竖直超疏水翅片间霜层动态生长特性

doi:10.11949/0438-1157.20201491

摘要/Abstract

摘要：

搭建了竖直翅片间霜层生长可视化实验平台，分别制备了铝基亲水、超亲水和超疏水平板换热器，研究了翅片间距、表面润湿性能和环境温湿度等对竖直翅片间霜层生长动态特性的影响。实验结果表明，翅片间霜层的生长过程以临界间距（约1 mm）为界可分为线性快速增长阶段和缓慢增长阶段；相同工况下，亲水表面、超亲水表面和超疏水表面翅片间结霜持续时间分别为177、387和482 min。亲水表面霜层的增长速度分别为超亲水表面和超疏水表面的2倍和3倍。较低的表面温度和较高的环境湿度由于相变过饱和度的增加而提升了霜层增长速度；此外，翅片间霜层积聚过程中霜层密度随时间变化先增长，之后霜层密度增速放缓甚至不再增长直至结霜过程结束。

关键词: 换热器, 结霜, 热力学, 超疏水, 动态学, 界面

Abstract:

Frost build-up on the heat exchanger results in an increase in heat transfer resistance and pressure drop, leading to additional energy consumption and operational costs of heat pump systems. Superhydrophobic surface has been shown to retard frosting significantly due to its efficient removal of condensed droplets prior to freezing via coalescence induced droplet jumping. Recently, heat exchangers and fin pitch are designed elaborately to balance heat transfer and pressure drop. Exploring the effect of fin pitch and surfaces wettabilities on frosting rates on surfaces is crucial when designing high efficient heat exchangers. In this paper, frosting dynamics between two parallel heat exchangers with different wettabilities were studied experimentally. Frost growth was continually recorded through high-resolution optical camera from the side and top of the gap between the parallel fins. Average frost thickness was calculated visually by high resolution images and MATLAB image processing techniques. Test experiments were conducted for hydrophilic, superhydrophilic and superhydrophobic surfaces under different frosting conditions with fin pitch of 2, 4, 6, and 8 mm. Results indicated that frost process could be divided into two different regimes, called rapidly frosting and slowly frosting regime. Frost growth rates were distinctly higher under higher relative humidity and lower surface temperature. In addition, frost growth rates on superhydrophobic surface was lower than the hydrophilic and superhydrophilic surfaces significantly. This work here not only help to optimize the design of high efficient coated heat exchangers of heat pump systems, but also provide insights into understanding the complex thermodynamics theory of governing the condensation frosting process on surfaces.

Key words: heat exchanger, frost, thermodynamics, superhydrophobic, dynamics, interface

中图分类号:

TK 519

苏伟, 芦志飞, 张小松. 竖直超疏水翅片间霜层动态生长特性[J]. 化工学报, 2021, 72(S1): 244-256.

SU Wei, LU Zhifei, ZHANG Xiaosong. Frost growth dynamics on vertical superhydrophobic fins[J]. CIESC Journal, 2021, 72(S1): 244-256.

图/表 14

图1 竖直换热器翅片间结霜实验装置

Fig.1 Image of experimental setup of frost growth on vertical heat exchanger

图2 换热器表面的扫描电镜图

Fig.2 SEM image of heat exchanger surfaces

图3 结霜可视化实验系统

Fig.3 Schematic diagram of experimental visual system

图4 换热器表面温度的变化

Fig.4 Temperature variation of cold plate heat exchanger

图5 基于MATLAB图像处理技术进行霜层厚度测量

Fig.5 Measurement of frost thickness by MATLAB software

图6 结霜质量测量方法

Fig.6 Measurement of frost mass

图7 霜层生长的物理模型

Fig.7 Physical model of frost growth

图8 表面润湿性能及翅片间距对结霜速度的影响

Fig.8 Effect of fin pitch and surface wettability on frost growth

图9 表面润湿性能对表面冷凝液滴覆盖率的影响

Fig.9 Effect of surface wettability on condensation droplet coverage

图10 不同润湿性能表面霜层增长过程

Fig.10 Effect of surface wettability on frost growth

图11 不同换热器间距的结霜增长速度与均一化速度对比

Fig.11 Comparison of frost thickness and normalized frost thickness for varied fin pitch

图12 换热器表面温度对结霜速度的影响

Fig.12 Effect of fin pitch and surface wettability on frost growth

图13 环境湿度对结霜速度的影响

Fig.13 Effect of air relative humidity on frost growth for varied fin pitch and surface temperature

图14 结霜过程霜层密度变化

Fig.14 Measured frost density for hydrophilic surface at varied surface temperature for fin pitch

参考文献 31

1	Xu W, Liu C P, Li A G, et al. Feasibility and performance study on hybrid air source heat pump system for ultra-low energy building in severe cold region of China [J]. Renewable Energy, 2020, 146: 2124-2133.
2	Zhang Q L, Zhang L, Nie J Z, et al. Techno-economic analysis of air source heat pump applied for space heating in Northern China [J]. Applied Energy, 2017, 207: 533-542.
3	张小松, 文先太, 梁彩华. 适合夏热冬冷地区的新型双高效热泵系统[J]. 制冷与空调, 2013, 13(11): 6-10, 15.
	Zhang X S, Wen X T, Liang C H. New type of dual high-efficiency heat pump system suited to hot summer and cold winter zones [J]. Refrigeration and Air-Conditioning, 2013, 13(11): 6-10, 15.
4	乐慧, 李好玥, 江亿. 用空气源热泵实现农村采暖的“煤改电”同时为电力削峰填谷[J]. 中国能源, 2016, 38(11): 9-15.
	Yue H, Li H Y, Jiang Y. Realization of substituting coal with electricity and enhancing the efficiency of electricity allocation by using air source heat pump [J]. Energy of China, 2016, 38(11): 9-15.
5	张春林, 程港, 钱志博. 双级压缩空气源热泵在农村煤改电项目中的应用[J]. 建筑热能通风空调, 2018, 37(8): 54-56, 53.
	Zhang C L, Cheng G, Qian Z B. Application of two-stage compressed air source heat pump in rural coal to electricity project [J]. Building Energy & Environment, 2018, 37(8): 54-56, 53.
6	余丽霞, 付祥钊, 肖益民. 空气源热泵在长江流域的气候适宜性研究[J]. 暖通空调, 2011, 41(6): 96-99.
	Yu L X, Fu X Z, Xiao Y M. Climate suitability of air-source heat pumps in Yangtze valley [J]. Heating Ventilating & Air Conditioning, 2011, 41(6): 96-99.
7	邱君君, 张小松, 李玮豪. 无霜空气源热泵系统冬季除湿性能初步实验[J]. 化工学报, 2019, 70(4): 1605-1613.
	Qiu J J, Zhang X S, Li W H. Experimental research on a novel frost-free air source heat pump system [J]. CIESC Journal, 2019, 70(4): 1605-1613.
8	Zhu J H, Sun Y Y, Wang W, et al. Developing a new frosting map to guide defrosting control for air-source heat pump units [J]. Applied Thermal Engineering, 2015, 90: 782-791.
9	Wang F, Liang C H, Zhang X S. Research of anti-frosting technology in refrigeration and air conditioning fields: a review [J]. Renewable and Sustainable Energy Reviews, 2018, 81: 707-722.
10	Léoni A, Mondot M, Durier F, et al. State-of-the-art review of frost deposition on flat surfaces [J]. International Journal of Refrigeration, 2016, 68: 198-217.
11	Song M J, Deng S M, Dang C B, et al. Review on improvement for air source heat pump units during frosting and defrosting [J]. Applied Energy, 2018, 211: 1150-1170.
12	Amer M, Wang C C. Review of defrosting methods [J]. Renewable and Sustainable Energy Reviews, 2017, 73: 53-74.
13	Dong J K, Jiang Y Q, Deng S M, et al. Improving reverse cycle defrosting performance of air source heat pumps using thermal storage-based refrigerant sub-cooling energy [J]. Building Services Engineering Research and Technology, 2012, 33(2): 223-236.
14	Su W, Zhang X S. Performance analysis of a novel frost-free air-source heat pump with integrated membrane-based liquid desiccant dehumidification and humidification [J]. Energy and Buildings, 2017, 145: 293-303.
15	李玮豪, 邱君君, 张小松. 无霜空气源热泵系统冬季运行性能实验[J]. 化工学报, 2018, 69(12): 5220-5228.
	Li W H, Qiu J J, Zhang X S. Experimental research on new type of frost-free air source heat pump system in winter [J]. CIESC Journal, 2018, 69(12): 5220-5228.
16	吴晓敏, 褚福强, 陈永根. 疏水表面结霜初期液滴生长的理论分析[J]. 化工学报, 2015, 66(S1): 60-64.
	Wu X M, Chu F Q, Chen Y G. Theoretical analysis of droplets growth in early stage of frosting on hydrophobic surfaces [J]. CIESC Journal, 2015, 66(S1): 60-64.
17	Chu F Q, Wen D S, Wu X M. Frost self-removal mechanism during defrosting on vertical superhydrophobic surfaces: peeling off or jumping off [J]. Langmuir, 2018, 34(48): 14562-14569.
18	Lü J, Song Y L, Jiang L, et al. Bio-inspired strategies for anti-icing [J]. ACS Nano, 2014, 8(4): 3152-3169.
19	汪峰, 梁彩华, 张友法, 等. 结霜初期超疏水表面凝结液滴的自跳跃脱落及其对结霜过程的影响[J]. 东南大学学报(自然科学版), 2016, 46(4): 757-762.
	Wang F, Liang C H, Zhang Y F, et al. Jumping of condensation droplets on superhydrophobic surfaces at early frosting stage and its effects on frost formation [J]. Journal of Southeast University (Natural Science Edition), 2016, 46(4): 757-762.
20	Jeevahan J, Chandrasekaran M, Britto Joseph G, et al. Superhydrophobic surfaces: a review on fundamentals, applications, and challenges [J]. Journal of Coatings Technology and Research, 2018, 15(2): 231-250.
21	马强, 吴晓敏. 表面特性对结霜和融霜排液的影响[J]. 化工学报, 2017, 68(S1): 90-95.
	Ma Q, Wu X M. Effect of surface wettability on frosting, defrosting and drainage [J]. CIESC Journal, 2017, 68(S1): 90-95.
22	褚福强, 吴晓敏, 朱毅. 超疏水表面上多液滴合并触发液滴弹跳现象的理论分析[J]. 工程热物理学报, 2017, 38(2): 352-357.
	Chu F Q, Wu X M, Zhu Y. Theoretical model for multidroplet coalescence induced droplet jumping on superhydrophobic surfaces [J]. Journal of Engineering Thermophysics, 2017, 38(2): 352-357.
23	Kreder M J, Alvarenga J, Kim P, et al. Design of anti-icing surfaces: smooth, textured or slippery? [J]. Nature Reviews Materials, 2016, 1: 15003.
24	Boreyko J B, Collier C P. Delayed frost growth on jumping-drop superhydrophobic surfaces [J]. ACS Nano, 2013, 7(2): 1618-1627.
25	张鲁梦, 郭宪民, 薛杰. 翅片管换热器表面霜层生长特性的实验研究[J]. 化工学报, 2018, 69(S2): 186-192.
	Zhang L M, Guo X M, Xue J. Experimental study of frost growth characteristics on surface of finned-tube heat exchangers [J]. CIESC Journal, 2018, 69(S2): 186-192.
26	梁彩华, 汪峰, 吕艳, 等. 翅片表面特性对结霜过程影响的实验研究[J]. 东南大学学报(自然科学版), 2014, 44(4): 745-750.
	Liang C H, Wang F, Lü Y, et al. Experimental study on effect of surface characteristic of fin on frost formation [J]. Journal of Southeast University (Natural Science Edition), 2014, 44(4): 745-750.
27	汪峰. 超疏水翅片表面结霜/融霜作用机理与特性研究[D]. 南京: 东南大学, 2017.
	Wang F. Study on mechanism and characteristics of frosting and defrosting on superhydrophobic fin surface [D]. Nanjing: Southeast University, 2017.
28	Adamson A W, Gast A P. Physical Chemistry of Surfaces [M]. New York: Interscience, 1967.
29	黄玲艳. 表面特性对冷壁面结霜过程影响的研究[D]. 北京: 北京工业大学, 2011.
	Huang L Y. Astudy on the effects of cold surface characteristics on frost formation [D]. Beijing: BeijingUniversity of Technology, 2011.
30	El Cheikh A, Jacobi A. A mathematical model for frost growth and densification on flat surfaces [J]. International Journal of Heat and Mass Transfer, 2014, 77: 604-611.
31	da Silva D L, Hermes C J L, Melo C. Experimental study of frost accumulation on fan-supplied tube-fin evaporators [J]. Applied Thermal Engineering, 2011, 31(6/7): 1013-1020.

[1]	苏伟, 马东旭, 金旭, 刘忠彦, 张小松. 表面润湿性对霜层传递特性影响可视化实验研究[J]. 化工学报, 2023, 74(S1): 122-131.
[2]	周晓庆, 李春煜, 杨光, 蔡爱峰, 吴静怡. 液滴撞击不同曲率过冷波纹面结冰动力学行为及机理研究[J]. 化工学报, 2023, 74(S1): 141-153.
[3]	毕丽森, 刘斌, 胡恒祥, 曾涛, 李卓睿, 宋健飞, 吴翰铭. 粗糙界面上纳米液滴蒸发模式的分子动力学研究[J]. 化工学报, 2023, 74(S1): 172-178.
[4]	张龙, 宋孟杰, 邵苛苛, 张旋, 沈俊, 高润淼, 甄泽康, 江正勇. 管翅式换热器迎风侧翅片末端霜层生长模拟研究[J]. 化工学报, 2023, 74(S1): 179-182.
[5]	张义飞, 刘舫辰, 张双星, 杜文静. 超临界二氧化碳用印刷电路板式换热器性能分析[J]. 化工学报, 2023, 74(S1): 183-190.
[6]	邹启宏, 李乾, 葛天舒. 基于多目标下的两级并联除湿热泵系统实验研究[J]. 化工学报, 2023, 74(S1): 265-271.
[7]	杨欣, 王文, 徐凯, 马凡华. 高压氢气加注过程中温度特征仿真分析[J]. 化工学报, 2023, 74(S1): 280-286.
[8]	常明慧, 王林, 苑佳佳, 曹艺飞. 盐溶液蓄能型热泵循环特性研究[J]. 化工学报, 2023, 74(S1): 329-337.
[9]	张化福, 童莉葛, 张振涛, 杨俊玲, 王立, 张俊浩. 机械蒸汽压缩蒸发技术研究现状与发展趋势[J]. 化工学报, 2023, 74(S1): 8-24.
[10]	胡建波, 刘洪超, 胡齐, 黄美英, 宋先雨, 赵双良. 有机笼跨细胞膜易位行为的分子动力学模拟研究[J]. 化工学报, 2023, 74(9): 3756-3765.
[11]	陆俊凤, 孙怀宇, 王艳磊, 何宏艳. 离子液体界面极化及其调控氢键性质的分子机理[J]. 化工学报, 2023, 74(9): 3665-3680.
[12]	张曼铮, 肖猛, 闫沛伟, 苗政, 徐进良, 纪献兵. 危废焚烧处理耦合有机朗肯循环系统工质筛选与热力学优化[J]. 化工学报, 2023, 74(8): 3502-3512.
[13]	林典, 江国梅, 徐秀彬, 赵波, 刘冬梅, 吴旭. 硅基类液防原油黏附涂层的研制及其减阻性能研究[J]. 化工学报, 2023, 74(8): 3438-3445.
[14]	傅予, 刘兴翀, 王瀚雨, 李海敏, 倪亚飞, 邹文静, 雷月, 彭永姗. F₃EACl修饰层对钙钛矿太阳能电池性能提升的研究[J]. 化工学报, 2023, 74(8): 3554-3563.
[15]	张贲, 王松柏, 魏子亚, 郝婷婷, 马学虎, 温荣福. 超亲水多孔金属结构驱动的毛细液膜冷凝及传热强化[J]. 化工学报, 2023, 74(7): 2824-2835.