Numerical simulation of heat and mass transfer during sublimation drying of porcine aorta

Abstract

Freeze-drying is an effective method for aortal preservation. However, there are few studies on heat and mass transfer of aortal freeze-drying. In this study, the contactless weighing device was used to monitor freeze-drying process. The radiation view factor of the aortal segment was estimated, and the quasi-steady state model was used to analyze heat and mass transfer, there was a certain amount of heat flux in the frozen layer, which provided sublimation heat for internal sublimation interface. By theoretical calculation, the vapor diffusion coefficient was determined. The unsteady state model was used for numerical simulation. The simulated result of free water removal ratio was consistent with experiment result. Both heat flux density and mass flux density decreased non-linearly in the early stage, but approximately linearly in the late stage. The velocity of inner and outer sublimation interfaces was almost the same. The nodes temperature gradually increased and finally approached the heating temperature, and the temperature gradient of both dried and frozen layers decreased gradually with drying time. The water vapor pressure gradient was smaller near the aortal wall and larger in the middle region.

Keywords:

• Freeze-drying
• sublimation
• numerical simulation
• heat and mass transfer
• diffusion coefficient

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Notes on contributors

Chao Gui

Chao Gui, Ph.D. Candidate, the major research are refrigeration technique and cryobiomedical technique.

Leren Tao

Leren Tao, professor, the major research includes refrigeration technique, cryobiomedical technique, power engineering and engineering thermophysics.

Weifang Yang

Weifang Yang, lecturer, the major research are refrigeration technique and heat transfer enhancement technology.

Yaqi Zhang

Yaqi Zhang, master candidate, the major research are refrigeration technique and cryobiomedical technique.

Shanshan Chen

Shanshan Chen, Ph.D. Candidate, the major research are refrigeration technique and cryobiomedical technique.

Daoming Shen

Daoming Shen, doctor, the major research are refrigeration technique and heat transfer enhancement technology.

Lele Yang

Lele Yang, master candidate, the major research are refrigeration technique and cryobiomedical technique.