Engineering analysis of processing

Unfortunately, the Reynolds-Nusselt dimensional analysis studies are not directly applicable to polymer melt and rubber processing for two important reasons. First, they are based on Newtonian fluid behavior, and second, they do not include viscous dissipation heating. 

We begin with Cauchy s law of motion, Eq. (10), and a general constitutive equation such as Eq. (47), which yields 

A characteristic velocity U and length L are introduced into this equation and the entire expression is put in dimensionless form. These dimensionless groups are 

Lii is a characteristic length in the direction of flow. The Deborah number is equivalent to a Weissenberg number with the characteristic length in the direction of flow. Our dimensionless groups thus reduce to 

The results of the preceding paragraph have some important implications. First, the characteristic velocity and length arise in only one group, and this 

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Figure 2.16. Strategy for engineering analysis of process kinetics according to a systematic empirical approach. Bioreactors of different scales are used to obtain process engineering data at different stages (1-3) of development (From Moser, 1978a.)...

One of the common problems associated with underwater pelletizers is the tendency of the die holes to freeze off. This results in nonuniform polymer melt flow, increased pressure drop, and irregular extrudate shape. A detailed engineering analysis of pelletizers is performed which accounts for the complex interaction between the fluid mechanics and heat transfer processes in a single die hole. The pelletizer model is solved numerically to obtain velocity, temperature, and pressure profiles. Effect of operating conditions, and polymer rheology on die performance is evaluated and discussed. 

The work of Crank [38] provides a review of the mathematical analysis of well defined component transport in homogeneous systems. These mathematical models and measured concentration profile data may be used to estimate diffu-sivities in homogenized samples. The use of MRI measurements in this way will generate diffusivities applicable to models of large-scale transport processes and will thereby be of value in engineering analysis of these processes and equipment. 

Systematic engineering analysis of chemical processes led to the definition of a series of unit operations, such as distillation, absorption, and filtration, which are common to different chemical processes (e.g., see W. L. McCabe and J. C. Smith, Unit Operations in Chemical Engineering, 2nd ed., McGraw-Hill, New York, 1967). 

In most process control courses for chemical engineers, the first part of the course normally deals with the development of dynamic process models from first principles (mass and energy balances), since these are used in the analysis of process dynamics and often also for controller tuning. In this chapter, however, the focus will be on process control and modelling will not be considered. Neither will the chapter consider... 

The primary anti-wear variants for today s barrels are usually a solid barrel or a barrel with a replaceable insert. The type selected depends on a thorough analysis of process engineering and production engineering, as well as economical aspects. 

Numerous industrial applications of applied thermodynamics have been reported in the literature for engineering analysis of wide varieties of chemical systems and processes. For example, Chen and Mathias reported examples of physical property modeling for the high-density polyethylene process and for sulfuric acid plants. Here, we present two recent examples that are illustrative of numerous applications of applied thermodynamics models in the industry for various process and product development studies. 

While new chemical product development has historically been the domain of chemists, the use of chemical products by consmners invariably involves some transformation of the product due to applied stresses, temperature gradients, physicochemical hydrodynamics, mass transfer, etc., making product use a process in the chemical engineering sense. [2,4] Thus the analysis of product behavior ultimately requires the same fundamentals as the analysis of process behavior, and is well suited to study by chemical engineers. 

Engineering analysis of extractions has two aspects. Part 1 is the determination of the system equilibrium conditions or the thermodynamic driving force for the extraction. Part 2 is the governing equations for the process. 

These first two steps require the talents of process engineers. Knowledge of process design, reaction engineering, and economics is invaluable for proper diagnosis and analysis. ... 

Table 17.1 shows the aspects of process safety for which actions are required by OSHA in Title 29 of the Code of Federal Regulations, Part 1910, Section 119 (29 CFR 1910.119) [1] and by the EPA in Title 40 of the Code of Federal Regulations, Part 68 (40 CFR 68) [2]. This Chemical Process Safety section concentrates on the engineering aspects of Process Safety Information —on the consequences of failure of engineering and administrative controls and the qualitative evaluation of a range of the possible safety and health effects of failure of controls requirements of the OSHA and EPA Process Hazards Analysis and the Off-Site Hazard Assessment. ... 

In their engineering analysis of the HNO3-NO process, Garrett and Schacter [G2] considered a plant to produce 30.2 g-mol N/day while simultaneously producing 239,670 g-mol H2S04/day. They recommended use of substantially the same conditions employed by Taylor and Spindel and estimated that could be produced at a cost of 4/g. This relatively low cost is due to the credit for converting SO2 to H2SO4. 

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