Time-Dependent Heat Transfer Coefficients of Standard Cans during Pasteurization.

Abstract

Canned food products are pasteurized by heating them in hot water to deactivate enzymes, followed by rapid cooling. We utilized computational fluid dynamics (CFD) to analyze heat transfer in juice cans of 330 mL, 500 mL, and 1000 mL placed in water baths set at 60 °C, 80 °C, and 25 °C. Two methods were employed to study heat transfer: a detailed conjugate heat transfer simulation and a simplified boundary condition approach that applies time-averaged heat transfer coefficients to the can wall without modeling the surrounding bath fluid. The conjugate heat transfer simulation's time-temperature profile aligned with experimental results within a 2% margin. The three stages of heat transfer during heating and cooling cycles significantly affected the profile inside the sealed container, making this simulation essential for determining effective pasteurization come-up times. Results indicated that the heat transfer coefficients on both the inner and outer surfaces were nearly identical during heating and cooling. The temperature contours inside the container showed spatial patterns similar to those in both cycles. As expected from natural convection effects, a cold spot was consistently found near the bottom and a hot spot was consistently found near the top. Additionally, increasing the water bath temperature from 60 to 80 °C can shorten come-up times by 12-15%.