Abstract: Based on the effect of fouling on heat transfer process，the critical fouling layer thickness was firstly put forward． The expressions of the critical fouling layer thickness were given and the effect of relative parameters on the critical fouling
layer thickness was discussed．In the meantime， the critical fouling layer thickness was compared with the critical thermal insulation layer thickness．The results show that the critical fouling layer thickness may be theoretically used to explain the phenomena of enhancement heat transfer at the initial forming period of fouling under fixed conditions． Furthermore， the critical fouling layer thickness is determined by mass flow rate of fluid， the physical properties of fluid and the thermal conductivity of fouling layer itself， etc． Meanwhile， the presence of the critical fouling layer thickness is subjected to the specific conditions of convective heat transfer，and the critical fouling layer thickness is different from the critical thermal insulation layer thickness although the fouling layer and thermal insulation layer both have poor thermal conductivity．

Key words: Convective heat transfer , Conduction , Critical fouling layer thickness , Critical thermal insulation layer thickness

摘要： 基于污垢影响传热过程的特性出发,提出临界污垢层厚度的概念并给出相关算式,讨论相关参数对临界污垢层厚度的影响,并和临界热绝缘层厚度进行比较。研究结果表明,临界污垢层厚度在一定条件下可用来解释结垢初期传热强化的现象;临界污垢层厚度的大小受到流体的质量流量、流体的物性以及污垢层本身的导热系数等参数的影响;临界污垢层厚度的存在受具体的对流换热条件限制;尽管污垢层和热绝缘层都是热的不良导体,但临界污垢层厚度不同于临界热绝缘层厚度。

关键词: 对流换热 , 导热 , 临界污垢层厚度 , 临界热绝缘层厚度