Impact of the surface roughness of AISI 316L stainless steel on biofilm adhesion in a seawater-cooled tubular heat exchanger-condenser

The present study evaluated biofilm growth in AISI 316L stainless steel tubes for seawater-cooled exchanger-condensers that had four different arithmetic mean surface roughness values ranging from 0.14 mu m to 1.2 mu m. The results of fluid frictional resistance and heat transfer resistance regarding biofilm formation in the roughest surface showed increases of 28.2% and 19.1% respectively, compared with the smoothest surface. The biofilm thickness taken at the end of the experiment showed variations of up to 74% between the smoothest and roughest surfaces. The thermal efficiency of the heat transfer process in the tube with the roughest surface was 17.4% greater than that in the tube with the smoothest surface. The results suggest that the finish of the inner surfaces of the tubes in heat exchanger-condensers is critical for improving energy efficiency and avoiding biofilm adhesion. This may be utilised to reduce biofilm adhesion and growth in the design of heat exchanger-condensers.