摘要
实验研究了质量浓度为2％和5％的相变微胶囊悬浮液在等热流加热圆管内的对流换热特性，结果表明：相变微胶囊颗粒的加入明显增强了溶液的冷却效果，有效降低了管道壁面温度，并且悬浮液浓度越高，管道壁面温度越低；相变微胶囊悬浮液使管道入口段的局部努塞尔数明显增大，但随着流程进行，对流换热增强的幅度减弱；和水相比，浓度2％的相变微胶囊悬浮液的平均努塞尔数提高ll％，悬浮液具有较好的强化换热效果；但浓度5％的悬浮液的平均努塞尔数低于水，这是由于5％的悬浮液粘度增加明显，悬浮液的高粘度和低导热率减缓了圆管中心处微胶囊颗粒的吸热相变，降低了5％悬浮液的强化换热效果。
The convective heat transfer characteristics of microencapsulated phase change material （MEPCM） suspensions with mass concentrations of 2% and 5% flowing in a circular tube under the uni- form wall heat flux were experimentally investigated. The results show that the employment of MEPCM particles significantly increases the cooling performance of the fluid, and effectively decreases the wall temperature of the tube. In addition, the wall temperature decreases with the increase in the mass concen- tration of MEPCM suspensions. At the entrance region of the tube, the local Nusselt number of MEPCM suspensions is clearly higher than that of pure water, however, the heat transfer enhancement gradually weakens along the flow direction. Compared to the pure water, the mean Nusseh number of 2% suspen- sions is improved by 11%, and MEPCM suspensions have the efficient heat transfer enhancement, whereas the mean Nusseh number of 5 % suspensions is lower compared with the pure water, mostly due to the noticeable viscosity increase for the case with 5 % suspensions. The higher viscosity and lower ther- mal conductivity of suspensions slow down the phase change of MEPCM particles in the center of the tube, thus the heat transfer performance of 5% suspensions is deteriorated.
作者
田丽亭
李帅
崔志强
孔祥飞
TIAN Li-ting;LI Shuai;CUI Zhi-qiang;KONG Xiang-fei(School of Energy and Environmental Engineering,Hebei University of Technology,Tianjin,China,Post Code ：300401)
出处
《热能动力工程》
CAS
CSCD
北大核心
2018年第10期16-21,共6页
Journal of Engineering for Thermal Energy and Power
基金
国家自然科学基金(51576059)
河北省自然科学基金(E2014202032)~~
关键词
相变材料
微胶囊
悬浮液
对流换热
圆管
phase change material
microcapsule
suspension
convective heat transfer
circular tube
