表面芯吸性对淬火过程中沸腾传热特性的影响

研究表面芯吸性对淬火过程中的冷却速率和沸腾传热特性的影响.采用质量分数约为50%的氢氟酸溶液对不锈钢球表面进行化学腐蚀，在恒温50℃时通过改变腐蚀时间得到具有不同芯吸性的试样并对表面芯吸量和初始芯吸通量进行定量表征.在常压下的饱和水中对所制备的芯吸表面进行可视化淬火实验.结果表明，原始不锈钢表面不具有芯吸性，随着腐蚀时间的增加表面芯吸能力也逐渐增强.经过腐蚀3 min之后，表面芯吸通量达到20 μL/（mm2·s）.该芯吸表面使淬火冷却时间相较于原始表面缩短约80%，临界热流密度提高了约84%.构建表面芯吸性可以有效地增大固液接触面积并加剧表面汽膜波动，抑制了稳定膜态沸腾的出现，强化了过渡态沸腾传热.
Abstract: The effect of surface wicking on the cooling rate and boiling heat transfer during quenching was analyzed. Stainless steel sphere samples with various surface wicking abilities were prepared by varying the etching time in a hydrofluoric acid solution (mass concentration of about 50%) at a constant temperature of 50℃. The wicking volume and initial wicking flux on these sample surfaces were quantified. Visualized quenching experiments were performed on these samples in saturated water at the atmospheric pressure. Water could not be wicked by the original stainless steel surface, and surface wicking ability was gradually enhanced with increasing the etching time. After being etched by 3 minutes, the surface wicking flux reached 20 μL/(mm2·s). As compared to the original surface, the use of this wicking surface was exhibited to shorten the cool-down time by about 80%, and the critical heat flux was improved by about 84%. The construction of surface wicking can increase the solid-liquid contact areas and intensify the fluctuations of vapor film, suppress the emergence of stable film boiling, and lead to significant heat transfer enhancement during transition boiling.