Design for Process Modeling and Behavioral Models

To enable coherent storage and information exchange inside the domain [146] and to collaboration partners, an adequate data model for material properties and behavior was necessary. Therefore, a concrete refinement and extension of the CLiP data model (see Subsect. 2.2.3) towards an implementation model has been done for the support of design processes in thermoplastic polymer processing. 

Mathematical models with different levels of structure are useful for the design of reactors, to carry out simulation studies, for process optimization and for increasing our understanding of the mechanistic, biological behavior of biochemical systems. 

In principle, ideal decouphng eliminates control loop interactions and allows the closed-loop system to behave as a set of independent control loops. But in practice, this ideal behavior is not attained for a variety of reasons, including imperfect process models and the presence of saturation constraints on controller outputs and manipulated variables. Furthermore, the ideal decoupler design equations in (8-52) and (8-53) may not be physically realizable andthus would have to be approximated. 

In many process design applications like polymerization and plasticization, specific knowledge of the thermodynamics of polymer systems can be very useful. For example, non-ideal solution behavior strongly governs the diffusion phenomena observed for polymer melts and concentrated solutions. Hence, accurate modeling of... 

The non-random two-liquid segment activity coefficient model is a recent development of Chen and Song at Aspen Technology, Inc., [1], It is derived from the polymer NRTL model of Chen [26], which in turn is developed from the original NRTL model of Renon and Prausznitz [27]. The NRTL-SAC model is proposed in support of pharmaceutical and fine chemicals process and product design, for the qualitative tasks of solvent selection and the first approximation of phase equilibrium behavior in vapour liquid and liquid systems, where dissolved or solid phase pharmaceutical solutes are present. The application of NRTL-SAC is demonstrated here with a case study on the active pharmaceutical intermediate Cimetidine, and the design of a suitable crystallization process. 

An accurate representation of the phase equilibrium behavior is required to design or simulate any separation process. Equilibrium data for salt-free systems are usually correlated by one of a number of possible equations, such as those of Wilson, Van Laar, Margules, Redlich-Kister, etc. These correlations can then be used in the appropriate process model. It has become common to utilize parameters from such correlations to obtain insight into the fundamentals underlying the behavior of solutions and to predict the behavior of other solutions. This has been particularly true of the Wilson equation, which is shown below for a binary system. 

Models are either dynamic or steady-state. Steady-state models are most often used to study continuous processes, particularly at the design stage. Dynamic models, which capture time-dependent behavior, are used for batch process design and for control system design. Another classification of models is in terms of lumped parameter or distributed parameter systems. A lumped parameter system... 

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