Authors: Paolo Casoli, Gabriele Copelli
Direct steam injection (DSI) is a sterilization technique which is often used for high viscosity fluid food when the preservation of the quality characteristics and energy efficiency are the priority. In this work an apparatus for the sterilization of tomato concentrate has been analyzed by means of multidimensional CFD (Computational Fluid Dynamics) models, in order to optimize the quality and safety of the treated food. A multidimensional two-phase model of steam injection inside a non-newtonian pseudoplastic fluid was adopted to evaluate the thermal history of the product and the steam consumption during the target process. Subsequently CFD analysis has been extended to examine the effects of the different process parameters (sterilization temperature, steam flow rate, radial and axial temperature profiles, nozzle geometry) on the resulting product. Result obtained are in agreement with available data acquired in industrial plant.