A New Route Combining Direct-Contact Evaporation and Vapor Permeation for Obtaining High-Quality Fruit Juice Concentrates. Part II: Modeling and Simulation

A mathematical framework is presented for simulating each step of the proposed juice-processing route. Both the gas stripper and the direct-contact evaporator were simulated by combining a transient, well-mixed model for the liquid phase with a detailed model for heat and multicomponent mass transfer in superheated bubbles that was previously developed. For vapor permeation, a multicomponent, one-dimensional, plug-flow model for a hollow-fiber module was developed, considering both countercurrent and cocurrent configurations. These models were tested against experimental data. A sensitivity analysis of the proposed route was also conducted considering two main operation parameters: evaporator and permeate pressures. When the former was reduced, a significant drop in the liquid temperature in tandem with an augmentation of the evaporation rate was observed, whereas an increase in the latter led to a lower recovery degree in the membrane module.