| In the face of environmental pollution problems,China began to implement a sustainable development strategy,and increased investment and research and development of green environmental protection projects.Refrigeration as the major energy consumer,and gas compression refrigeration caused environmental problems.Therefore,as a new type of green environmental protection refrigeration technology,room temperature magnetic refrigeration had been received attention,which was friendly to the environment and would not cause greenhouse effect and ozone hole problem.And the Thermodynamic cycle efficiency was high.This paper mainly studies the optimization of the parameters about a new type of composite room temperature magnetic refrigerator.The design research of the new composite room temperature magnetic refrigerator is mainly divided into three parts: performance test of magnetic refrigeration material,influence of operating parameters of magnetic refrigerator on refrigeration performance,and influence of active magnetic regenerator on refrigeration performance.This paper studies and compares the refrigeration performance of magnetic refrigeration materials.The Gd particles with different particle sizes were used to fill the magnetic refrigerator for experiment.Then changed conditions to compare the refrigeration effects.Put the 30~40 mesh and 10~20 mesh Gd particles in the magnetic refrigerators,and it was found that their minimum temperatures of the cold end obtained by loading the magnetic refrigerator for 120 minutes are 1.9 ° C and 6.4 ° C respectively;the different porosity and different mass of the same material have a great influence on the cooling efficiency of the magnetic refrigerator,and the refrigeration cooling effect of the Gd’s particles with a porosity of 0.4 is better than the Gd’s particles with a porosity of 0.45.Increasing the quality of the magnetic medium can significantly improve the cooling effect.This paper studies the effects of the operating parameters of the magnetic refrigerator on the cooling effect,including the four operating parameters of ambient temperature,heat exchange angle,operating cycle and flow.It was found that changing the heat transfer angle had little effect on improving the cooling performance;the ambient temperature had an obvious influence on the magnetic mediums’ magnetocaloric effect,and when the ambient temperature deviated much from the magnetic medium’s Curie temperature,the refrigeration effect was greatly reduced.It was at an appropriate time of the exchange time that can achieve sufficient heat transfer and increase the operating frequency.The shorter the non-heat transfer time,the better the cooling effect.But pay attention to the life of the machine.The active magnetic regenerator is the core component of the magnetic refrigerator.The cooling efficiency of the magnetic refrigerator is improved by the studies on the heat exchange fluid,the shape of the magnetic medium,the superposition of the magnetic medium in different Curie temperature and the structure of the magnetic regenerator.The heat capacity of the heat exchange fluid is larger,the smaller the resistance is,the better the refrigeration efficiency is;the magnetic medium should be made as the shape with a small resistance and large contact area as possibly to effectively improve the heat exchange efficiency;the multi-section superposition of different Curie temperature’s magnetic medium can improve the cooling effect obviously,the minimum temperature of the five-stage superimposed cold end is-0.9 °C.The magnetic medium corresponding to the Curie temperature was filled in the different temperature zones of the temperature gradient,which can make the material of each position of the regenerator exert the maximum magnetic entropy change;the magnetic regenerator of the elongated shape under the same condition has a lower temperature than the cold end of the short and thick shape,and the influence of the shape should be considered on the premise of satisfying the design of the machine. |
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