Design and efficiency evaluation of a mid-size serpentine Dean flow UV-C system for the processing of whole milk using computational fluid dynamics and biodosimetry

Abstract

UV-C processing of whole milk (WM) using a designed novel serpentine coil Dean flow system was demonstrated at flow rates of 11.88, 23.77, and 47.55 gph. Computational fluid dynamics (CFD) and biodosimetry studies were conducted to assess the flow field and fluence delivered at selected experimental flow rates. The CFD results revealed that as the flow rate increases, the ratio between average velocity to maximum velocity ( V avg /V max ) increases from 0.58 to 0.72 and enhanced Dean effects of the fluid domain at serpentine bend locations. Delivered UV fluence rate (REF rate) was 1.54 times higher at 47.88 gph than 11.88 gph. Microbial inactivation studies showed 2.75 and 4.29 log reduction (CFU/mL) of B. cereus endospores and T1UV phage after three and two passes of WM through the system at a flow rate of 47.88 gph. UV-C irradiated WM quality analysis revealed no significant effect on lipid peroxidation and volatiles profile at REF of 60 mJ/cm 2 . Lower electrical energy per order (E EO ) value also signifies the higher electrical efficiency of the system at a flow rate of 47.88 gph. • Designed and tested serpentine coiled Dean flow UV system for whole milk processing. • Demonstrated flow field at various flow rates using computational fluid dynamics. • Validated the fluence delivery and demonstrated the effect of flow rate on system's performance. • Verified microbial inactivation against bacterial endospores and virus particles. • Assessed product's quality (lipid peroxidation and volatiles profile) at different fluence levels.