摘要
多孔介质内水冻结过程的传热传质问题普遍存在于寒区工程、食品冷冻保鲜和建筑、路面冻融破坏等领域。本研究在介观尺度下对多孔介质内水结冰相界面的演化机理进行了实验与模拟研究。首先通过单向冻结实验,研究了孔隙半径500μm微孔道内水冻结过程中相界面及温度场演变规律。然后通过数值模拟,研究了边界温度、孔隙间距、孔隙结构对相界面演变规律和水冻结速率的影响。结果表明,相界面相对曲率随孔隙半径减小而减小,在孔道中,相对曲率先减小后增大,使相界面从凹形向凸形变化。孔道内温度随时间下降先快后慢,其速率与温度梯度有关。过冷引起0℃等温线与相界面之间过冷带的形成。孔隙间距越小,孔道内的温度梯度突跃越剧烈,阻碍传热。在本文研究的四种孔隙结构中,圆形直排冻结速率最大。
Heat and mass transfer problems in the freezing process of water in porous media generally exist in the fields of engineering in cold region,food freezing and preservation,construction,and pavement freeze-thaw damage.In this study,the evolution mechanism of water freezing phase interface in porous media is studied at the mesoscale by experiments and simulations.Firstly,the evolution of phase interface and temperature field during water freezing in microchannels with pore radius of 500μm was studied by unidirectional freezing experiment.Then,the effects of boundary temperature,pore space and pore structure on the evolution of phase interface and water freezing rate were studied through numerical simulation.The results show that the relative curvature of the phase interface decreases with the decrease of pore radius.In the channel,the relative curvature decreases firstly and then increases,making the phase change from concave to convex.The temperature in the channel decreases quickly and then slowly with time,and the rate is related to the temperature gradient.Supercooling causes the formation of supercooled zone between 0℃isotherm and phase interface.The smaller the pore space is,the stronger the sudden temperature gradient in the pore channel is,which hinders heat transfer.Among the four pore structures studied in this paper,the circular straight-row has the highest freezing rate.
作者
王文松
杨英英
陈周林
杨晴雨
李帅华
武卫东
WANG Wensong;YANG Yingying;CHEN Zhoulin;YANG Qingyu;LI Shuaihua;WU Weidong(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering,Shanghai 200093,China)
出处
《化工学报》
EI
CSCD
北大核心
2022年第12期5343-5354,F0004,共13页
CIESC Journal
基金
国家自然科学基金项目(52006146)。
关键词
介观尺度
多孔介质
冻结
毛细力
相界面
mesoscale
porous media
freezing
capillary force
phase interface
