Isentroopiline

Isentroopiline, or isentropic in English, is a term used in thermodynamics to describe a process, path, or surface in which entropy remains constant. Entropy is a measure of the disorder or the number of microscopic configurations of a system; when a process is isentroopiline, the total entropy does not change as the system evolves.

In thermodynamic theory, an isentroopiline process is associated with reversibility and, for a closed system, with adiabatic conditions (no heat transfer). Specifically, a reversible adiabatic process has dS = δQrev/T = 0, so the entropy S stays constant. Real-world processes are rarely perfectly isentroopiline because irreversibilities or heat exchange introduce entropy production.

For an ideal gas, isentroopiline processes obey specific relations. One common form is pV^γ = constant, where p is pressure, V is volume, and γ = Cp/Cv is the heat capacity ratio. Related forms include TV^(γ−1) = constant and p^(1−γ)T^γ = constant. These relations allow calculation of temperature, pressure, or volume changes during compression or expansion when the process is assumed isentropic.

Isentropics can be depicted as isentropes on state diagrams, representing curves of constant entropy. In engineering, isentropic efficiency compares a real device’s performance to the ideal isentropic process, such as in turbines or compressors. In meteorology, isentropic surfaces are used to analyze atmospheric flows by considering constant potential temperature.

Limitations: true isentroopiline conditions are idealizations. Real fluids exhibit irreversibilities and heat transfer that generate entropy, so practical processes are approximations of isentropic behavior.