**3.3 Effects produced by biofouling in heat exchangers**

Biofouling has a great influence on the thermal performance of heat exchangers, due to the accumulation of biotic deposits with insulating characteristics in heat exchange surfaces. This accumulation adds not only an additional thermal resistance to the flow of heat but a greater frictional resistance to the passage of the fluid. The formation of these biofilms produces important modifications, since they alter the physical–chemical conditions at the metal-solution interface and form barriers for the exchange of elements between the metallic surface and the surrounding liquid medium [64]. Among the negative consequences, the decrease of the heat output of the heat exchangers and the lower durability of the construction materials of the equipment can be mentioned [65].

The main consequences produced by microfouling (biofouling) in heat exchangers are the following [5]:


The main consequences of macrofouling in a heat exchanger are [40]:

