Recent Progress in the Application of Magnetic Regenerator Materials
Various magnetic materials have a large peak in heat capacity C(T) in the vicinity of liquid helium temperature at 7c (magnetic phase transition temperature). However, a single magnetic material is not sufficient for regenerative operations since the peak in C(T) is narrow. Therefore, an important consideration in the development of a magnetic regenerator is the sequencing of the magnetic materials so as to produce the best C(T) distribution. To find out the highest heat exchange effectiveness of a regenerator (regenerator effectiveness), a study was conducted into the effectiveness of multi-layer regenerators composed of several rare-earth compounds with different T C by computer simulation.
The simulation clearly indicated that regenerator effectiveness increases as the number of layers is increased. Among all the different compounds tested, maximum effectiveness was obtained in the case of a two-layer regenerator of Er0.9Yb0.1Ni and Er3Co; a three-layer regenerator of ErNio0.8Co0.2, Er0.9Yb0.1Ni and Er3 Co; and a four-layer regenerator of ErNi0.8Co0.2, Er0.9Yb0.1Ni, ErNi and Er3 Co inserted in sequence from cold to hot.
The refrigeration power of a four-layer regenerator is expected to be twice as much as that of a single-layer Er3Ni.
KeywordsPhase Transition Temperature Magnetic Phase Transition Regenerator Effectiveness Liquid Helium Temperature Regenerative Operation
Unable to display preview. Download preview PDF.
- 2.T. Hashimoto. “Recent progress in magnetic regenerator materials and their application”, Trans, of the JAR 10 (1993) 357Google Scholar
- 3.T. Hashimoto et al. “Excellent character of multi-layer type magnetic regenerator near 4.2K”, Cryocoolers 8 (1995) 677Google Scholar
- 4.H. Seshake et al. “Analysis of rare earth compound regenerators operating at 4K”, Adv. Cryog. Eng. 37B (1997) 995Google Scholar
- 5.T. Hashimoto et al. “Effect of high entropy magnetic regenerator materials on power of the GM refrigerator”, Adv. Cryog. Eng. 40A (1994) 655Google Scholar