Simulation And Analysis Of Hybrid Regenerative And Study On Two Kinds Of Room Temperature Magnetic Refrigerator

In the past thirty years, much attention was paid to magnetic refrigeration near room temperature because of its high efficiency, energy saving and environment being friendly. As two essential factors of a magnetic refrigerator, magnetocaloric materials and magnetic refrigeration system have been widely researched and a large progress has been made, but it still has a long way to run to use the magnetic refrigeration in the real life. In fact, the issues restricting the actual use of magnetic refrigeration require deeper research. Some of the most critical issues are the cooling efficiency, reliability and economy.The present master dissertation will focus on the realization of hybrid regenerative room temperature magnetic refrigerator and the ideal temperature span, give out two different magnetic refrigerator design schemes. The main conclusions are listed as follows:1. The article reviews the history, development and current status of magnetic refrigeration and magnetic refrigeration materials, compares the advantage and disadvantage between magnetic refrigeration and other traditional methods of refrigeration; briefly introduces the basic principles and the realization method, including the theory of magnetocaloric effect, the standard of magnetic material and magnetic field source, finally describes four kinds of cycle means of room temperature magnetic refrigeration and analyzes the advantages and disadvantages of these four cycles. 2. According to the study of magnetic refrigeration, the paper focuses on three different kinds of magnetic refrigeration systems. Numerical calculation of heat transfer between a single Gd piece and fluid, the temperature relationship between Gd piece and fluid was combined. And then two simple programs were proposed to calculate the hybrid regenerative room temperature magnetic refrigeration, one is an ideal heat transfer, that is each coupled Gd pieces transferring heat between hot and cold unit without temperature difference; the other is a little real model, heat transfer of each coupled Gd pieces in hot and cold unit is not sufficient. The result shows that: under the same initial condition, the temperature difference is related to rotating frequency:the more rotating times, the bigger temperature difference. However, the tendency gradually slows down. And result from the second program is not as good as the former one. Therefore, the closer to ideal cycle process has the better cycle performance.3. This paper gives two kinds of designing schemes of room temperature magnetic refrigeration prototypes. In the first scheme, there is a permanent magnet system, magnetic refrigerant box driven with the axis, heat transfer fluid, switching valve system, motors. With magnetic refrigeration material box periodically rotating into the permanent magnet system, the temperature of magnetic refrigeration material rises because of magnetization. The heat transfer fluid from the cold end flows through magnetic refrigeration material, then the heating fluid exchange with the outside heat exchanger. Similarly, removing the magnetic field, the magnetic refrigeration material temperature drops. The heat transfer fluid from hot end and magnetic refrigeration material exchanges heat, which gives the cooling capacity to the cool end. Therefore, magnetic refrigeration is realized. In the second scheme, room temperature magnetic refrigerator which is based on hybrid regenerative contains semicircular permanent magnet system, rotary magnetic material ring, fluid parallel flow pump, heat transfer fluid, motor, workbench, etc. As magnetic material ring rotates, hot end temperature will rise gradually, and the cold end temperature will reduce gradually. Then there is a large temperature span between the hot end and cold end, so that magnetic refrigeration is realized.