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Rates of pipewall oxygen mass transfer in a 39 mm ID vertical pipe carrying an aqueous slurry containing 20 vol% 30-50 mesh sand have been determined electrochemically with twin in-line flow cells, one containing a mild steel specimen previously roughened by erosion-corrosion and the other a smooth specimen. Measurements were also made without the solids present.The three-dimensional rough surface, with roughness height approximately 0.2 rnm, and pitch/height in the range 5 to 10, resulted in mass transfer enhancement up to loo%, in both the slurry and the solution, with the maximum effect occurring at the dimensionless roughness height e + = 30.Les taux de transfert de matitre d'oxyghne h la paroi dans un tube vertical de 39 mm dc diambtre inttrieur dans lequel s'tcoule une suspension aqueuse contenant 20% en volume de particules de 30 h 50 mesh, ont ttt d6terminCes par une m6thode tlectrochimique qui utilise des cellules 1 tcoulement en ligne jumeltes; I'une de ces cellules contient un Cchantillon d'acier doux prhlablement dkgrossi par un processus combint d'trosion et de corrosion, l'autre un tchantillon lisse. Ce systeme a tgalement Ctt utilist pour effecteur des mesures en I'absence de particules solides.La surface rugueuse tridimensionnelle, dont la hauteur des asptritts est d'environ 0,2 mm, et le rapport padhauteur de I'ordre de 5 h 10, a permis une augmentation du transfert de matiere allant jusqu'h loo%, et pour la suspension et pour la solution; I'effet maximum est apparu h une rugositt adimensionnelle e + de l'ordre de 30.

Electrochemical measurements of mass transfer in a turbulent pipe flow are presented. In particular the effect of flow obstacles, such as orifices and circumferential slots with varying diameter and axial length, has been studied. The results also include measurements of mass transfer downstream, a sudden expansion or reduction of the tube diameter. The experiments were performed at a Schmidt number of 1460 and Reynolds numbers ranging between 1·104 and 3·105 . The work presented in this paper is a part of a project aiming to study the relation between corrosion and mass transfer at high flow rates with particular emphasis on disturbed turbulent pipe flow.

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