Kinetics drying modeling

J Wolff, E., Gibert, H. Rudolf, F Vacuum freeze-drying kinetics and modeling of a liquid in a vial. Chem. Eng. Process., 25 (3), p. 153-158, 1989... 

Numerical simulation results of batch and continuous drying models for slices of peppers in packed beds were presented in this work. The reported models were based on differential mass and energy balances in the dryer along with kinetic equations describing transport phenomena in individual particles and product quality deterioration. The shrinkage problem was... 

Sanchez J. 1994. Kinetics and Models of Silicon Alkoxide Polymerization. [AVM] Cairncross R.A. 1994. Solidification Phenomena During Drying of Sol-to-Gel Coatings. [LEE, LES]... 

M. Mezhericher, A. Levy, 1. Borde, Spray drying model-hng based on advanced droplet drying kinetics. Chemical Engineering and Processing, 49 (2010) 1205-1213. 

Here we will first compare the implication of the DRIS formalism with the predictions of the kinetic Ising model of Glauber [39] and discuss the results in relation to the theory of Shore and Zwanzig [40]. It should be noted that the model of Glauber is of fundamental importance, inasmuch as this is the first work in which the Markov character of a chain is rigorously considered and an analytical expression is provided for the time decay of correlation functions associated with a linear array of pairwise interdependent units. In the second part of this section, some empirical expressions previously proposed for describing OACFs, will be considered. 

The elements of the transition rate matrix A in the DRIS model are estimated from the multidimensional energy surface associated with the interdependent rotation of neighboring bonds u g Kramers rate theory, as described above. Accordingly, the probability of occurrence of a given isomeric state for a bond depends on the state of its first neighbors aloi the chain. Likewise, in the kinetic Ising model the transition rate Wi(Oi) of the i-th spin is assumed to be coupled to the state of its first iKighbors by the relation... 

Calculations of C,( 0 for polyethylene have been performed according to the DRIS model [7] and the results have been compared with BD simulations performed by Weber and Helfand [98]. Conformational autocorrelation functions for the trans and gauche states based on the kinetic Scheme 2 of the DRIS... 

As depicted in Fig. 2.24, there is a very good agreement between experimental and simulated quality kinetics. In addition, it should be noted that the simulation of the quality kinetic is heavily reliant on the simulation of the rice temperature and moisture gradient, as computed by the underlying drying model. 

On the basis of our kinetic results, our heats of oxidation mentioned above, independent heats of total combustion (Yan, H-k. Hepler, L.G. to be published), our chemical analyses, and the results of earlier investigations by others (11-15), we have developed a chemical model or picture of the dry oxidation process as follows. 

Two observationally constrained box-models, based on the Master Chemical Mechanism and with different levels of chemical complexity, have been used to study the HOx radical chemistry during the SOAPEX-2 campaign, which took place during the austral summer of 1999 (January-February) at the Cape Grim Baseline Air Pollution Station in northwestern Tasmania, Australia. The box-models were constrained to the measured values of long lived species and photolysis rates and physical parameters (NO, NO2, O3, HCHO, j(01D), j(N02), H2O and temperature). In addition the detailed model was constrained to the measured concentration of CO, CH4 and 17 NMHCs, while the simple model was additionally constrained only to CO and CH4. The models were updated to the latest available kinetic data and completed with a simple description of the heterogeneous uptake and dry deposition processes. 

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