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微小通道内不同润湿性表面流动冷凝传热

袁金斗1 王彦博1 胡涵1 余雄江1 徐进良1

(1.华北电力大学低品位能源多相流与传热北京市重点实验室, 北京 102206)

【摘要】利用丝网烧结和聚四氟乙烯溶液 (Teflon) 浸渍法, 在铜表面上制备了亲疏水匹配的结构, 即在疏水四氟涂层上有阵列排布的椭圆亲水点, 仅有四氟涂层的全疏水表面和不作修饰的全亲水铜表面作为对照, 考察了以这三种表面为底部换热区域的矩形微小通道 (水力直径1.5 mm) 的换热特性和流动特性。实验的通道内蒸汽质量流速为10~60 kg·m-2·s-1, 干度为0.3~1, 亲疏水匹配表面与亲水表面相比, 蒸汽冷凝传热系数 (HTC) 最高增加了454.6%, 与全疏水表面相比, 传热系数最高增加了107.3%, 利用高速相机拍摄可视化照片, 观察了通道内气液两相, 尤其是表面液滴成核、聚并、冲刷的周期运动过程, 解释了亲疏水匹配表面强化传热的机理。

【关键词】 凝结;亲疏水表面;微小通道;传热系数;

【DOI】

【基金资助】 国家自然科学基金重点项目 (51436004) ; 国家自然科学基金项目 (51676071) ;

Flow condensation heat transfer on surfaces with different wettability in mini-channel

YUAN Jindou1 WANG Yanbo1 HU Han1 YU Xiongjiang1 XU Jinliang1

(1.Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy, North China Electric Power University, Beijing, China 102206)

【Abstract】The hydrophobic surface embedded with arrayed hydrophilic dots was prepared on a copper surface with mesh screen and Teflon solution. Completely hydrophilic copper surface, completely hydrophobic Teflon-coated surface and hydrophilic/hydrophobic hybrid surface are taken into consideration which serve as the bottom heat transfer area of rectangular mini-channels (1.5 mm hydraulic diameter). In this experiment, the vapor mass velocity ranges from 10 kg·m−2·s−1 to 60 kg·m−2·s−1, while the vapor quality from 0.3 to 1. According to the experimental investigation, the steam condensation heat transfer coefficient on hybrid surface is about 454.6% higher than that of the completely hydrophilic surface and 107.3% higher than the completely hydrophobic surface at most. A high-speed camera provides the photos of two-phase flow pattern, especially the periodic behavior of the droplets nucleation, coalescence and flush which can explain the mechanism of heat transfer enhancement.

【Keywords】 condensation; hydrophilic/hydrophobic surface; mini-channel; heat transfer coefficient;

【DOI】

【Funds】 Key Program of the National Natural Science Foundation of China (51436004); National Natural Science Foundation of China (51676071) ;

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This Article

ISSN:0438-1157

CN: 11-1946/TQ

Vol 69, No. 10, Pages 4156-4166+4496

October 2018

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Article Outline

Abstract

  • Introduction
  • 1 Surface preparation and characterization
  • 2 Mini-channel packaging and experimental system
  • 3 Experimental results and discussion
  • 4 Mechanism of enhanced heat transfer in hydrophobic–hydrophilic hybrid channel
  • 5 Conclusion
  • Symbol description
  • References