Optimization of Operational Parameters for A 4K-GM Refrigerator

Abstract

This paper describes the experimental results of a 4 K-GM refrigerator, which uses magnetic regenerator materials. The technical point of this study is ascertaining the effects of operational parameters for improving the 4.2 K refrigeration capacity. Compressor capacity and displacer stroke are main parameters in this study. A larger compressor enables a larger refrigeration capacity at a smaller temperature difference in the second regenerator. A smaller compressor, however, is preferable to maintain 4.2 K, when temperature difference is large. Displacer strokes of 12, 20 and 32 mm are investigated. The optimum reciprocating speed for the 4.2 K refrigeration capacity strongly depends on the displacer stroke. The largest refrigeration capacity, however, are almost equal for each of the strokes. In this study, the optimized stroke is found to be 20 mm to obtain refrigeration capacities at the second stage (4.2 K) and the first stage (40 K) simultaneously.