Orman Łukasz J, Radek Norbert, Pietraszek Jacek, Wojtkowiak Janusz, Szczepaniak Marcin
Faculty of Environmental, Geomatic and Energy Engineering, Kielce University of Technology, Al. Tysiaclecia P.P. 7, 25-314 Kielce, Poland.
Faculty of Mechatronics and Mechanical Engineering, Kielce University of Technology, Al. Tysiaclecia P.P. 7, 25-314 Kielce, Poland.
Materials (Basel). 2023 Feb 6;16(4):1365. doi: 10.3390/ma16041365.
The laser treatment of surfaces enables the alteration of their morphology and makes them suitable for various applications. This paper discusses the use of a laser beam to develop surface features that enhance pool boiling heat transfer. Two types of structures (in the 'macro' and 'micro' scale) were created on the samples: microfins (grooves) and surface roughness. The impact of the pulse duration and scanning velocity on the height of the microfins and surface roughness at the bottom of the grooves was analyzed with a high precision optical profilometer and microscope. The results indicated that the highest microfins and surface roughness were obtained with a pulse duration of 250 ns and scanning velocity of 200 mm/s. In addition, the influence of the 'macro' and 'micro' scale modifications on the boiling heat transfer of distilled water and ethyl alcohol was studied on horizontal samples heated with an electric heater. The largest enhancement was obtained for the highest microfins and roughest surfaces, especially at small superheats. Heat flux dissipated from the samples containing microfins of 0.4 mm height was, maximally, over three times (for water) and two times (for ethanol) higher than for the samples with smaller microfins (0.2 mm high). Thus, a modification of a selected model of boiling heat transfer was developed so that it would be applicable to laser-processed surfaces. The correlation proved to be quite successful, with almost all experimental data falling within the ±100% agreement bands.
对表面进行激光处理能够改变其形态，使其适用于各种应用。本文讨论了利用激光束形成表面特征以增强池式沸腾传热。在样品上创建了两种类型的结构（“宏观”和“微观”尺度）：微翅片（凹槽）和表面粗糙度。使用高精度光学轮廓仪和显微镜分析了脉冲持续时间和扫描速度对微翅片高度以及凹槽底部表面粗糙度的影响。结果表明，脉冲持续时间为250 ns且扫描速度为200 mm/s时可获得最高的微翅片和表面粗糙度。此外，在用电加热器加热的水平样品上研究了“宏观”和“微观”尺度改性对蒸馏水和乙醇沸腾传热的影响。对于最高的微翅片和最粗糙的表面，尤其是在小过热度下，获得了最大的强化效果。从高度为0.4 mm的含微翅片样品散失的热流，最高比微翅片较小（0.2 mm高）的样品高出三倍多（对于水）和两倍（对于乙醇）。因此，开发了一种选定的沸腾传热模型的修正方法，使其适用于激光加工表面。该相关性被证明相当成功，几乎所有实验数据都落在±100%的一致性范围内。
