The following processes are often used to describe different stages of a thermodynamic cycle:
*Adiabatic : No energy transfer as heat (Q) during that part of the cycle (). Energy transfer is considered as work done by the system only.
*Isothermal : The process is at a constant temperature during that part of the cycle (T=constant, ). Energy transfer is considered as heat removed from or work done by the system.
*Isobaric : Pressure in that part of the cycle will remain constant. (P=constant, ). Energy transfer is considered as heat removed from or work done by the system.
*Isochoric : The process is constant volume (V=constant, ). Energy transfer is considered as heat removed from the system, as the work done by the system is zero.
*Isentropic : The process is one of constant entropy (S=constant, ). It is adiabatic (no heat nor mass exchange) and reversible.
*Isenthalpic : The process that proceeds without any change in enthalpy or specific enthalpy.
*Polytropic : The process that obeys the relation .
*Reversible : The process where the net entropy production is zero; .