Illustration of Joule-Thomson effect

1852 Joule-Thomson effect

The book of science

Tom Sharp

James Prescott Joule, William Thomson, Lord Kelvin thermodynamics Illustration of Joule-Thomson effect

Joule-Thomson effect

James Prescott Joule and his friend Lord Kelvin showed that passing gas through a throttled orifice letting it expand causes it to cool. Specifically, we are not accelerating the gas and we insulate the orifice to avoid exchanging heat.


To move heat from a cold place to a warm place for refrigeration heating and liquifying gases


The energy in a system equal to its internal energy plus the product of pressure and volume measured by the joule.


Throttle valve or porous plug irreversible aperture a passageway that gins up the cycle.

Joule-Thomson expansion converts kinetic energy to potential energy. It does no work. An alternative is a turbine, which in doing work removes energy from the gas.

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