Computer simulations drying

The rate of convective drying depends on the temperature of the drying medium, its humidity, and fiow rate. In computer-simulated drying processes based on mathematical models, the temperature and humidity of the drying medium can be controlled directly, but the gas velocity is adjusted indirectly... 

Figure 62.15 presents computer-simulated drying curves, that is, the decrease of average moisture contents in a dried body versus time for different temperatures and absolute humidity of a drying medium (Table 62.1). 

The main conclusion which can be drawn from the results presented above is that dimerization of particles in a Lennard-Jones fluid leads to a stronger depletion of the proflles close to the wall, compared to a nonassociating fluid. On the basis of the calculations performed so far, it is difficult to conclude whether the second-order theory provides a correct description of the drying transition. An unequivocal solution of this problem would require massive calculations, including computer simulations. Also, it would be necessary to obtain an accurate equation of state for the bulk fluid. These problems are the subject of our studies at present. 

Figure 8 An example of the decreasing heat requirement during primary drying at a chamber pressure of 0.15 torr. 5% mannitol maintained at -20°C during primary drying. Results obtained by computer simulation of freeze drying (see Ref. 3). Heavy curve Shelf Fluid. Light curve Shelf surface. Lightweight dashed curve Product Bottom. Heavy dashed curve Sublimation.

MJ Pikal. Use of laboratory data in freeze drying process design Heat and mass transfer coefficients and the computer simulation of freeze drying. J Parenter Sci Tech-nol 39 115-138, 1985. 

Simulations of three representative Cs-smectites revealed interlayer Cs+ to be strongly bound as inner sphere surface complexes, in agreement with published bulk diffusion coefficients [78]. Spectroscopic and surface chemistry methods have provided data suggesting that in stable 12.4 A Cs-smectite hydrates the interlayer water content is less than one-half monolayer. However, Smith [81] showed using molecular simulations of dry and hydrated Cs-montmorillonite that a 12.4 A simulation layer spacing was predicted at about one full water monolayer. The results of MD computer simulations of Na-, Cs-and Sr-substituted montmorillonites also provide evidence for a constant water content swelling transition between one-layer and two-layer spacings [82]. 

F. van Swol and J. R. Henderson, Wetting and Drying at a Fluid-Wall Interface. Density-Functional Theory versus Computer Simulation, Phys. Rev. A 43 (1991) 2932-2942 Wetting at a Fluid-Wall Interface, J. Chem. Soc. Faraday Trans. 2 82 (1986) 1685-1699 Complete Wetting in a System with Short-range Forces, Phys. Rev. Lett. S3 (1984) 1376-1378. 

FIGURE 14 Computer simulation of bench scale spray drying process 3D, turbulent flow with multi-phase heat and mass transfer simulation. 

FIGURE 16 Calculated liquid droplet temperature based upon computer simulation of multiphase drying process. do = S pm. solids = 1.5% (m/v) (note that falling rale period is not modeled). 

Friedman and Mahall, Studies in Rotary Drying. Part 1. Holdup and Dusting. Part 2. Heat and Mass Transfer, Chem. Eng. Progr, 45 482-493,573-588 (1949). Hirosue and Shinohara, Volumetric Heat Transfer Coefficient and Pressure Drop in Rotary Dryers and Coolers, 1st Int. Symp. on Drying, 8 (1978). Kamke and Wilson, Computer Simulation of a Rotary Dryer. Part 1. Retention Time. Part 2. Heat and Mass Transfer, A/C/iT/. 32 263-275 (1986). 

Deploy, J.A. 1972. Analog computer simulation of paper drying A workable model, Pulp Paper Mag. Can., 75(5) T129-T136. 

Marinos-Kouris D., Mroulis Z.B., Kiranoudis C.T., 1996, Computer simulation of industrial dryers. Drying Technology, 14,971-1010. 

Rybicki A., Drying Processes Control of Materials Susceptible to Shrinkage Damage. Computer Simulations, Poznan University of Technology, Poznan, Poland, Transaction No. 482, 2012 (in Polish). 

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