Antifouling heat exchangers will make cleaning easier

Biofilms — the scourge of food processors — can easily persist in heat exchangers. A few microbes get stuck in the grooves and recesses of the heat exchanger and before you know it they form a sticky residue or biofilm that serves as a reservoir of bugs that contaminate the liquid foodstuffs that are being processed.

To overcome this risk heat exchangers must be thoroughly cleaned at regular intervals. This process could soon be a lot easier.

The INM – Leibniz Institute for New Materials is investigating the use of nanocoatings in reducing the effort required to clean heat exchangers. The nanocoatings have an anti-adhesive and antimicrobial effect and heat exchangers coated with these paints require intensive cleaning far less often.

To prevent microbes, bacteria or fungus from adhering to surfaces, the scientists use colloidal copper in the coating. Due to the oxygen or water that is present in many foodstuff processes, copper ions are created from the copper. These travel to the surface and, as a result of their antimicrobial effect, they prevent microbes from settling there. The developers achieve the anti-adhesive characteristics by introducing hydrophobic compounds that are similar to common Teflon. These prohibit the formation of any undesired biofilm and allow residues to be transported out more easily before they clog up the channels of the heat exchangers.

“In addition, we can keep the paint chemically stable. Otherwise it would not withstand the aggressive chemicals that are required for cleaning,” explained Carsten Becker-Willinger, head of nanomers at INM. Adding that the paint could also be adapted for special mechanical loads, he explained that this was important for paint used in heat exchangers, too. Due to mechanical vibrations, the individual plates of the heat exchangers could be subjected to a certain amount of abrasion at points of contact.

Principally, the paint developed could also be used in other contexts, Becker-Willinger said, including the large sector of air conditioning with heat exchangers. Furthermore, the paint could be used for cleaning wastewater in water purification plants, for example, to prevent biofilm from accumulating on filters or tubes.

The paint can be applied using standard methods such as spraying or immersion and subsequent hardening. It can be used on stainless steel, alloys, titanium or aluminium.

The developers will be demonstrating their results and the possibilities they offer at stand B46 in hall 2 at this year’s Hanover Trade Fair as part of the leading trade show Research & Technology, which takes place from 25 to 29 April.