Mass transfer at erosion‐corrosion roughened surfaces

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 mm, and pitch/height in the range 5 to 10, resulted in mass transfer enhancement up to 100%, in both the slurry and the solution, with the maximum effect occurring at the dimensionless roughness height e + ≈︁ 30.