Hampson-Linde cycle
The Hampson–Linde cycle is used in the liquefaction of gases, especially for air separation. William Hampson and Carl von Linde independently filed for patent of the cycle in 1895.
Hampson-Linde systems introduced regenerative cooling, a positive-feedback cooling system. The heat exchanger arrangement permits an absolute temperature difference (e.g. 0.27 °C/atm J-T cooling for air) to go beyond a single stage of cooling, and reach the low temperatures required to liquefy "fixed" gasses.
The Hampson-Linde cycle differs from the Siemens cycle only in the expansion step. Where the Siemens cycle has the gas do external work to reduce its temperature, the Hampson-Linde cycle relies solely on the Joule-Thomson effect. This has the advantage that the cold side needs no moving parts.
In each cycle the net cooling is more than the heat added at the beginning of the cycle. As the gas passes more cycles and becomes cooler, reaching lower temperatures at the expanding cylinder becomes more difficult.
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