Modelling the primary drying stage of the spray freeze drying process based on the non-equilibrium formulation. (1st June 2022)

• Record Type: Journal Article
• Authors: Luo, Chun; Mi, Sha; Zhou, Naijun; Liu, Zhiqiang; Cai, Lingling
• Is Part Of: International journal of heat and mass transfer. Volume 188(2022)
• Publication Date: 2022-06-01
• Subjects: Spray freeze drying -- Non-equilibrium formulation -- Primary drying stage -- Sublimation; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2022.122659
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: A mathematical model based on non-equilibrium formulation was established. The simulation results show better accordance with the experimental results compared with the model based on equilibrium formulation. The heat and mass transfer during the drying stage were analyzed. The effects of different operating parameters on the drying time were investigated. Abstract: Spray freeze drying has been expanding its influence in many fields. However, the long duration dramatically hinders its further development. A model established based on non-equilibrium formulation was established in this paper. The accuracy of the model proposed with that established based on equilibrium formulation was compared. And the history of temperature, vapor concentration and ice saturation were then investigated. Lastly, the effects of product thickness, particle diameter on the drying time were investigated. The simulation results reproduce well with the experimental data, and show a better agreement with the increase rate of experimentally measured temperature curve than that based on equilibrium formulation. In addition, the temperature increases from the bottom to the top region while the vapor concentration distribution presents the opposite trend. The ice saturation first obtains a slight increase and then decreases. Lastly, the drying time decreases as: (i) the product thickness decreases, (ii) the packing porosity increases and (iii) the chamber temperature increases. The mathematical model proposed in this paper could offer better understanding of the process and guide the design and optimization for the process.