Full Description
A chemical engineer is generally concerned with the industrial implementation of processes in which chemical or microbiological conversion of material takes place in conjunction with the transfer of mass, heat, and momentum. The characteristics of these processes depend on their scale. They include heterogeneous chemical reactions and unit operations. Understandably, chemical engineers have always wanted to find ways of simulating these processes to gain insights assising them while designing new industrial plants or trying to optimize existing plants. Irrespective of whether the model involved represents a "scale-up" or a"scale-down," certain important questions always apply: How small can the model be? Is one model sufficient or should tests be carried out in models of different sizes? When must or when can physical properties differ? When must the measurements be carried out on the model with the original system of materials? Which rules govern the adaptation of the process parameters in the model measurements to those of the full-scale plant? Is it possible to achieve complete similarity between the processes in the model and those in its full-scale counterpart? If not: how should one proceed? These questions touch on the fundamentals of the theory of models, which are based on dimensional analysis. Although they have been used in the field of fluid dynamics and heat transfer for more than a century - cars, aircrafts, vessels and heat exchangers were scaled up according to these principles - these methods have gained only a modest acceptance in chemical engineering. This book attempts to fill this gap. It is aimed at students and practicing chemical engineers. Itconsists of two parts. The first part presents the principles of dimensional analysis and of scale-up, based on it, in an easily comprehensible and transparent manner. These principles are illustrated by 23 examples concerning well-known operations from the field of chemical engineering. The second part of the book presents selected examples of treatment of processes in the field of mechanical (11 samples), thermical (6 examples) and chemical (5 examples) process engineering by the dimensional analysis. The last chapter shows that this method can also be favourably applied to the motion processes in the living world(5 examples), leading to a better understanding of them.
Contents
Dimensional analysis: fundamental principles; what is a dimension?; what is a physical quantity?; basic and derived quantities, dimensional constants; dimensional systems; dimensional homogeneity of a physical content; the pi theorem. The determination of a pi set by matrix remodelling scale invariance of a pi-space. The fundamentals of scale-up important tips for the construction of the relevance list of a problem: treatment of universal physical constants; introduction of intermediate quantities. Important aspects concerning scale-up: scale-up at the unavailability of a model; material system scale-up under conditions of partial similarity. Preliminary summary of the essentials of scale-up: advantages of dimensional analysis; applicability of dimensional analysis; experimental techniques for scale-up. Treatment of variable physical properties by dimensional analysis: dimensionless representation of the material function; reference-invariant representation of the material function; pi-space for variable physical properties; material function for the non-Newtonian fluids pi-space for non-Newtonian fluids. Reduction of the pi-space - typical problems and mistakes in carrying out the dimensional analysis optimization of the process conditions by combining of process characteristics selected examples: selected examples of the use of dimensional analysis in the mechanical process engineering; selected examples of the use of dimensional analysis in the thermal process engineering; selected examples of the use of dimensional analysis in the chemical process engineering; selected examples of the use of dimensional analysis in the living world.
