Abstract
The purpose of this study was to develop a model to predict (1) air and product temperatures, (2) product moisture, and (3) air humidity during an aqueous coating process using a Bohle Lab-Coater. Because of the geometrical properties and the airflow, the drum of the Bohle Lab-Coater can in principle be divided into 2 zones of equal size—the drying and the spraying zones. For each zone, 4 balance equations could be set up describing the change of the air humidity, the product moisture, the enthalpy of the air, and the enthalpy of the product in each zone. For this purpose, knowledge regarding heat and mass transfer and also the motion of the tablets in drums was used. Based on the considerations of the heat and mass transfer, a set of first-order coupled ordinary differential equations (ODEs) was developed. This set of ODEs can be solved numerically. In this part, the development of the model is described in detail, whereas the application of the model can be found in part 2.
Keywords: film coating, mathematical modeling, heat and mass transfer, convection, particle movement
Full Text
The Full Text of this article is available as a PDF (352.9 KB).
References
- 1.Rowe RC. Defects in aqueous film-coated tablets. In: McGinity JW, editor. Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms. 2nd ed. New York, NY: Marcel Dekker Inc; 1997. pp. 419–440. [Google Scholar]
- 2.Franz RM, Doonan GW. Measuring the surface temperature of tablet beds using infrared thermometry. Pharm Technol. 1983;7:55–67. [Google Scholar]
- 3.Stetsko G, Banker GS, Peck GE. Mathematical modeling of an aqueous film coating process. Pharm Technol. 1983;7:50–62. [Google Scholar]
- 4.Reiland TL, Seitz JA, Yeager JL, Brusenback RA. Aqueous filmcoating vaporization efficiency. Durg Dev Ind Pharm. 1983;9:945–958. doi: 10.3109/03639048309042834. [DOI] [Google Scholar]
- 5.Rodriguez L, Grecchi R, Cini M, Passerini N, Caputo O, Vecchio C. Variation of operational parameters and process optimization in aqueous film coating. Pharm Technol. 1996;20:76–86. [Google Scholar]
- 6.Ebey GC. A thermodynamic model for aqueous film-coating. Pharm Technol. 1987;11:40–50. [Google Scholar]
- 7.Schlünder E-U, Tsotsas E. Heat Transfer in Packed Beds, in Mixed Bulks, and Fluid Beds [German] Stuttgart, Germany: Thieme Verlag; 1988. [Google Scholar]
- 8.Weiss S, Militzer K-E, Gramlich K. Thermal Process Engineering [German] Stuttgart, Germany: Deutscher Leipzig, Verlag für Grundstoffindustrie; 1993. [Google Scholar]
- 9.Schlünder E-U. Introduction in the Mass Transfer [German] Braunschweig, Germany: Vieweg Verlag; 1996. pp. 15–27. [Google Scholar]
- 10.Mellmann J. The transverse motion of solids in rotating cylinders: forms of motion and transition behavior. Powder Technol. 2001;118:251–270. doi: 10.1016/S0032-5910(00)00402-2. [DOI] [Google Scholar]
- 11.Ding YL, Forster R, Seville JPK, Parker DJ. Granular motion in rotating drums: bed turnover time and slumping-rolling transition. Powder Technol. 2002;124:18–27. doi: 10.1016/S0032-5910(01)00486-7. [DOI] [Google Scholar]
- 12.Yamane K, Sato T, Tanaka T, Tsuji Y. Computer simulation of tablet motion in coating drum. Pharm Res. 1995;12:1264–1268. doi: 10.1023/A:1016201102355. [DOI] [PubMed] [Google Scholar]
- 13.Reid RC, Prausnitz JM, Sherwood TK. The Properties of Gases and Liquids. New York, NY: McGraw-Hill; 1977. [Google Scholar]
- 14.Stahl HP. Humidity and Drying in Pharmaceutical Technology [German] Darmstadt, Germany: Steinkopff Verlag; 1980. [Google Scholar]