Mathematical modeling and simulation of suspension droplet drying

Özcan, Ahmet Furkan
Drying procedures like spray drying, fluidized bed drying etc. are widespread industrial applications. Such procedures mainly aim to produce high value pharmaceuticals and bulk commodities such as dried milk and detergent powders, which require controlled physical properties that are dependent on the drying process that they are subject to. The aim of this study is to model the kinetics of water droplet drying containing nanosized SiO2 particles and simulate the coupled heat and mass transfer processes via a computer program. The main physical mechanisms involve initial transfer of heat by convection from flowing air with constant properties and then thermal conduction and evaporation of water from the liquid interface, simultaneous diffusion of liquid and nanoparticles leading to agglomeration of solid particles near liquid interface and eventually formation of a shell structure, while a shrinkage in droplet size occurs. As the wet shell region widens with adhering nanoparticles from the inner region, at a certain point shell strength becomes able to sustain the capillary forces exerted by receding water and consequently solid particles in the shell region ceases to recede. Beyond this point, liquid interface recedes towards the center as water evaporation still continues through the pores of the dry crust region, which was a part of former wet shell itself. On the other hand, transfer diffusion of water molecules at the center of the particle towards the evaporation front causes a vacant region to form in the middle, provided that initial amount of solid particles is not sufficient to fill the entire volume of the dried structure. The essential focus in this study is on the kinetics of suspension droplet drying after the liquid interface recedes behind solid particles, namely the dry crust. Eventually all water molecules evaporate from the inner region of the particle leading to either a solid or hollow particle morphology depending on the initial solid fraction.


Evaluation of solar sludge drying alternatives on costs and area requirements
Kurt, Mayıs; Aksoy, Ayşegül; Sanin, Faika Dilek; Department of Environmental Engineering (2014)
There are basically two common sludge drying methods, thermal drying and solar drying. While thermal drying requires high amount of energy, solar drying cannot typically attain the 90 % DS requirement. The literature studies emphasize the benefits of solar drying used as GSD (greenhouse solar dryer) to reduce energy requirement but these dryers cannot achieve 90 % DSC without any auxiliary heat. Therefore, use of solar panels as auxiliary heat source was evaluated in this study. To calculate how much energy...
Investigation of parameters affecting the drying rate of sanitary wares
Güngör, Ergin; Güngör, Ergin; Department of Metallurgical and Materials Engineering (2005)
The influence of drying parameters namely residence time before drying, drying temperature, drying time, relative humidity, and slip recipe on the drying rate of slip cast sanitary wares, predominantly lavatories and toilet closets, was studied. The drying temperatures were changed from 80 oC to 110 oC with an increment of 10 oC. The drying time was changed from 10 to 7 h with a decrease of 1 hour. Relative humidity of the environment was changed from 60 to 75 %. The percent weight loss, percent residual mo...
Mathematical modeling of survival and weight loss of Baker's yeast during drying
Alpas, Hami; BOZOGLU, F; KATNAS, S (1996-10-01)
Drying and death rates of Baker's yeast were studied in a computer-controlled laboratory scale tunnel drier with varying air velocity between 2.0-3.0 ms-1 and temperatures within the range of 40-60 degrees C. Two falling rate periods were observed during the drying process. A single first-order expression described the death rate of the microorganisms during both drying phases. Arrhenius-type expressions described the effects of the temperature on the first falling rate period drying and death rate constant...
Evaluation of solar sludge drying alternatives by costs and area requirements
Kurt, Mayis; Aksoy, Ayşegül; Sanin, Faika Dilek (2015-10-01)
Thermal drying is a common method to reach above 90% dry solids content (DS) in sludge. However, thermal drying requires high amount of energy and can be expensive. A greenhouse solar dryer (GSD) can be a cost-effective substitute if the drying performance, which is typically 70% DS, can be increased by additional heat. In this study feasibility of GSD supported with solar panels is evaluated as an alternative to thermal dryers to reach 90% DS. Evaluations are based on capital and O&M costs as well as area ...
Sensitivity Analysis of Distortion of Carburized Steel Shafts Using Computer Simulations
Yazır, Büşra; Evcil, Elif; Yıldız, Seçil; Davut, Kemal; Şimşir, Caner (null; 2016-12-01)
Carburizing and subsequent quenching heat treatments are commonly used industrial processes to improve the properties and performance of steel shafts. Undesired dimensional and shape changes (distortion) related to these treatments are still the most frequent reason for expensive and time consuming corrective operations, low performance during service and even product rejection. The major aim of this study is to identify the suitable control parameters for subsequent optimization of the carburized quenching...
Citation Formats
A. F. Özcan, “Mathematical modeling and simulation of suspension droplet drying,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Chemical Engineering., Middle East Technical University, 2019.