Heat transfer in a plate exchanger during pasteurization of orange juice

The heat transfer film coefficient of orange juice (OJ) during pasteurization using a plate heat exchanger with intermating 316 SS plates was studied. Mathematical models to predict OJ heat transfer film coefficient are presented. The OJ density was measured using an in-line density sensor at pasteurization temperature and also measured off-line by hygrometer at different temperatures. The OJ viscosity was measured by an off-line instrument, in the temperature range from 5-90 degrees C. The mean values of OJ density and OJ viscosity at 20 degrees C were 1046.0 +/- 3.6 kg/m(3) and 14.17 +/- 4.75 mPa s, respectively. The values of heat transfer film coefficient for OJ varied from 983 to 6500 W/m(2) degrees C, whereas the water heat transfer film coefficient varied from 8387 to 24245 W/m(2) degrees C. This study has provided a suitable heat transfer correlation to predict the OJ heat transfer film coefficient as a function of its viscosity and the channel velocity, that is, this correlation is independent of the plate geometry, for varied conditions of OJ pasteurization process. (C) 1999 Elsevier Science Ltd. All rights reserved.