Retrograde condensation occurs whengas in a tube is compressed beyond the point of condensation with the effect that the liquid evaporates again. This is the opposite ofcondensation: the so-called retrograde condensation.
If the volume of two gases that are kept at constanttemperature andpressure belowcritical 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 pseudocritical points the condensate formed will disappear on continued reduction of volume.[1][2] This disappearance of condensation is called retrograde condensation.
Because mostnatural gas found inpetroleum reservoirs is not a pure product, when non-associated gas is extracted from a field under supercritical pressure/temperature conditions (i.e., the pressure in the reservoir decreases belowdewpoint),condensate liquids may form during theisothermic depressurizing, an effect called retrograde condensation.
Dutch physicistJohannes Kuenen discovered retrograde condensation and published his findings in April 1892 in his Ph.D. thesis with the title "Metingen betreffende het oppervlak van Van der Waals voor mengsels van koolzuur en chloormethyl" (Measurements on theVan der Waals surface for mixtures ofcarbonic acid andmethylchloride).[3][4]