Theoretical and experimental studies of heat transfer with moving phase-change interface in freezing and thawing of porous potting soil  

作　　者：Michael K.H.LEUNG Kit-ying CHAN 

机构地区：[1]Department of Mechanical Engineering,the University of Hong Kong

出　　处：《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》2009年第1期1-6,共6页浙江大学学报（英文版）A辑（应用物理与工程）

基　　金：Project(No.10206014)supported by Research Grant Council Direct Allocation Fund from the University of Hong Kong,China

摘　　要：Soil in a cold region is subject to frequent freezing and thawing cycles.Soil frozen for a prolonged period may cause adverse freeze damage to the plants due to cell dehydration or root cell rupture.It is important to understand the detailed heat transfer behaviors of the freezing and thawing processes to prevent freeze damage,and to devise proper mitigation measures for effective pot planting in cold regions.A theoretical model was developed to analyze the transient moving phase-change interface heat transfer in the freezing and thawing of porous potting soil.The theoretical derivation is based on the assumption that the soil freezes completely at a single temperature.Microscopic poromechanic effects on heat transfer behavior were ignored.The spatial domain of the problem was simplified to a 1D spherical coordinate system with variation in the radial direction.Green's function was applied to solve for the time-dependent body temperature.Experiments were conducted for validation of the theoretical model.Reasonable agreement between the theoretical predictions and experimental measurements was obtained.The theoretical model developed can be easily used to determine the sensitivity of various parameters in the freezing/thawing processes,e.g.,thermal properties of soil,ambient temperature,and planting pot size.Soil in a cold region is subject to frequent freezing and thawing cycles. Soil frozen for a prolonged period may cause adverse freeze damage to the plants due to cell dehydration or root cell rupture. It is important to understand the detailed heat transfer behaviors of the freezing and thawing processes to prevent freeze damage, and to devise proper mitigation measures for effective pot planting in cold regions. A theoretical model was developed to analyze the transient moving phase-change interface heat transfer in the freezing and thawing of porous potting soil. The theoretical derivation is based on the assumption that the soil freezes completely at a single temperature. Microscopic poromechanic effects on heat transfer behavior were ignored. The spatial domain of the problem was simplified to a 1 D spherical coordinate system with variation in the radial direction. Green＇s function was applied to solve for the time-dependent body temperature. Experiments were conducted for validation of the theoretical model Reasonable agreement between the theoretical predictions and experimental measurements was obtained. The theoretical model developed can be easily used to determine the sensitivity of various parameters in the freezing/thawing processes, e.g., thermal properties of soil, ambient temperature, and planting pot size.

关 键 词：Porous soil Freezing Thawing Moving phase-change interface Theoretical model 

分 类 号：S152[农业科学—土壤学]