Analytical approach for entropy generation during a laser-pulse heating process

Laser-pulse heating of engineering surfaces finds application in the metal industries. In general, energy-efficient processing depends on the workpiece and laser-pulse properties. Consequently, investigation into entropy generation during the heating and cooling cycles of the process becomes fruitful. In the present study, analytical solutions for temperature distribution and entropy generation inside the substrate material are presented. Temperature distribution and entropy generation resulting from two different pulses having the same energy content, but different pulse lengths, are computed. The entropy number ratio (ratio of entropy generation number in the heating cycle to entropy generation number in the cooling cycle) is obtained. It is found that entropy generated in the surface region of the substrate material is considerably low because of the small temperature gradient in this region. However, the entropy ratio reaches its maximum in this region, which in turn indicates that entropy generation in the heating cycle is considerably higher than its counterpart in the cooling cycle in this region.