Three-dimensional laser heating model and entropy generation consideration

Lasers find wide applications in heat treatment of engineering parts. The modeling and energy analysis of the heating process can reduce substantially the time required for process optimization and control. In the present study, three-dimensional laser heating model is introduced using an electron kinetic theory approach, the energy analysis is carried out to predict the first and second law efficiencies, and the entropy generation number is computed during the process. The equation derived for the heat conduction is in the form of an integro-differential equation, which does not yield an analytical solution. Therefore, a numerical method employing an explicit scheme is introduced to discretize the governing heat transfer equation. It is found that the electron lattice site atom collision is the determining process for the internal energy gain of the substrate in the surface vicinity. In addition, the overall entropy generation number computed in the heating cycle is less than what occurs in the cooling cycle of the heat treatment process.