Reliquefy

Reliquefy is a verb meaning to return a substance to the liquid state after it has left that state, typically by cooling or compression. In practice, reliquefying refers to re-condensing a gas into a liquid after it has boiled off or vaporized from a stored liquid.

In industrial and scientific contexts, reliquefy is widely used in cryogenics and energy storage. It is especially common in the handling of liquefied gases such as liquefied natural gas (LNG), liquid nitrogen, or liquid helium, where boil-off gas must be returned to liquid form to minimize losses and maintain system pressure.

Technically, reliquefaction uses a refrigeration system or heat exchange equipment to remove latent heat and lower the gas temperature until condensation occurs. Modern plants may employ closed-cycle refrigeration, multi-stage cycles, and expansion devices to improve energy efficiency. The process is integrated with storage tanks, pipelines, and recovery loops to capture and reliquefy vapor as part of a continuous loop.

Spelling: reliquefy is the standard form, derived from re- + liquefy. Some sources use reliquify as an alternate spelling. The term is primarily found in engineering and scientific literature rather than general conversation.

Related concepts include liquefaction, boil-off gas management, LNG storage, and cryogenic refrigeration cycles.