Natalia Menshutina

Dynamic analysis of drying energy consumption

Abstract A concept of instantaneous drying and energy efficiencies has been applied to analyze energy consumption in a through-circulation conveyor dryer and a batch fluid bed dryer for synthetic rubber. It is shown that the energy performance of the conveyor dryer can be improved by leveling of the moisture content distribution across the material layer by mechanical agitation, and sectioning of the air plenum in order to reduce inlet air temperature in the last two sections of the dryer. It is also shown that drying of a synthetic rubber in the fluid bed dryer is more energy-efficient than in the conveyor dryer, especially in the constant-rate period. Thus, the largest energy savings could be obtained in a two-stage dryer comprised of the plug-flow fluid bed dryer, and the belt conveyor dryer for removal of the bulk and residual water, respectively. #© Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources, 2004.

Spray Drying of Probiotics: Process Development and Scale-Up

Spray drying is an alternative method to freeze drying of Bifidobacterium bifidum biomass during the production of solid dosage forms. In order to develop a new drying process for probiotics and to establish the generalized mathematical model for the proposed technology, both experimental and theoretical studies on B. bifidum biosuspension have been carried out. These studies focused on drying kinetics, kinetics of cell death due to thermal shock and growth of osmotic pressure; on defining the influence of process parameters on product quality; and on identifying the limitations of process parameters due to material characteristics. Based on experimental data and modeling results, recommendations for organization of industrial process have been provided.

3D Reversible Cellular Automata for Simulation of the Drug Release from Aerogel-Drug Formulations

Abstract According to the recent investigations great attention is paid to using high porosity bodies like aerogels as drug delivery systems. Being nontoxic and environmental friendly they have high potential to be applied in pharmaceutics. Modeling of drug release process from aerogel-drug formulations by means of cellular automata with Margolus neighborhood is presented in this paper. Margolus cellular automata have an important property of microscopic reversibility as well as real diffusion process. To apply this method high computational power is required. Special computer with parallel calculations based on CUDA technology was designed for this purpose.

3D Cellular automata for modeling of spray freeze drying process

This paper presents a cellular automata modeling of the atmospheric freeze drying process with active hydrodynamics. Presented approach makes possible to calculate drying kinetics taking into account internal structure of a particle, as well as heat and mass transfer and phase changes. nVidia CUDA technology and high-performance computer with parallel computing were used for model calculations.

General-purpose graphics processing units application for diffusion simulation using cellular automata

An approach to use general-purpose graphics processing units (GPGPU) using nVidia CUDA technology1 to increase the performance of cellular automata is presented in this paper. Shown that the calculations on the GPU faster (more than one order of magnitude) in comparison with CPU calculations and a well-functioning C-code. Cellular automata with Margolus’ neighborhood are used for the demonstration of general steps in CUDA simulations.

Quality by design approach in drying process organization

Abstract With the rapid implementation of the PAT initiatives, the role of quality control systems in pharmaceutics is going to be extremely important. The operation of such systems is closely connected with the use of various mathematical methods and information technologies directed to the achievement and maintaining required quality at every step of the production process and therefore guarantee the quality of final product. This forms a base for quality by design approach in process organization. This paper presents an approach to process organization using PAT and design of information system that can be capable to use and process data from different production levels and therefore provide production process monitoring and control. Three technological processes, with drying stage included (freeze-drying, granulation, coating) is taken as an example of the described approach application.

Design of a Kinetic Model for Degradation of Substances During Spray Drying Using Yeast Biosuspension, Oil-in-Water Emulsion, and Alumosilicate Suspension

Spray drying is a widespread technology for the dehydration of materials with a high initial content of solvent in order to improve product stability during storage, simplify batching, and reduce transportation costs. The high rate of evaporation, contact with oxygen in the air, as well as overheating of the material in the case of unacceptable process conditions can lead to the destruction of valuable components, their oxidation, and loss of volatile substances. The article presents an approach to determine the kinetics of degradation of the substances as a function of the current state of the material (temperature, residual moisture content, and rates of changes) during the spray-drying process. It was shown that this approach can be applied to various types of materials with different properties. The obtained kinetic equations were used to predict the quality of product dried in pilot-scale spray equipment.

System approach to modeling of pharmaceutical integrated processes: drying, layering and coating

Abstract The paper concerns the system approach to modeling of pharmaceutical technology of drying, layering and coating in fluidized bed apparatus. The mathematical modeling bases on the statistical method for micro-level phenomena description and on heterogeneous media mechanics and non-equilibrium thermodynamics for macro-level description.

Prediction of structure changes of organic-silica aerogels during pyrolysis

Abstract Silicon-carbon composites (Si-C composites) can be produced by the pyrolysis of silicon-organic materials including silica-formaldehyde-resorcinol aerogels (Si-F-R aerogel). During the pyrolysis process such structures characteristics as pore size distribution, specific surface area, total pores volume and micropores volume usually change significantly. In this paper, the cellular automata (CA) approach has been used to predict structure changes. Two methods for virtual structure formation of raw organic-silica materials have been developed: 1) a simplistic method for 2D structure generation where the pores are cylindrical and straight without branches; 2) diffusion limited aggregation method with multiple centers (multi-DLA) for 3D structure generation. Additionally, a probabilistic CA has been developed in order to simulate the pyrolysis process.

Prediction of the Solubility in Supercritical Carbon Dioxide: a Hybrid Thermodynamic/QSPR Approach

Abstract Numerous studies are devoted to the experimental investigation of equilibria in supercritical fluids (SCFs), in particular to the problem of solubility. However, prediction of the solubility entirely based on molecular structure still remains challenging. The aim of this contribution is two-fold. First, we present a compendium of solubility data for high-boiling point compounds in supercritical carbon dioxide and its mixtures with modifiers. Literature data from late 70s till present were collected from more than 300 original publications ( ca . 600 compounds, more than 20,000 experimental points). The data are organized in a database that offers diverse functionality. Second, we exemplify the usage of the database by prediction of the solubility employing two models, semi-empirical Chrastil model and more physically sound regular solution model. Both models ultimately require empirical parameters which were related to the molecular structure of the solute (quantitative structure – property relationship, QSPR). Presented hybrid thermodynamic/QSPR approach allows to exceed the limits of the experimental data and to predict the solubility at given pressure and temperature based entirely on molecular structure.