How is heat transfer defined in an internally reversible process

Heat transfer for a internally reversible process.

Explanation:

Internally reversible means that there is entropy generation ' with in ' the system.

Heat transfer of a process is considered to be reversible if it occurs because of any minute temperature difference between the surrounding and the system.

Let us consider an example,

Transferring of the heat across the difference in temperature of 0.0001 °C appears as more reversible than for the difference in temperature of 100 °C.

Hence,

By heating or cooling a system for a number of infinitesimally small steps, we can approximate a reversible process.