Thermodynamic process
A thermodynamic process (a thermodynamic transformation ) is a change in the thermodynamic state ( change of state ). In the case of a state of equilibrium , this can only happen with a change in one or more external parameters ( state variable ).
In the case of quasi-static thermodynamic processes (equilibrium process), these parameters are changed so slowly that the system is in equilibrium at any point in time (or anywhere near it), i.e. it passes through a sequence of equilibrium states (→ infinitesimally small changes in state ).
Quasi-static processes are called reversible ( reversible in time) if they are reversed by reversing the change in the external parameters themselves. The system and the environment can thus be reset to their original state; the entropy does not increase.
However, when friction is involved, the process can no longer be reversed by reversing the change in external parameters ; Quasi-static processes with friction are therefore irreversible .
Types of thermodynamic processes
Isobaric processes take place at constant pressure. An example can be a movable piston in a cylinder, in which the pressure inside the cylinder is always below atmospheric pressure.
An isochoric process is a process that runs at constant volume. The system does not perform any mechanical work when it is supplied with energy. If a closed system is heated, for example air in a closed can, only the internal energy of the gas is changed, that is, the temperature and pressure increase.
An isothermal process is a process that takes place at a constant temperature. Adiabatic processes are processes without heat supply or removal. Reversible adiabatic processes are identical to isentropic processes, which take place with constant entropy.
From isenthalps processes is when the enthalpy of a system does not change.
Sometimes these processes are also summarized under the term isoprocesses .
Individual evidence
- ^ A b Thermodynamics for mechanical engineers: Basics for practice (Wolfgang Geller, Springer-Verlag, 2015; pages 30 and 31)
- ↑ Technical Thermodynamics, Part 1 (Fran Bosnjakovic, KF Knoche; Springer-Verlag, 2013, page 60)
literature
- Arieh Ben-Naim: Entropy Demystified . World Scientific, 2007, ISBN 981-270-055-2 .
- JS Dugdale: Entropy and its Physical Meaning , 2nd Ed. Edition, Taylor and Francis (UK); CRC (US), 1996, ISBN 0-7484-0569-0 .
- Enrico Fermi , Termodinamica , ed. Italiana Bollati Boringhieri, (1972), ISBN 88-339-5182-0 .
- Enrico Fermi : Thermodynamics . Prentice Hall, 1937, ISBN 0-486-60361-X .
- Herbert Kroemer, Charles Kittel: Thermal Physics , 2nd Ed. Edition, WH Freeman Company, 1980, ISBN 0-7167-1088-9 .
- Roger Penrose : The Road to Reality: A Complete Guide to the Laws of the Universe 2005, ISBN 0-679-45443-8 .
- F. Reif: Fundamentals of statistical and thermal physics . McGraw-Hill, 1965, ISBN 0-07-051800-9 .
- Goldstein, Martin; Inge, F: The Refrigerator and the Universe . Harvard University Press, 1993, ISBN 0-674-75325-9 .
- vonBaeyer; Hans Christian: Maxwell's Demon: Why Warmth Disperses and Time Passes . Random House, 1998, ISBN 0-679-43342-2 .
