Mitigation of calcium sulphate fouling in a stainless-steel tube heat exchanger using titanium oxide coating: An experimental and numerical study with economic and environmental implications

Crystallization fouling is a major cause of decreased thermal efficiency and operational life of heat exchangers, especially in water-based systems. Therefore, this study examines the prevention of calcium sulfate (CaSO 4 ) fouling in a stainless-steel tube heat exchanger using a titanium oxide (TiOx) coating deposited through physical vapor deposition (PVD). Under controlled thermal and flow conditions, experimental testing was performed using a supersaturated solution of CaSO 4 . Over a 6-day period, foulant deposition and heat transfer performance were assessed. Additionally, a CFD model has been made to perform numerical analysis of the system in bare and fouled conditions. The results revealed that TiOx coating decreased the fouling mass deposition by a significant amount of 29.5%, increased the induction time by 2.75 times and augmented thermal performance with asymptotic fouling resistance being 44% less than uncoated counterpart. Economic and environmental assessment suggested that the possible economic savings may reach up to 1838 USD/MW, as well as CO 2 emission cut by 0.8 tons/MW, which demonstrates the efficiency of the coating in improving the sustainability of the heat exchanger.