Microwave is used as th heat source for freeze-drying process and the unsteady-state behavior of spherical model is analysed numerically. the Crank Nicolson method is used to solve the transient energy and mass transfer equations in both ice core and dried layer. A mathematical model is used to simulated the freeze-drying of beef meat.
The drying time decreases as the electric field stength increases. The drying time decreases as the pressure of vacuum chamber increases to 5-10 mmHg, at which the minimum drying time occurs. And further increase of the vacuum chamber pressure results in the increase of the drying time. It has also been found that ambient temperature, partial pressure of water vapor in the vacuum chamber, and sample radius directly affect the dryng time.