Heat and mass transfer study in the spray drying of tomato juice

Spray drying is a procedure which is now used for a wide range of applications ranging from food products to chemicals. In this work, a co-current spray dryer is used and the tomato juice feed is initially heated to a temperature of 60 degrees C. Also, pressurized nitrogen gas is used for atomizing the feed and thereby improving the performance of the spray dryer. Experiments have been performed at different inlet air temperatures while the other parameters like air flow rate, feed flow rate and feed temperature are maintained essentially constant. Through this study, it is found that immediately after the atomized feed are exposed to the drying medium, the relative humidity of the drying air reaches a maximum (99.99% RH), remains constant during the spray time and then decreases when the spray time is over. It is also found that, as the inlet air temperature is varied from 133 degrees C to 161 degrees C, there is an increase of 11.62% in heat transfer rate and a marginal increase of 0.51% in mass transfer rate.