Abstract
To investigate the enhanced impact of initially porous frozen
material and wave-absorptive medium-assisted microwave heating on traditional freeze-drying, a multiphysics model coupling temperature, concentration,
and electric fields was formulated and numerically solved, and microwave
freeze-drying experiments of aqueous mannitol solution were conducted with
silicon carbide as the wave-absorptive medium. The results demonstrated that
the use of porous frozen material and wave-absorptive medium could
dramatically enhance the microwave freeze-drying process. Under 30 °C and
22 Pa of the tested conditions, the microwave freeze-drying time spent for the
initially porous sample can be 18 and 30%, respectively, shorter than traditional
freeze-drying times for porous and solid samples. Excellent accordance was
achieved between simulated and measured drying curves. Based on the profiles
of temperature, saturation, and electrical field strength, mechanisms of mass
and heat transfer, as well as propagation and dissipation of electromagnetic
wave within a sample, were analyzed during drying. There were similar quantities of cumulatively absorbed energy for traditional
freeze-drying of solid and porous samples and microwave freeze-drying of porous samples. Theoretical and experimental results
indicated that the proposed method can significantly increase the freeze-drying rate and improve the process economy.
material and wave-absorptive medium-assisted microwave heating on traditional freeze-drying, a multiphysics model coupling temperature, concentration,
and electric fields was formulated and numerically solved, and microwave
freeze-drying experiments of aqueous mannitol solution were conducted with
silicon carbide as the wave-absorptive medium. The results demonstrated that
the use of porous frozen material and wave-absorptive medium could
dramatically enhance the microwave freeze-drying process. Under 30 °C and
22 Pa of the tested conditions, the microwave freeze-drying time spent for the
initially porous sample can be 18 and 30%, respectively, shorter than traditional
freeze-drying times for porous and solid samples. Excellent accordance was
achieved between simulated and measured drying curves. Based on the profiles
of temperature, saturation, and electrical field strength, mechanisms of mass
and heat transfer, as well as propagation and dissipation of electromagnetic
wave within a sample, were analyzed during drying. There were similar quantities of cumulatively absorbed energy for traditional
freeze-drying of solid and porous samples and microwave freeze-drying of porous samples. Theoretical and experimental results
indicated that the proposed method can significantly increase the freeze-drying rate and improve the process economy.
| Original language | English |
|---|---|
| Pages (from-to) | 20903-20915 |
| Journal | INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH |
| Volume | 59 |
| Issue number | 47 |
| DOIs | |
| Publication status | Published - 23 Oct 2020 |