page_title: Thermodynamic cycle
section_title: Each point in the cycle
hierarchical_section_title: Thermodynamic cycle / Heat and work / Each point in the cycle
caption_attribution_description: By Richard Wheeler (Zephyris) 2007. The stirling en:thermodynamic cycle. Related images: en:image:Stirling Cycle.png en:image:Stirling Cycle 1.png en:image:Stirling Cycle 2.png en:image:Stirling Cycle 2a.png en:image:Stirling Cycle 3.png en:image:Stirling Cycle 4.png en:image:Stirling Cycle 4a.png
context_page_description: A thermodynamic cycle consists of a linked sequence of thermodynamic processes that involve transfer of heat and work into and out of the system, while varying pressure, temperature, and other state variables within the system, and that eventually returns the system to its initial state. In the process of passing through a cycle, the working fluid may convert heat from a warm source into useful work, and dispose of the remaining heat to a cold sink, thereby acting as a heat engine. Conversely, the cycle may be reversed and use work to move heat from a cold source and transfer it to a warm sink thereby acting as a heat pump. At every point in the cycle, the system is in thermodynamic equilibrium, so the cycle is reversible.
  During a closed cycle, the system returns to its original thermodynamic state of temperature and pressure. Process quantities, such as heat and work are process dependent. For a cycle for which the system returns to its initial state the first law of thermodynamics applies:
  The above states that there is no change of the energy of the system over the cycle.
context_section_description: Otto Cycle
  1→2: Isentropic expansion: Constant entropy (s), Decrease in pressure (P), Increase in volume (v), Decrease in temperature (T)
  2→3: Isochoric cooling: Constant volume(v), Decrease in pressure (P), Decrease in entropy (S), Decrease in temperature (T)
  3→4: Isentropic compression: Constant entropy (s), Increase in pressure (P), Decrease in volume (v), Increase in temperature (T)
  4→1: Isochoric heating: Constant volume (v), Increase in pressure (P), Increase in entropy (S), Increase in temperature (T)
caption: Description of each point in the thermodynamic cycles.
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