Reversible and Irreversibilities
- A reversible process means there are no irreversibilities exist when a system is undergoing interaction with its surroundings. Therefore, the process can be reversed without leaving any trace on its surroundings. Both system and the surroundings are returned to their initial states. It is an ideal process that can not happen in reality. However, if the irreversibilities are small enough, some processes can be approximated as reversible. Ex: a frictionless pendulum, quasi-equilibrium expansion and compression of gas in a cylinder/piston assembly (in an idealized Carnot cycle)
- Irreversibilities: friction, sudden expansion and compression, heat transfer between two bodies with finite temperature difference.