Siemens cycle

Thermodynamics
The classical Carnot heat engine
Branches Classical Statistical Chemical Quantum thermodynamics Equilibrium / Non-equilibrium
Laws Zeroth First Second Third
Systems Closed system Open system Isolated system State Equation of state Ideal gas Real gas State of matter Phase (matter) Equilibrium Control volume Instruments Processes Isobaric Isochoric Isothermal Adiabatic Isentropic Isenthalpic Quasistatic Polytropic Free expansion Reversibility Irreversibility Endoreversibility Cycles Heat engines Heat pumps Thermal efficiency
System properties Note: Conjugate variables in italics Property diagrams Intensive and extensive properties Process functions Work Heat Functions of state Temperature / Entropy (introduction) Pressure / Volume Chemical potential / Particle number Vapor quality Reduced properties
Material properties Property databases Specific heat capacity  ${\displaystyle c=}$ ${\displaystyle T}$ ${\displaystyle \partial S}$ ${\displaystyle N}$ ${\displaystyle \partial T}$ Compressibility  ${\displaystyle \beta =-}$ ${\displaystyle 1}$ ${\displaystyle \partial V}$ ${\displaystyle V}$ ${\displaystyle \partial p}$ Thermal expansion  ${\displaystyle \alpha =}$ ${\displaystyle 1}$ ${\displaystyle \partial V}$ ${\displaystyle V}$ ${\displaystyle \partial T}$
Equations Carnot's theorem Clausius theorem Fundamental relation Ideal gas law Maxwell relations Onsager reciprocal relations Bridgman's equations Table of thermodynamic equations
Potentials Free energy Free entropy Internal energy ${\displaystyle U(S,V)}$ Enthalpy ${\displaystyle H(S,p)=U+pV}$ Helmholtz free energy ${\displaystyle A(T,V)=U-TS}$ Gibbs free energy ${\displaystyle G(T,p)=H-TS}$
History Culture History General Entropy Gas laws "Perpetual motion" machines Philosophy Entropy and time Entropy and life Brownian ratchet Maxwell's demon Heat death paradox Loschmidt's paradox Synergetics Theories Caloric theory Vis viva ("living force") Mechanical equivalent of heat Motive power Key publications An Experimental Enquiry Concerning ... Heat On the Equilibrium of Heterogeneous Substances Reflections on the Motive Power of Fire Timelines Thermodynamics Heat engines Art Education Maxwell's thermodynamic surface Entropy as energy dispersal
Scientists Bernoulli Boltzmann Bridgman Carathéodory Carnot Clapeyron Clausius de Donder Duhem Gibbs von Helmholtz Joule Kelvin Lewis Massieu Maxwell von Mayer Nernst Onsager Planck Rankine Smeaton Stahl Tait Thompson van der Waals Waterston
Other Nucleation Self-assembly Self-organization Order and disorder
Category
v t e

The Siemens cycle is a technique used to cool or liquefy gases.^[1] A gas is compressed, leading to an increase in its temperature due to the directly proportional relationship between temperature and pressure (as stated by Gay-Lussac's law). The compressed gas is then cooled by a heat exchanger and decompressed, resulting in a (possibly condensed) gas that is colder than the original at the same pressure.

Carl Wilhelm Siemens patented the Siemens cycle in 1857.^[2][3]

In the Siemens cycle the gas is:^{[citation needed]}

1. Heated – by compressing the gas – adding external energy into the gas, to give it what is needed for running through the cycle

2. Cooled – by immersing the gas in a cooler environment, losing some of its heat (and energy)

3. Cooled through heat exchanger with returning gas from next (and last stage)

4. Cooled further by expanding the gas and doing work, removing heat (and energy)

The gas which is now at its coolest in the current cycle, is recycled and sent back to be –

5. Heated – when participating as the coolant for stage 3, and then

6. Resent to stage one, to start the next cycle, and be slightly reheated by compression.

In each cycle the net cooling is more than the heat added at the beginning of the cycle. As the gas passes more cycles and becomes cooler, reaching lower temperatures at the expanding cylinder (stage 4 of the Siemens cycle) becomes more difficult.

See also

• Adiabatic process
• Gas compressor
• Hampson–Linde cycle
• Regenerative cooling
• Timeline of low-temperature technology

References

This thermodynamics-related article is a stub. You can help Wikipedia by expanding it.

• v
• t
• e