Reversible quasi-equilibrium heat transfer is the convection process of (nonzero b and k; a = t = r = 0 or TS = t = r = 0). The spatial and temporal equilibriums are attained at t = r = 0 in (11), but t0 and r0 are nonzero variables. The governing equation for the convection process becomes In the presence of convection and conduction together, we obtain the conventional heat diffusion–convection equation: