Joule-Thomson effect

The Joule-Thomson effect describes how a gas's temperature changes when it expands or is forced to pass through a narrow opening, like a valve, without adding or removing heat. In some cases, expanding causes the gas to cool down; in others, it warms up. This temperature change depends on the type of gas and its initial conditions. Engineers use this effect in refrigeration and liquefying gases, as it allows controlled cooling by carefully regulating pressure to achieve desired temperatures without external heat exchange.