The condensation of steam containing low concentrations of trimethylamine

The morphology of the films formed during the condensation of steam, containing a low mass fraction of trimethylamine, are very different from those described in the earlier parts of this test series and the dynamic nature of this film morphology does not appear to have been previously reported. The video analysis of these films suggests that at low concentrations they form a very thin continuous film, which moves with a rapid circumferential velocity. At higher concentrations this film supports condensate drops that are rapidly formed at the top of the tube. These drops do not grow or move relative to each when they are conveyed down the tube and take time to be incorporated into the base layer at the bottom of the tube. It is not clear what influence these drops have on the rates of condensation. The size distribution of the drops tends to become more uniform at higher trimethylamine concentrations. Measurements of the drop velocities suggest that they and the base layer moves with a velocity of 0.1 m/s. The maximum heat transfer rate through these films is four times greater than that predicted by the Nusselt equation and it occurs with a trimethylamine mass fraction of 0.0003.