Characterization of continuous-flow pulsed UV light reactors for processing of liquid foods in annular tube and coiled tube configurations using actinometry and computational fluid dynamics

摘要

Pulsed UV light (PL) processing is a growing non-thermal method of treatment of solid and liquid foods. Proper design of liquid food treatment requires understanding of hydrodynamics, and PL dose distribution within the reactor. In this study, three-dimensional light energy distribution around a PL lamp was modeled based on three-parameter Gaussian model in air, model liquid foods and skim milk. Two different types of reactors, annular tube and coiled tube, are characterized based on hydrodynamics, potassium iodide-iodate based actinometry and computational fluid dynamics. Hydrodynamics result revealed a better performance of coiled tube reactor having narrower residence time distribution, secondary flow vortices and more turbulence which induce radial mixing, as opposed to axial mixing in annular tube reactor. Actinometry results showed higher PL dose (36.36-1148.63 J L-1) was absorbed in the coiled tube geometry than annular geometry (22.22-322.22 J L-1). Numerical simulations also showed a higher process uniformity in the coiled tube PL reactor.