{{short description|Graph relating temperature and entropy during a thermodynamic process or cycle}} {{Other uses|Tanabe–Sugano diagram}} {{Thermodynamics sidebar}}
In thermodynamics, a '''temperature–entropy''' ('''''T–s''''') '''diagram''' is a thermodynamic diagram used to visualize changes to temperature ({{mvar|T }}) and specific entropy ({{mvar|s}}) during a thermodynamic process or cycle as the graph of a curve. It is a useful and common tool, particularly because it helps to visualize the heat transfer during a process. For reversible (ideal) processes, the area under the ''T–s'' curve of a process is the heat transferred to the system during that process.<ref>{{cite web|url=https://www.engineersedge.com/thermodynamics/temp_enthalpy_th_diagram.htm |title=Temperature Entropy (''T–s'') Diagram - Thermodynamics - Thermodynamics |publisher=Engineers Edge |date= |accessdate=2010-09-21}}</ref>
Working fluids are often categorized on the basis of the shape of their ''T–s'' diagram.
An isentropic process is depicted as a vertical line on a ''T–s'' diagram, whereas an isothermal process is a horizontal line.<ref>{{cite web|url=https://www.grc.nasa.gov/WWW/K-12/airplane/pvtsplot.html |title=P–V and T–S Diagrams |publisher=Grc.nasa.gov |date=2008-07-11 |accessdate=2010-09-21}}</ref>
[[Image:Ejemplo Diagrama T-S.png|thumb|left|Example ''T–s'' diagram for a thermodynamic cycle taking place between a hot reservoir ({{math|''T''{{sub|H}}}}) and a cold reservoir ({{math|''T''{{sub|C}}}}). <br> For reversible processes, such as those found in the Carnot cycle: {{legend|#e69ca6|{{math|1=''Q''{{sub|C}} =}} the amount of energy exchanged between the system and the cold reservoir}} {{legend|white|{{math|1=''W'' =}} work exchanged by the system with its surroundings}} {{math|1=''Q''{{sub|H}} = ''W'' + ''Q''{{sub|C}} =}} heat exchanged with the hot reservoir. {{math|1=''η'' = ''W'' / ''Q''{{sub|H}} =}} thermal efficiency of the cycle<br> If the cycle moves in a clockwise sense, then it is a heat engine that outputs work; if the cycle moves in a counterclockwise sense, it is a heat pump that takes in work and moves heat {{math|''Q''{{sub|H}}}} from the cold reservoir to the hot reservoir.]]
thumb|T–s diagram for steam, US units {{Clear}} ==See also== *Carnot cycle *Pressure–volume diagram *Rankine cycle *Saturation vapor curve *Working fluid *Working fluid selection
==References== {{Reflist}}
{{DEFAULTSORT:Temperature-entropy diagram}} Category:Thermodynamics
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