首页 | 本学科首页   官方微博 | 高级检索  
     


Ice crystal formation in the carbon nanotube suspension: A modelling approach
Authors:Kyuya Nakagawa  Napawon Thongprachan  Tawatchai Charinpanitkul  Wiwut Tanthapanichakoon
Affiliation:1. Department of Mechanical and System Engineering, University of Hyogo, 2167 Shosha, Himeji City, Hyogo 671-2280, Japan;2. Center of Excellence in Particle Technology, Faculty of Engineering, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok 10330, Thailand
Abstract:Freeze-dried porous solid foams were prepared from carbon nanotube (CNT) suspensions via either contact freezing with a heat exchanger or immersion freezing into a cryo-bath. Microstructures in the freeze-dried foam cast by ice crystals formed during the freezing step. It was found that domains of the carbon nanotubes in the freeze-dried solid foams were fairly well interconnected, and the microstructures were largely influenced by the freezing condition and freezing method. A mathematical model was proposed to simulate the observed thermal history during the freezing step; then theoretical predictions of the microstructural features were attempted. The simulated thermal history was in good agreement with experimental result. The resulting mean ice crystal sizes L* could be estimated from the calculated freezing front velocity (R) and the temperature gradient in the frozen zone (G). Interestingly, it was found that a correlation based on the power law (L*∝R?0.2G?0.2) was applicable to the present system for both the contact and immersion freezing methods. Though the fundamental ice crystallization phenomena were essentially the same for both freezing methods, actual temperature distribution and movement of the freezing front through the whole freezing bulk could control the morphology of ice crystal in the frozen matrix. In other words, good control of thermal flow in the freezing system would greatly contribute to rational design of microstructures of the CNT foam.
Keywords:
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号