| 引用本文: | 邵苛苛,宋孟杰,张旋,康文希,张颖,张龙,刘源鑫.冰中微尺度受陷气泡生长分布特性与宏观热力影响综述[J].哈尔滨工业大学学报,2024,56(6):152.DOI:10.11918/202311080 |
| SHAO Keke,SONG Mengjie,ZHANG Xuan,KANG Wenxi,ZHANG Ying,ZHANG Long,LIU Yuanxin.A review of micro-scale trapped air bubble growth distribution characteristics and thermal mechanical effects in ice[J].Journal of Harbin Institute of Technology,2024,56(6):152.DOI:10.11918/202311080 |
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| 冰中微尺度受陷气泡生长分布特性与宏观热力影响综述 |
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邵苛苛1,2,宋孟杰1,2,张旋1,康文希3,张颖3,张龙1,刘源鑫1,4
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(1.北京理工大学 机械与车辆学院,北京 100081;2.汉阳大学 机械工程学院,首尔 04763; 3.北京市东城区东直门中学,北京 100007;4.北京京能能源技术研究有限责任公司,北京 100022)
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| 摘要: |
| 结冰是传热传质流动耦合的非线性、变密度液固相变过程,在自然界与工业界广泛存在且多呈负面影响。溶解于液态水中的微量空气在结冰时因冰晶挤压而汇聚后成核,形成较大气泡后因界面黏附力而停留在冻结锋面处,最终形成冰中大小各异、分布不一的微尺度受陷气泡。形成于结冰过程的微尺度受陷气泡,不仅因改变冰的内部结构、密度分布、导热系数及冻结速率而影响后期动态结冰过程,亦会影响结冰过程和结束后冰体的整体导热系数、热阻分布、抗压强度、应力分布等宏观热学、力学物理特性。为精准预测及控制结冰过程,开发和优化各类防除冰技术,微尺度受陷气泡的生长分布特性与宏观热力影响研究在学术界和工业界均备受关注。首先,以冰中微尺度受陷气泡为研究对象,从微观与宏观尺度对其成核机制、生长过程、分布特性和静态稳定性等进行综述。结果显示:气泡形状与冻结速率直接相关,当冻结速率大于25 μm/s时,冰中出现长短轴比小于5的蛋状受陷气泡；当冻结速率在5~25 μm/s时,冰中出现长短轴比大于5的针状受陷气泡；当冰冻结速率小于3 μm/s时,冰中未能发现任何受陷气泡。其次,通过对既有文献中各类研究成果的梳理分析,对受陷气泡全生命周期的影响因素及其对结冰时、成冰后热力物性的不同影响机制进行了梳理与解释。冰中受陷气泡因降低冰的密度及改变内部冰晶结构而会显著降低冰的有效导热系数。在融冰实验中,气泡体积分数为57%的冰比不含气泡的透明冰开始融化时间滞后约50%,相同时间内的融冰高度低36.81%。随气泡体积分数增加,冰的水平和竖直抗压强度均逐渐减小,当气泡体积分数由4%增加到34%时,水平和竖直方向抗压强度分别降低为原来的8.38%和8.10%。最后,基于既有受陷气泡研究成果,对目前存在的研究空白及发展趋势进行了预测与阐述。本综述对理清受陷气泡复杂特性、丰富结冰过程传质理论有较大帮助,亦可为既有防除冰技术的优化设计提供参考与借鉴。 |
| 关键词: 受陷气泡 结冰成核 生长分布特性 热学特性 力学特性 |
| DOI：10.11918/202311080 |
| 分类号:TB69 |
| 文献标识码:A |
| 基金项目:国家自然科学基金(52076013);北京市自然科学基金(4,2) |
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| A review of micro-scale trapped air bubble growth distribution characteristics and thermal mechanical effects in ice |
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SHAO Keke1,2,SONG Mengjie1,2,ZHANG Xuan1,KANG Wenxi3,ZHANG Ying3,ZHANG Long1,LIU Yuanxin1,4
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(1.School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China; 2.School of Mechanical Engineering, Hanyang University, Seoul 04763, Republic of Korea; 3.Beijing Dongzhimen High School, Beijng 100007,China; 4.Beijing Jingneng Energy Technology Research Co., Ltd., Beijing 100022, China)
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| Abstract: |
| Icing is a nonlinear, variable density liquid-solid phase change process coupled with thermal and mass transfer and flow, which occurs widely in nature and industry, often with negative consequences. Trace amounts of air dissolved in water converge and nucleate into larger bubbles during icing due to the extrusion of ice crystals. These bubbles then remain at the freezing front due to adhesion, ultimately forming microscale trapped air bubbles of varying sizes and distributions in ice. The formation of micro-scale trapped air bubbles in the icing process not only affects the later dynamic icing process by changing the internal structure, density distribution, thermal conductivity and freezing rate of ice, but also affects the overall thermal conductivity, thermal resistance distribution, compressive strength, stress distribution and other macroscopic thermal and mechanical properties of the ice body after the icing process concludes. To accurately predict and control the icing process, as well as to develop and optimize various types of anti-icing technologies, the study of the growth and distribution characteristics of microscale trapped air bubbles and the macro-thermal effects has attracted much attention in both academia and industry. Firstly, this paper takes micro-scale trapped air bubbles in ice as the research object, and reviews their nucleation mechanism, growth process, distribution characteristics and static stability from the micro and macro scales. The results show that the bubble shape is directly related to the freezing rate, and when the freezing rate exceeds 25 μm/s, egg-shaped trapped air bubbles with a length-to-width ratio smaller than 5 appear in ice. When the freezing rate is between 5 and 25 μm/s, needle-shaped trapped air bubbles with a length-to-width ratio larger than 5 appear in ice. No bubbles can be found in ice when the ice freezing rate is below 3 μm/s. Secondly, by reviewing and analyzing existing literature, the influencing factors of the whole life cycle of trapped air bubbles and their different influencing mechanisms on the thermal and mechanical characteristics during icing and after ice formation are summarized and explained. Trapped air bubbles in ice significantly reduce the effective thermal conductivity of the ice by lowering its the density and changing the internal ice crystal structure. In ice melting experiments, ice with a bubble volume fraction of 57% exhibits a delay of approximately 50% in the starting time of melting compared to clear ice without bubbles. Additionally, the ice with bubbles has a 36.81% lower meting height within the same time frame. With the increase of bubble volume fraction, both the horizontal and vertical compressive strength of the ice decrease gradually. When the bubble volume fraction increases from 4% to 34%, the horizontal and vertical compressive strengths decrease to 8.38% and 8.10% of the original values, respectively. Finally, based on existing research on trapped air bubbles, the current research gaps and development trends are predicted and elaborated. This review is helpful for clarifying the complex characteristics of trapped air bubbles and enriching the mass transfer theory of icing process. It can also provide references and insights for the optimal design of existing anti-deicing technologies. |
| Key words: trapped air bubble icing nucleation growth distribution characteristics thermal characteristics mechanical characteristics |
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