Search results
Results from the WOW.Com Content Network
In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect or Kelvin–Joule effect) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is expanding; typically caused by the pressure loss from flow through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment.
In 1895, William Hampson in England [3] and Carl von Linde in Germany [4] independently developed and patented the Hampson–Linde cycle to liquefy air using the Joule–Thomson expansion process and regenerative cooling. [5] On 10 May 1898, James Dewar used regenerative cooling to become the first to statically liquefy hydrogen.
The Hampson–Linde cycle differs from the Siemens cycle only in the expansion step. Whereas the Siemens cycle has the gas do external work to reduce its temperature, the Hampson–Linde cycle relies solely on the Joule–Thomson effect ; this has the advantage that the cold side of the cooling apparatus needs no moving parts.
The Joule–Thomson effect, the temperature change of a gas when it is forced through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment. The Gough–Joule effect or the Gow–Joule effect, which is the tendency of elastomers to contract if heated while they are under tension.
The Joule expansion (a subset of free expansion) is an irreversible process in thermodynamics in which a volume of gas is kept in one side of a thermally isolated container (via a small partition), with the other side of the container being evacuated. The partition between the two parts of the container is then opened, and the gas fills the ...
An expansion tank or expansion vessel is a small tank used to protect closed water heating systems and domestic hot water systems from excessive pressure. The tank is partially filled with air, whose compressibility cushions shock caused by water hammer [ citation needed ] and absorbs excess water pressure caused by thermal expansion .
fluid flow through a flow resistance such as in the Joule expansion or the Joule–Thomson effect; heat transfer; Joule heating; friction between solid surfaces; fluid viscosity within a system. The expression for the rate of entropy production in the first two cases will be derived in separate sections. Fig.2 a: Schematic diagram of a heat engine.
In the case of free expansion for an ideal gas, there are no molecular interactions, and the temperature remains constant. For real gasses, the molecules do interact via attraction or repulsion depending on temperature and pressure, and heating or cooling does occur. This is known as the Joule–Thomson effect.