Retrograde condensation

Retrograde condensation occurs when gas in a tube is compressed beyond the point of condensation with the effect that the liquid evaporates again. This is the opposite of condensation the so called retrograde condensation.

Description

If the volume of two gases which are kept at constant temperature and pressure below critical conditions is gradually reduced, condensation will start. When a certain volume is reached, the amount of condensation will gradually increase upon further reduction in volume until the gases are liquefied. If the composition of the gases lies between their true and pseudo critical points the condensation formed will disappear on continued reduction of volume.^[1][2] The disappearance of condensation is called retrograde condensation.

Because natural gas is not a pure product, when non-associated gas is extracted from a field under supercritical (pressure/temperature) conditions (when the pressure in the reservoir decreases below dewpoint), it may partially condense upon isothermic depressurizing instead of expanding or vaporizing, an effect called retrograde condensation.

Discovery

Johannes Petrus Kuenen discovered retrograde condensation and published his findings in April 1892 with the title "Metingen betreffende het oppervlak van Van der Waals voor mengsels van koolzuur en chloormethyl" (Measurements on the surface of Van der Waals for mixtures of carbonic acid and methyl chloride).^[3][4]

References