Is reversible adiabatic process possible? Is it possible to have reversible adiabatic process in practical?
because if it is a reversible process than we allowing it to exchange heat with surroundings. If it is in insulation than  either we some external will conduct process or system will. if system itself itself is doing it than is temperature or  some other thermodynamic parameter may change . Can anyone give me any example?
 A: A process is said to be reversible if the system can be brought back to its initial state without leaving any changes in the surroundings, i.e, the system and the surroundings can be brought back to their initial states. There are no conditions on it concerning the existence of heat exchange, so there is no problem in having an adiabatic or a non adiabatic reversible process (theoretically).
However, in practice, reversible processes themselves are impossible. Just as a frictionless surface in mechanics and a wire with zero resistance in electricity, a reversible process is an ideal case used to simplify problems, but doesn't exist in reality.
A: An example of a reversible adiabatic process is compressing/expanding a gas so rapidly that there is no time for heat transfer to the surroundings, but below the speed of sound so that uneven pressure distributions don't build up in the gas.
The compression/expansion must also be frictionless.
The second law is:
$$ \Delta S = \sum\frac{Q}{T} + S_{gen}$$
If the process is adiabatic (or so fast that negligible heat transfer occurs), then $Q=0$.
If the process is frictionless, then $S_{gen} = 0$.
For a compression, this means $\Delta S=0$, and we could quickly expand after the compression to reach the same state again. It's therefore a reversible process.
