that the liquid filling quantity has a small influence on the temperature span and the cold end temperature of AMR,which mainly affects the stable speed of the system,and the liquid filling quantity has a great influence on the stable period under a small load.The influence of heat exchanger on system performance was explored.It was found that with the increase of heat exchange of the cold end heat exchanger,the temperature span of the steady-state system decreased and the temperature of the AMR cold end increased.With the increase of thermal resistance of the heat exchanger,the temperature span of the steadystate system and the temperature of the cold end of AMR increase.The influence of the heat exchanger on the temperature span of the system is greater at a small flow rate.When the thermal resistance of the hot end is larger and the heat transfer of the cold end is smaller,the temperature span changes more dramatically,and the influence becomes more obvious with the increase of the thermal resistance and the decrease of the heat transfer.Increasing the thermal resistance or decreasing the heat transfer can build a larger temperature span faster.The influence of the heat transfer from the cold end on the temperature of the AMR cold end is greater than that from the thermal resistance of the hot end,and the lower cold end temperature can be obtained faster by reducing the heat transfer from the cold end.Heat exchangers have a greater influence on the temperature changes in the excitation and thermal flow phases.The heat exchanger mainly affects the system performance by affecting the temperature change in the AMR section nearby.In the optimization of hot end heat exchanger,too much pursuit of small thermal resistance has little effect on the change of AMR temperature.