Temperature–entropy diagram

For other uses, see Tanabe-Sugano diagram.

Branches

Equilibrium / Non-equilibrium

State
Equation of state Ideal gas Real gas State of 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

Functions of state
Property diagrams Intensive and extensive properties
Temperature / Entropy (introduction) Pressure / Volume Chemical potential / Particle number Vapor quality Reduced properties
Process functions
Work Heat

Material properties

Property databases

Specific heat capacity

c=

$T$	$\partial S$
$N$	$\partial T$

Compressibility

\beta=-

$1$	$\partial V$
$V$	$\partial p$

Thermal expansion

\alpha=

$1$	$\partial V$
$V$	$\partial T$

Equations

Potentials

Internal energy
$U(S,V)$
Enthalpy
$H(S,p)=U+pV$
Helmholtz free energy
$A(T,V)=U-TS$
Gibbs free energy
$G(T,p)=H-TS$

History
Culture

History
General Heat 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 Theory of heat 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

Book:Thermodynamics

A temperature entropy diagram, or T-s diagram, is used in thermodynamics to visualize changes to temperature and specific entropy during a thermodynamic process or cycle. 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.^[1]

An isentropic process is depicted as a vertical line on a T-s diagram, whereas an isothermal process is a horizontal line.^[2]

This example T-s diagram shows a thermodynamic cycle taking place between a hot reservoir at temperature T_H and a cold reservoir at temperature T_C. For reversible processes, such as those found in the Carnot cycle, the area in red Q_C is the amount of energy exchanged between the system and the cold reservoir. The area in white W is the amount of work energy exchanged by the system with its surroundings. The amount of heat Q_H exchanged with the hot reservoir is the sum of the two. The thermal efficiency of the cycle is the ratio of the white area (work) divided by the sum of the white and red areas (total heat). If the cycle moves in a clockwise sense then it is a heat engine that outputs work, if the cycle move in a count-clockwise sense it is a heat pump the takes in work and moves heat Q_H from the cold reservoir to the hot reservoir.

T-s diagram for steam, US units.

References

↑ "Temperature Entropy (T-s) Diagram - Thermodynamics - Thermodynamics". Engineers Edge. Retrieved 2010-09-21.
↑ "P-V and T-S Diagrams". Grc.nasa.gov. 2008-07-11. Retrieved 2010-09-21.

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Temperature–entropy diagram

See also

References