摘要
实验研究了不同粒径金属粉末烧结制备的多孔涂层表面对垂直管外水蒸气冷凝传热的强化作用。发现:粒径为50μm的细粉覆盖一层及两层的多孔管的传热效果反而不如光管,使冷凝传热效果恶化;而粉末粒径为250μm的烧结表面的强化传热特性比光管提高10％～15％,而且也明显优于粒径为50μm的表面。同时,两种不同粒径表面,两层粉末错落堆积烧结表面的传热效果也优于单层粉末烧结表面。基于孔隙微观结构变化对冷凝液流动与导热的影响分析讨论了多孔烧结表面强化膜状冷凝传热的机理。
The condensation heat transfer of steam at atmospheric pressure was experimentally investigated by using a porous coating, which was sintered with metallic powders on the external surface of vertically orientated tubes. Four coatings were prepared with different particle diameters and coating thickness. The experimental results indicated that the condensation heat transfer characteristics of the porous coatings with particle diameter of 250μm was increased by 10%-15% compared that of bare tube, and much higher than that of the coatings with particle diameter of 50μm. However, the porous coating with the particle diameter of 50μm demonstrated lower heat transfer coefficient than that of bare tube. It was also found that the heat transfer performance increased with sintered porous layer number (or the porous coating thickness) increasing. Finally, the mechanism of condensation heat transfer enhancement was discussed with respect to the effect of microstructure among pores on the flow and heat conduction of the condensate.
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2003年第5期840-842,共3页
Journal of Engineering Thermophysics
基金
国家自然科学基金(No.59906002)
教育部留学回国人员科研启动基金(教外司留[1999]747号)
关键词
强化冷凝传热
烧结多孔涂层
孔隙微观结构
condensation heat transfer enhancement
sintered porous coating
microstructure among pores
