Performance evaluation of a baffled rotating contactor for the concentration of fruit juice by air stripping

Abstract Simultaneous heat and mass transfer experiments with air–water system were performed in a baffled rotating contactor and volumetric mass transfer coefficient determined towards exploring an alternate strategy for the concentration of fruit juice. The proposed concentration technology is based on the stripping of water from fruit juice by an unsaturated gaseous stream. In the contactor, the phases flowed counter-currently between two rotating circular disks zigzagging across concentric circular baffles fitted in the inner surface of the disks. The volumetric mass transfer coefficient varied between 7 kg/m3s to 20 kg/m3s for the range of operating conditions studied. The evaporation rate of water per unit volume was higher than in falling film type evaporators used conventionally for the concentration of fruit juice. The maximum concentration of orange juice attained in the rotating contactor within two hours with continuous recirculation of the solution was 32.6 °Brix for the operating conditions studied. This was significantly higher than that obtained in a rotating packed bed contactor of similar volume (2.0 L).