Abstract
The heat transfer ®lm coecient 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 ®lm coecient are presented. The OJ density was measured using an in-line density sensor at pasteurization temperature and also measured o-line by hygrometer at dierent temperatures. The OJ viscosity was measured by an o-line instrument, in the temperature range from 5±90°C. The mean values of OJ density and OJ viscosity at 20°C were 1046.03.6 kg/m3 and 14.174.75 mPa s, respectively. The values of heat transfer ®lm coecient for OJ varied from 983 to 6500 W/m2 °C, whereas the water heat transfer ®lm coecient varied from 8387 to 24245 W/m2 °C. This study has provided a suitable heat transfer correlation to predict the OJ heat transfer ®lm coecient 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. Ó 1999 Elsevier Science Ltd. All rights reserved