Study On The Mechanism And Method Of Freeze Drying Of Materials In Vials

Freeze-drying as an outstanding drying method which is provided with more advantages than common drying methods has been extensively applied in many industrial productions such as pharmaceutical, food and chemical industries. The freeze drying of materials in vials is one of major forms of freeze drying production at the present time. The research of two-dimension theory that account for side heat transfer in freeze drying of materials in vials is poor. For this, following works are carried out in our laboratory as:1. The characteristics of freeze drying of materials in vials are analyzed and the literature is generalized. A comprehensive two-dimension model has been constructed using the theory of heat and mass transfer. According to characteristics of model's equations, two cycles' symmetry spit method, predict-correct method, etc., are combined to solve the model numerically.2. The experiments of freeze drying of skim milk in vials have been carried out on DF-01H Freeze Drier in the presence of HP3054A Data Acquisition And Control System et al. The experimental curves of temperature and remaining water content are compared with modeling results, and the agreement between the experimental data and modeling results is quite good.3. The effect of side heat transfer on freeze drying process is investigated by testing and simulating. The results show that the effect of side heat transfer on the freeze drying process of materials in vials can not be ignored in realistic production and the change of material temperature distribution caused by side heat transfer must be considered in the operation and control of freeze drying process. The effect extent of side heat transfer is related to the thickness of material, vial diameter, emissivity of heating and radiating plates, chamber pressure, temperatures of heating and radiating plates. The first to forth one among the parameters mentioned...