Influence of the adhesion force crystal/heat exchanger surface on fouling mitigation

The accumulation of unwanted crystalline deposits (fouling) reduces the eff iciency of heat exchangers considerably. In order to decrease the cost of f ouling two strategies have been developed. The first fouling mitigation str ategy is based on the modification of energy and geometry related character istics of the heat transfer surface to realize an increased duration of the induction period. By means of a DSA (drop shape analysis) measurement devi ce the interaction at the interface crystal/heat transfer surface is determ ined. The deployment of the fracture energy model and the interfacial defec t model relates wetting characteristics to the adhesion phenomenon. Hence, a first estimation of the optimal choice of surface material is realized. F urthermore, the influence of surface topography on interfacial interactions has been analyzed. The second fouling mitigation strategy is based on the adjustment of the hydrodynamic flow conditions using a pulsation technique. Here, single strokes of higher velocity are superimposed on the stationary flow. These strokes shift the equilibrium of forces to an improved removal process. Fouling experiments have proved that pulsation is a powerful tool to mitigate the built-up of fouling layers on heat transfer surfaces. (C) 1999 Elsevier Science S.A. All rights reserved.