Investigations on crystallization fouling on PEEK films used as heat transfer surfaces: experimental results

Kinetics and quantity of crystallization fouling of calcium carbonate on polyether ether ketone (PEEK) surfaces are studied and compared with those on stainless steel. A laboratory scale set-up of a flat plate polymer film heat exchanger was used as a screening apparatus for the fouling experiments. The scaling affinity of the polymeric surfaces was found to be low compared to the stainless steel surface under equivalent conditions. Additionally, the polymer surface appears to be easier to clean due to a low adhesiveness. The low adhesiveness of crystals on polymers is attributed to their different surface properties (surface free energy and roughness) compared to stainless steel. The quantity of the deposit is also affected by the degree of supersaturation arising from higher local temperatures and overall concentrations. The deposits on the polymeric films were analyzed with respect to their appearance, distribution and thickness. Scanning electron microscopy (SEM) and optical coherence tomography (OCT) are used to determine the morphology of the deposited material and the fouling layer thickness, respectively.