| 摘要 |
A technique for producing a cold environment wherein warm fluid, e.g. at room temperature, from a compressor, is introduced under pressure into an input channel which is directly coupled to a displacement volume, the fluid being precooled in the input channel to a temperature lower than that of the input fluid. Fluid in the inner channel at or near the displacement volume is periodically pressurized to a high pressure. The displacement volume is then expanded so that the high pressure fluid flowing into the expanded volume is decreased from such high pressure to a substantially lower pressure, the temperature thereof being reduced to a substantially lower temperature for producing the cold environment. The low pressure, low temperature fluid flows into an output channel, preferably via a suitable valve and surge volume, for flow in the output channel at a substantially constant pressure. A direct heat exchange is provided between the input and output channels to provide the precooling of the input fluid and a warming of the fluid in the output channel to a temperature relatively close to, but below, the temperature of the input fluid. The warmed fluid exiting from the output channel is supplied to the compressor when it is compressed for re-introduction into the input channel.
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