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The Definition and Determination of the Critical Fouling Layer Thickness

WU Shuang-ying, SU Chang, LI You-rong

Abstract （997）

PDF （285KB）（466）

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．

2009, 22 (4): 58-62. DOI: 10.3696/j.issn.1006-396X.2009.04.015

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The Determination of Turbulent Convective Heat Transfer Coefficient Through a Duct Considering Fouling Mass Transfer Process

WU Shuang-ying, SU Chang, LI You-rong

Abstract （274）

PDF （2382KB）（213）

Based on the combination of thin film model reflecting heat and mass transfer synchronously with the asymptotic fouling model proposed by Kern and Seaton, the convective heat transfer characteristic through a duct under turbulent flow conditions at the forming period of fouling was investigated and a quantitative expression of the turbulent convective heat transfer coefficient through a duct considering fouling mass transfer process was presented. The results show that the deposition of fouling makes the whole convective heat transfer coefficient is decrease gradually with time and close to a constant. Compared with a clean duct, the heat transfer at the initial forming period of fouling is enhanced, but this phenomenon is not obvious. Furthermore, the whole convective heat transfer coefficient is determined by duct diameter, duct wall temperature, flow velocity, and inlet temperature of fluid, etc.

2008, 21 (1): 51-54.