Impact of surface treatment on the fouling of modified heat transfer surfaces

Heat exchangers are the workhorse of most chemical, petrochemical, food processing and power generating processes. However, the formation of materials with low thermal conductivity on heat exchanger surfaces can substantially reduce the efficiency of these devices. Of several fouling mitigation techniques, the alteration of surface properties and geometry is gaining increased attention due to its environmentally-friendly features. This study firstly intends to highlight the problem of fouling on heat transfer surfaces and the impact of surface properties on the fouling mechanisms of modified surfaces. Secondly, it also reports on a set of fouling runs that have been done on various heat transfer surfaces at ITW, The University of Stuttgart. With respect to the alteration of surface properties in terms of surface energy, it is shown the surfaces with lower surface energy are prone to lesser deposit built-up on the surface. On the other hand, the modification of surface geometry could also lead to counterproductive fouling results. During convective heat transfer, change in surface geometry could give rise to higher rate of fouling as long as the rate of deposition is overshadowed by lesser scale of turbulence caused by change in surface geometry. On the contrary, during pool boiling heat transfer, lower deposition rate is expected as long as both degree of turbulence and number of the nucleation sites are increased.