| 摘要: |
| 本文研究了环境温度恒定为25 ℃、相对湿度为49%、体积为0.01 mL的液滴在﹣20 ℃裸铜底板的冻结实验，发现在附加交流磁场强度分别为2.0×10-3、2.5×10-3、3.0×10-3、3.5×10-3、4.0×10-3、4.5×10-3、5.0×10-3、5.5×10-3、6.0×10-3 T的作用下，液滴结晶过冷度增大，最大过冷度提高了2.08 ℃；但附加磁场会减小成核驱动力；相比无磁场情况下，液滴冷凝时间减少，凝结粒径相比无磁场下较小。通过对在相同温湿度下自然对流条件的冷铜底板结霜可视化研究发现，由于附加磁场使极性水分子有序的在底板排列，较无磁场下液滴结晶过程熵增更小，在宏观上呈现液滴有序排列。此外，实验发现在0～6×10-5 T的磁场强度范围，随着磁场强度的增大，平板单位面积结霜量减小，单位面积结霜量与交流磁场强度有较高的相关性，得到了拟合关系式。 |
| 关键词: 交流磁场 液滴冻结 过冷度 单位面积结霜量 |
| DOI： |
| 投稿时间：2019-02-08 修订日期：2019-07-23
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| 基金项目:天津市高等学校科技发展基金计划项目( 170018)，天津商业大学新进人员科研启动项目( R160117) 和武清区科技发展项目（WQKJ2001633）资助。 |
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| Study on the Frosting Characteristics of Bare Copper Surface UnderWeak Alternating Magnetic Field |
|
Meng Yu, Liu Bin, Shan LiangLiang, Zhang Rui, Chen Aiqiang, Georges EL ACHKAR, Bennacer Rachid
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| (Tianjin Key Lab of Refrigeration Technology, Tianjin University of Commerce) |
| Abstract: |
| In this paper, the frosting at a bare copper cold plate in a natural convective environment were studied. The temperature and relative humidity of the inflowing air were 25 °C and 49%, respectively, and the copper plate was maintained at -20 °C.An AC magnetic field with the strengths of 2.0×10-3, 2.5×10-3, 3.0×10-3, 3.5×10-3, 4.0×10-3, 4.5×10-3, 5.0×10-3, 5.5×10-3, and 6.0×10-3 T were applied to the frosting process. The results showed that thesupercooling degree of the crystals increased, but the driving force fornucleation decreased when magnetic field existed. Compared with the absence of a magnetic field, the droplet condensation time and the droplet size were reduced. Visualization studies demonstrated that the polar water molecules were arranged in the bottom plate in an orderly manner, the system’s entropy was reduced, and the driving force for crystallization was increaseddue to the additional magnetic field. The time to form a dense frost layer was reduced by 6%. In addition, with increased magnetic field strength, the amount of frost per unit area of the plate decreased under a weak AC magnetic field. A high correlation of the amount of frost deposited with the AC magnetic field strength was apparent and the fitted relationship was given in the paper. |
| Key words: AC magnetic field droplet degree of supercooling frosting intensity |
