*1.3. Boiling on Laser-Texured Surfaces*

Laser texturing is a very effective method for locally or globally changing the morphology of the surface to intensify boiling heat transfer. Može et al. [45] demonstrated a strong enhancement of boiling performance of water on superhydrophobic and superhydrophilic surfaces textured with a nanosecond fiber laser. By combining laser texturing with a superhydrophobic coating, they showed significant improvement in HTC and found that the intensification of boiling heat transfer is possible with a suitable surface morphology where the Wenzel wetting regime is achieved. Kurse et al. [46] studied the pool boiling heat transfer of deionized water on laser-textured surfaces. Microstructures were fabricated on stainless steel using a femtosecond laser. It was found that CHF and the maximum heat transfer coefficient on laser-textured surfaces were improved compared to those on the polished reference surface. It was also found that the improvement of CHF is related to the wetting and wicking capability of the surface, which allows for the replenishing of the evaporating liquid and affects the delay of the CHF. The study of the nucleate pool boiling of water and water-ethanol mixtures on untreated and laser textured stainless steel foils showed a significant improvement in boiling performance on laser-textured surfaces compared to the untreated surfaces for pure liquids and binary mixtures. The improvement in boiling performance is directly related to the microcavities, which act as active nucleation sites [47]. Serdyukov et al. [48] investigated nucleate pool boiling of water on laser textured silicon surfaces. Their results showed an enhancement of the heat transfer coefficient by up to 49.5%, compared to a rough silicon sample, and by up to 234%, compared to a polished sample. Additionally, the study showed that laser texturing of the surfaces resulted in a remarkable increase in the frequency and density of nucleation sites. It was concluded that a decrease in the diameter of the departure bubble and a lower nucleation temperature are characteristics that are associated with the laser-modified silicon surfaces. The study of the stability of copper surfaces before and after functionalization by laser texturing performed with a nanosecond fiber laser was presented by Može et al. [49]. The study showed the enhancement of CHF by up to 90% and HTC by up to 115% on textured surfaces compared to the reference surface. The results also demonstrate the tendency of constant shifts of boiling curves in each experimental run, while the shifts on laser textured surfaces did not occur after the second run. This fact is confirmed by changes in the morphological and chemical structure of the surface after the first onset of CHF and is associated with the effects of low-temperature annealing. Finally, only one study, published by Karthikeyan et al. [50], was found to have previously combined surface laser texturing and the use of nanofluids to enhance boiling heat transfer. The latter authors reported a notable enhancement of boiling heat transfer, but the nanofluid used was rather unconventional (carbon nanotubes dispersed in ethanol or water).
