Study of Optimum Structure of Multilayer Type Regenerator with Magnetic Materials by Simulation.

In a 4K regenerative refrigerator, high heat-exchange effectiveness in the regenerator is an important factor for improving the refrigeration capacity. The heat capacity of magnetic regenerative materials in the regenerator must be larger than that of pressurized He gas. However, the heat capacity curve of a single magnetic material is sharper in comparison with that of He gas. To obtain heat capacity comparable with that of He gas over the whole temperature range when the magnetic materials with different peak heat capacity are arranged in multilayers in the regenerator, the regenerative effectiveness, i.e., the heat exchange effectiveness, was calculated by means of a computer. The results clearly showed that a multilayer regenerator is very effective in composing a regenerator capable of covering the specific heat range of He gas. Previous experimental data also indicate that a multilayer regenerator packed with the most suitable regenerative materials can provide a very high refrigeration capacity.