Heat Transfer and Simulated Sterilization of Particulate Solids in a Continuously Flowing System

The heat transfer coefficients (h) between a cube and water were 239 and 303 W/m 2 K at 0 and 0.86 cm/s relative velocity. In 35% sucrose and 0 cm/sec, h was 146 W/m 2 K. A model for heat lethality in cubes during continuous sterilization which used finite difference equations for heat conduction and above values of h, revealed that hold times for 6D inactivation of PA 3679 (F 0 = 7.2 min) in an isothermal fluid at 132.2°C were 1.78 and 5.2 min for 1 and 2 cm cubes when h was 303 W/m 2 K and 1.23 and 4.13 min when h was 2500 or higher. When h was 239 W/m 2 K, hold times were 2.36 and 6.02 min for 1 and 2 cm cubes. When fluid entered the hold tube at 132.2°C and particle to fluid ratio was 0.56, fluid‐particle heat exchange increased hold time to 12.2 and 119 min for 1 and 2 cm cubes.