Experimental and simulation studies of primary vacuum freeze-drying process of random solids at microwave heating

✍ Scribed by J.F. Nastaj; K. Witkiewicz; B. Wilczyńska

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 591 KB
• Volume: 35
• Category: Article
• ISSN: 0735-1933
• DOI: 10.1016/j.icheatmasstransfer.2007.09.003

✦ Synopsis

This paper concerns experimental and theoretical studies of freeze-drying process at microwave heating. Two kinds of random solids were dried: material which are assumed to have no internal porosity (ground glass), as well as one containing internal porosity (Sorbonorit 4 activated carbon). Formulated one-dimensional two-region model of freeze-drying process at microwave heating takes into account unknown a priori sublimation temperature T s (t) and mass concentration of water vapor C s (t) at moving ice front. Steady capacity of internal heat source is correlated with electric field strength E and dissipation coefficient K(T) in both regions of the material to be dried. Linear temperature dependency of dissipation coefficient is assumed and described by two regression parameters: μ 1 i and μ 2 i for dry (i = I) and frozen (i = II) bed, respectively. A correlation between both measured and calculated temperatures of the sample and actual electric field strength was observed. Fairly good agreement between experimental and simulated results was stated.