摘要 |
A cryogenic refrigeration apparatus comprises an electrically actuated compressor which supplies a working fluid to a free moving displacer which includes a regenerator matrix, so that a container in which the displacer is slidable has a cold end and an ambient temperature end. The matrix comprises a plurality of heat exchange elements which are graded lenthwise of the displacer so as to have larger surface areas adjacent the colder end of the matrix and a reduced flow resistance at the ambient end. The actuator for the compressor is responsive to signals which indicate that the displacer is at the colder end of the container and that the temperature of the colder end is above a pedetermined value.
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