The internal source q0 i in Eq. (1) can be identified from Eq. (4). Eq. (4) can be written as where s is the entropy per unit area and unit time. During quasiequilibrium
processes under the assumption that T and s are orthogonal and independent, we find two equations from Eq.Note that these separated equations are possible under the assumption of no radiation contribution in the irreversible nonequilibrium
and quasi-equilibrium regions. Rewriting the above equations, we obtain