Numerical Investigation on Dielectric Material Assisted Microwave Freeze-Drying of Aqueous Mannitol Solution

Abstract The dielectric material assisted microwave freeze-drying was investigated theoretically in this study. A coupled heat and mass transfer model was developed considering distributions of the temperature, ice saturation and vapor mass concentration inside the material being dried, as well as the vapor sublimation-desublimation in the frozen region. The effects of temperature and saturation on the effective conductivities were analyzed based on heat and mass flux equations. The model was solved numerically by the variable time-step finite-deference technique with two movable boundaries in an initially unsaturated porous sphere frozen from an aqueous solution of mannitol. The sintered silicon carbide (SiC) was selected as the dielectric material. The results show that dielectric material can significantly enhance microwave freeze-drying process. For case of the dielectric field strength, E = 4000 V/m under typical operating conditions, the drying time is 2081 s, 30.1% shorter and 47.2% longer, respectively, than those for E = 2000V/m and E = 6000 V/m. The heat and mass transfer mechanisms during the drying process were discussed.

[1]  J. D. Ford,et al.  Microwave freeze drying: An experimental investigation , 1977 .

[2]  Z. Wang,et al.  The effects of sublimation-condensation region on heat and mass transfer during microwave freeze drying , 1998 .

[3]  J. P. Dolan.  Use of Volumetric Heating to Improve Heat Transfer During Vial Freeze-Drying , 1998 .

[4]  Y. Ma,et al.  Aerosol Formation During the Microwave Freeze Dehydration of Beef , 1985, Biotechnology progress.

[5]  Yi Hua Ma,et al.  Freeze dehydration by microwave energy: Part I. Theoretical investigation , 1975 .

[6]  Sui Lin.  An Exact Solution of the Sublimation Problem in a Porous Medium, Part II—With an Unknown Temperature and Vapor Concentration at the Moving Sublimation Front , 1982 .

[7]  Robert C. Weast Jeanette G Grasselli David R. Lide,et al.  Handbook of data on organic compounds , 1994 .

[8]  E. P. Scott.  An Analytical Solution and Sensitivity Study of Sublimation-Dehydration Within a Porous Medium With Volumetric Heating , 1994 .

[9]  M. Boles,et al.  Analytical study of vacuum-sublimation in an initially partially filled frozen porous medium with recondensation , 1988 .

[10]  M. Pikal,et al.  Physical chemistry of freeze-drying: measurement of sublimation rates for frozen aqueous solutions by a microbalance technique. , 1983, Journal of pharmaceutical sciences.

[11]  Michael J. Pikal,et al.  The secondary drying stage of freeze drying: drying kinetics as a function of temperature and chamber pressure☆ , 1990 .

[12]  Y. Ma,et al.  Simulation of a Combined Microwave and Radiant Freeze Dryer , 1990 .

[13]  J. D. Ford,et al.  Microwave freeze-drying of food: A theoretical investigation , 1977 .

[14]  A. V. Lykov.  On systems of differential equations for heat and mass transfer in capillary porous bodies , 1966 .

[15]  M. Boles,et al.  An analytical study of the effect of convection heat transfer on the sublimation of a frozen semi-infinite porous medium , 1987 .

[16]  James P Dolan.  Microwave freeze-drying of aqueous solutions , 1994 .

[17]  Sui Lin.  An Exact Solution of the Sublimation Problem in a Porous Medium , 1981 .

[18]  R. Munro.  Material Properties of a Sintered α-SiC , 1997 .

[19]  A. Luikov.  SYSTEMS OF DIFFERENTIAL EQUATIONS OF HEAT AND MASS TRANSFER IN CAPILLARY-POROUS BODIES (REVIEW) , 1975 .

[20]  A. I. Liapis,et al.  OPTIMAL CONTROL OF THE PRIMARY AND SECONDARY DRYING STAGES OF BULK SOLUTION FREEZE DRYING IN TRAYS , 1998 .

[21]  M. Boles,et al.  EFFECT OF MASS CONVECTION ON VACUUM-SUBLIMATION IN AN INITIALLY PARTIALLY FILLED FROZEN POROUS MEDIUM , 1988 .

[22]  Y. Ma,et al.  Freeze dehydration by microwave energy: Part II. Experimental study , 1975 .

[23]  Z. Wang,et al.  Numerical study on sublimation–condensation phenomena during microwave freeze drying , 1998 .

[24]  Y. C. Fey,et al.  The parametric analysis of self-freezing in an initially wet porous medium , 1988 .

[25]  George W. A. Milne,et al.  CRC Handbook of Data on Organic Compounds , 1993 .

[26]  Michael J. Pikal,et al.  The collapse temperature in freeze drying: Dependence on measurement methodology and rate of water removal from the glassy phase , 1990 .

[27]  R. Bruttini,et al.  Freeze-Drying of Pharmaceutical Crystalline and Amorphous Solutes in Vials: Dynamic Multi-Dimensional Models of the Primary and Secondary Drying Stages and Qualitative Features of the Moving Interface , 1995 .

[28]  M. Maeda,et al.  [Heat conduction]. , 1972, Kango kyoshitsu. [Nursing classroom].

[29]  Sui Lin.  An exact solution of the desublimation problem in a porous medium , 1982 .

[30]  Hasan Sadikoglu,et al.  Mathematical Modelling of the Primary and Secondary Drying Stages of Bulk Solution Freeze-Drying in Trays: Parameter Estimation and Model Discrimination by Comparison of Theoretical Results With Experimental Data , 1997 .

[31]  Y. C. Fey,et al.  An Analytical Study of the Effect of the Darcy and Fick Laws on the Sublimation of a Frozen Semi-infinite Porous Medium , 1987 .

[32]  Mohammed M. Farid,et al.  Analysis of Heat and Mass Transfer in Freeze Drying , 2003 .