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Proceedings of an International Conference on Mitigation of Heat Exchanger Fouling and Its Economic and Environmental Implications

ISSN:
1-56700-172-6 (Print)

MODIFICATION OF THE CHARACTERISTICS OF HEAT TRANSFER SURFACES AS A FOULING MITIGATION STRATEGY

M. Forster
Institute of Heat and Mass Transfer, RWTH Aachen University, Eilfschornsteinstraβe 18, D-52062 Aachen, Germany; Institut fur Verfahrens- und Kerntechnik Technische Universitat Braunschweig Langer Kamp 7, D-38106 Braunschweig, Germany

M. Bohnet
Institut fur Verfahrens- und Kerntechnik Technische Universitat Braunschweig Langer Kamp 7, D-38106 Braunschweig, Germany

Abstract

The accumulation of unwanted crystalline deposits (fouling) reduces the efficiency of heat exchangers [1]. In order to adjust the operating conditions with respect to fouling mitigation a model for the description of the entire fouling process has to be established. The main disadvantage of known models is the lack of a description of the induction period. Similar to the fouling period the induction period is controlled by deposition and removal mechanisms. Both mechanisms are influenced by the energy and geometry related surface characteristics of the heat exchanger. The influence of surface energy properties can be described by the interfacial energy crystal/heat transfer surface. Hence, the investigation of the influence of interfacial interaction on nucleation and adhesion is subject to fouling research work. Based on the experimental determination of the surface energy of several metallic and polymeric materials their fouling performance when exposed to a liquid flow of a calcium sulphate solution has been examined. The interfacial defect model has been identified to be capable to relate wetting characteristics to the adhesive strength crystal/heat exchanger surface. In order to characterize the impact of surface topography on both adhesion and wetting modern surface texture parameters have been analyzed.