Stability of nonfouling stainless steel heat exchanger plates against commercial cleaning agents

• A bench scale miniature heat exchanger with shear and wall heating effects was designed.
• Alkali detergent did not significantly alter surface chemistry, topography, or hydrophobicity.
• Acid sanitizer significantly altered surface chemistry, topography, and hydrophobicity.
• Modified stainless steel retained non-fouling character after exposure to alkali detergent.

Electroless nickel-PTFE coatings were applied to heat exchanger plates to reduce food material fouling and lessen the impact on heat transfer rate and operating efficiency. Clean-in-Place procedures are performed after each processing run with an alkali detergent and acid sanitizer to remove fouling material and sanitize. Understanding the impact of such cleaners on the coating integrity is critical in demonstrating the commercial suitability for food processing applications. XPS, dynamic contact angle, optical profilometry, SEM, and a custom fabricated benchtop plate heat exchanger were used to quantify changes to surface chemistry, topography, and the non-fouling properties after exposure to the chemical cleaners. Insignificant changes were observed after alkali detergent exposure while the acid sanitizer significantly affected the surface coating. The effects of the cleaners were further observed during the fouling experiments with the alkali detergent retaining the non-fouling properties and the acid sanitizer showing an increase in fouling material accumulation.