This paper presents a phenomenological analysis of the relaxation model for
heat conduction and generation from the point of view of its consistency
with the second law of thermodynamics. The formulation of the second law based
on classical irreversible thermodynamics as well as that based on extended
irreversible thermodynamics are considered. It is shown that introduction
of the transient capacity of the heat source into the energy conservation
equation does not lead to any inconsistency with the second law. An analogy
between the heat transport and the motion of a particle in the resistive
medium is presented. The analysis shows that an inherent property of
Cattaneo's model for heat conduction is that heat may flow spontaneously
from cold to hot regions.