Skip to main content Accessibility help
×
  1. Home
  2. Browse subjects
  3. Engineering
  4. Chemical engineering
  5. Content listing

Refine search

Refine search

Access:
Content type:
Publication date:
Apply   From and To filters
Subject: Show more
Journals Show more
Publishers: Show more
Societies Show more
Series: Show more
Collections: Show more

Actions for selected content:

Select all | Deselect all
  • View selected items
  • Export citations
  • Download PDF (zip)
  • Save to Kindle
  • Save to Dropbox
  • Save to Google Drive

Save Search

You can save your searches here and later view and run them again in "My saved searches".

Please provide a title, maximum of 40 characters.
Cancel
×

2477 results in Chemical engineering

Page 54 of 124

  • 8 - Fugacity and vapor–liquid equilibrium

  • Juan J. de Pablo, University of Chicago, Jay D. Schieber, Illinois Institute of Technology
  • Book:
    Molecular Engineering Thermodynamics
    Published online:
    28 May 2018
    Print publication:
    10 July 2014, pp 246-281

  • Summary

    In Chapter 4 we saw how simple stability criteria derived from the postulates have important consequences for the calculation of vapor–liquid equilibria. More specifically, we discussed how the spinodal curve of a pure fluid defines the boundary between locally stable and unstable states, and we also saw how global stability leads to guidelines for the calculation of binodal, or coexistence, curves.

    As the number of components of a mixture increases, the stability criteria become increasingly complex and more difficult to apply, although the principles are the same. Calculations of phase equilibria for multicomponent mixtures therefore become more elaborate. These calculations are commonplace in applications, and it is therefore important to have an efficient machinery to address this problem. This chapter presents that machinery.

    Previous chapters dealt mostly with pure-component systems. For these we first introduced the idea of fundamental relations for U or for S (Chapter 2), and then, through Legendre transforms, we introduced fundamental relations in the generalized potentials (Chapter 3). In Chapter 4 we showed how these fundamental relations for a one-component system can be derived from two equations of state, typically a mechanical equation of state, and a thermal equation of state. We also showed in Chapter 6 how to derive fundamental relations from simple molecular models.

    However, in Chapter 4 we also showed how many things could be accomplished through the mechanical equation of state alone, such as calculations of vapor–liquid equilibrium and residual properties. For multicomponent vapor–liquid equilibrium, we will find in this chapter that mechanical equations of state are sufficient when we use a quantity called fugacity in place of the chemical potential.

  • Appendix D - Physical properties and references

  • Juan J. de Pablo, University of Chicago, Jay D. Schieber, Illinois Institute of Technology
  • Book:
    Molecular Engineering Thermodynamics
    Published online:
    28 May 2018
    Print publication:
    10 July 2014, pp 461-469

  • Summary

    WEBSITES WITH DATA AND PROGRAMS

    There are many sources available for finding physical properties, such as critical properties, heat capacities, molecular weights, etc. Besides texts, many computer packages may be accessed for the data. Below is a list of URLs that may be used to find data for many species and computer programs on the web. Most of these are free, but they may contain links to services requiring fees. Since we have no control over their content, we cannot be responsible for the accuracy or usefulness of the information supplied. URLs are not particularly stable, but they should be obtainable from a search engine, such as Google.

  • • The National Institute for Standards and Technology (NIST) keeps a tremendous amount of data online, and contains links to other sites. They also sell catalogs and computer software (webbook.nist.gov/chemistry).

  • • Data on many thermodynamic, transport, and physical properties are stored by the American Institute of Chemical Engineers at the Design Institute for Physical Property Data. A large database has free access for students (www.aiche.org/dippr).

  • • Free software, and data, such as molecular weights, critical pressures and critical temperatures, may be found for gases at Flexware (http://www.flexwareinc.com/).

  • • Professor G. R. Mansoori of the University of Illinois-Chicago maintains a website with links to many other web pages that contain data, or computer programs for thermodynamic calculation: (http://www.uic.edu/mansoori/Thermodynamic.Data.and.Property_html).

  • • The University of Texas has a Javascript program called “ThermoDex” that searches their bookshelves for thermodynamic data. The program returns only the reference for the book, however: (www.lib.utexas.edu/thermodex).

  • 3 - Generalized thermodynamic potentials

  • Juan J. de Pablo, University of Chicago, Jay D. Schieber, Illinois Institute of Technology
  • Book:
    Molecular Engineering Thermodynamics
    Published online:
    28 May 2018
    Print publication:
    10 July 2014, pp 52-111

  • Summary

    From the postulates in Chapter 2, we have already seen that from U(S, V, N1, …, Nm) or S(U, V, N1, …, Nm) we can derive all of the thermodynamic information about a system. For example, we can find mechanical or thermal equations of state. However, we also know that it is sometimes convenient to use other independent variables besides entropy and volume. For example, when we perform an experiment at room temperature open to the atmosphere, we are manipulating temperature and pressure, not entropy and volume. In this case, the more natural independent variables are T and P. Then, the following question arises: Is there a function of (T, P, N1, …, Nm) that contains complete thermodynamic information? In other words, is there some function, say G(T, P, N1, …, Nm), from which we could derive all the equations of state? It turns out that such functions do exist, and that they are very useful for solving practical problems.

    In the first section we show how to derive such a function for any complete set of independent variables using something called Legendre transforms. In this book we introduce three widely used potentials: the enthalpy H (S, P, N1, …, Nm), the Helmholtz potential F (T, V, N1, …, Nm), and the Gibbs free energy G (T, P, N1, …, Nm). These functions which contain complete thermodynamic information using independent variables besides S, V, and N1, …, Nm are called generalized thermodynamic potentials.

  • Preface

  • Juan J. de Pablo, University of Chicago, Jay D. Schieber, Illinois Institute of Technology
  • Book:
    Molecular Engineering Thermodynamics
    Published online:
    28 May 2018
    Print publication:
    10 July 2014, pp xv-xvii

  • Summary

    Students of engineering and the physical sciences are often introduced to thermodynamics in a way that has evolved little over the last several decades.

    This book is an outgrowth of the sense that thermodynamics courses should reflect changes in the problems that engineers and scientists encounter in practice. Important industrial sectors, including the oil, chemical, semiconductor, and pharmaceutical, continue to recruit large numbers of scientists and engineers, but new demands require them to be more versatile, and able to apply fundamental thermodynamic concepts in a wider range of situations. At the same time, start-ups in emerging fields must be nimble and rely on a work force that is equally comfortable applying thermodynamic principles to rationalize observations in biology or advanced materials design. Traditional boundaries between science and engineering are becoming blurred, and versatility in engineering is necessarily built on a broader understanding of far-reaching scientific principles. Engineering students must place greater emphasis on broadly applicable scientific concepts and learn how to use these in different contexts, and students in the sciences must gain a better appreciation for how such concepts are applied in engineering practice.

    One clear and common trend in most engineering and scientific disciplines is that of control over smaller length scales. Experimental methods are able to probe and manipulate the behavior of individual molecules, and large-scale processes can be used to mass produce ultra-small electronic devices. We have entered the age of “molecular engineering,” and it is important to emphasize molecular-level concepts in thermodynamics texts.

  • 7 - Molecular interactions

  • Juan J. de Pablo, University of Chicago, Jay D. Schieber, Illinois Institute of Technology
  • Book:
    Molecular Engineering Thermodynamics
    Published online:
    28 May 2018
    Print publication:
    10 July 2014, pp 211-245

  • Summary

    Previous chapters established many relations between various thermodynamic properties of a fluid. We have seen, for example, that the heat capacity of a fluid is always positive. We have also shown that the thermal, mechanical, and chemical equations of state must be mutually consistent (i.e. they must satisfy the Gibbs–Duhem equation). In the previous chapter, we showed how statistical mechanics can be used to derive fundamental thermodynamic relations from simple models of molecular interactions. In this chapter we discuss in greater detail important molecular interactions and their relative magnitudes. Specific mathematical expressions taken from physical chemistry are used to estimate when interactions are important and how they might influence thermodynamic quantities. Molecular interactions ultimately determine the behavior of materials and fluids. Hence they have received considerable attention and entire texts have been devoted to their study. Interested readers are referred to [68, 80, 99] for a more complete and thorough discussion.

    The equations of state and the transport properties of gases, liquids, and solids are intimately related to the forces between the molecules. The methods of statistical mechanics provide a connection between these forces and measurable thermodynamic properties. An introduction to statistical mechanics was presented in the previous chapter. Here we merely discuss the nature and the origin of intermolecular forces. In the following chapter we will illustrate how everything comes together to generate thermodynamic property predictions from intermolecular interactions. Finally, we note that calculation of intermolecular forces requires knowledge of several fundamental properties of molecules.

  • 10 - Reaction equilibrium

  • Juan J. de Pablo, University of Chicago, Jay D. Schieber, Illinois Institute of Technology
  • Book:
    Molecular Engineering Thermodynamics
    Published online:
    28 May 2018
    Print publication:
    10 July 2014, pp 328-364

  • Summary

    Reactions are an essential component of chemical engineering, and reaction engineering itself is a very broad discipline [43, 107]. However, before we study the time evolution of chemical reactions, it is important to know the final equilibrium state that a system can reach. The equilibrium state of a chemical reaction is determined by thermodynamic principles.

    In this chapter we examine the thermodynamic principles that govern chemical reactions, and find methods for calculating the final composition of a mixture that results from chemical reactions. The methods consist of two general steps: determination of the equilibrium constant(s) from thermodynamic properties of the constituent chemical compounds; and determination of the chemical composition of the equilibrium mixture from the initial composition and the equilibrium constant(s). In general, finding this composition requires the use of models with good estimates for the activities (or fugacities) of the constituent species, as shown in the previous two chapters. The equilibrium constant depends only on the temperature and the species present, not on the composition.

    We also consider how thermodynamic driving forces can influence reaction rates. However, few details are given in this book, since that is a topic best left for other courses and textbooks. Denaturation of DNA strands is discussed in Section 10.9, where denaturation is applied to polymerase chain reactions (PCR). PCR is a technique that can be used to amplify small amounts of genetic material. Finally, in the last section, Section 10.10, connections are made to statistical mechanics.

  • 6 - Statistical mechanics

  • Juan J. de Pablo, University of Chicago, Jay D. Schieber, Illinois Institute of Technology
  • Book:
    Molecular Engineering Thermodynamics
    Published online:
    28 May 2018
    Print publication:
    10 July 2014, pp 181-210

  • Summary

    In this chapter, we make the connection between molecules and thermodynamics. Until this chapter, we have dealt only with macroscopic quantities, and the influence of molecular details has been discussed only qualitatively. Here, we make quantitative connections between molecules and much of the thermodynamics we have already seen. For example, we derive the fundamental relations for ideal gases (simple and general), molecular adsorption on solid surfaces, and the elasticity of polymer chains. The procedure is general, and may be used to derive fundamental relations for more complex systems, to relate macroscopic experimental results to molecular interactions, or to exploit computer simulations. Since statistical mechanics deals with more detailed information than does classical thermodynamics, we can also find how real systems fluctuate in time when at equilibrium. We will see that these fluctuations are important for all systems, and can even dominate the behavior of fluids near a critical point (or spinodal curve) or that of small systems.

    This chapter is not essential for understanding most of the rest of the book. However, the remaining chapters will also have a few sections dealing with the statistical mechanics of mixtures and polymers, and the material in this chapter is essential for understanding those topics. Statistical mechanics is both beautiful and powerful, but often difficult to grasp the first time you see it. However, we believe that statistical mechanics, like thermodynamics, rewards the student who visits it repeatedly.

  • 11 - Thermodynamics of polymers

  • Juan J. de Pablo, University of Chicago, Jay D. Schieber, Illinois Institute of Technology
  • Book:
    Molecular Engineering Thermodynamics
    Published online:
    28 May 2018
    Print publication:
    10 July 2014, pp 365-392

  • Summary

    The word polymer comes from the Greek polymeres, meaning many units. It is used to designate molecules with large molecular weights. There is no exact cutoff to determine when a large molecule is actually polymeric, but chained molecules of molecular weight greater than a few thousand are typically considered to be polymers.

    Scientists and engineers are concerned both with naturally occurring and with synthetic polymers. Naturally occurring polymers are important in biotechnological and biomedical fields, for example as DNA, RNA, microtubules, or actin filament, and in other fields, such as in the form of cellulosics in high-strength fibers.

    Synthetic polymers play important roles in advanced materials such as plastics, liquid crystals, and fiber-reinforced composites. The manufacture of these materials, as well as numerous applications, can often require that the polymer be dissolved in solvents, for example in spin-coating processes. Alternatively, material scientists often wish to combine the desirable properties of two different polymers in a plastic alloy by blending different mixtures of the two.

    In this chapter, we consider the phase behavior of polymer solutions and the miscibility of polymer blends. The starting point for describing these properties is the Flory–Huggins equation for the Gibbs free energy of mixing. In Section 11.1 we compare the experimental data for the solubility of various polymer–solvent mixtures with the Flory–Huggins equation of state. We see that the theory is insufficient to describe all systems. Hence, in Section 11.2 we also consider generalizations to the Flory–Huggins approach.

Mathematical Modeling in Chemical Engineering
  • Anders Rasmuson, Bengt Andersson, Louise Olsson, Ronnie Andersson
  • Published online:
    05 June 2014
    Print publication:
    20 March 2014
  • A solid introduction to mathematical modeling for a range of chemical engineering applications, covering model formulation, simplification and validation. It explains how to describe a physical/chemical reality in mathematical language and how to select the type and degree of sophistication for a model. Model reduction and approximation methods are presented, including dimensional analysis, time constant analysis and asymptotic methods. An overview of solution methods for typical classes of models is given. As final steps in model building, parameter estimation and model validation and assessment are discussed. The reader is given hands-on experience of formulating new models, reducing the models and validating the models. The authors assume the knowledge of basic chemical engineering, in particular transport phenomena, as well as basic mathematics, statistics and programming. The accompanying problems, tutorials, and projects include model formulation at different levels, analysis, parameter estimation and numerical solution.

Heat Transfer Physics
  • 2nd edition
  • Massoud Kaviany
  • Published online:
    05 June 2014
    Print publication:
    10 February 2014
  • This graduate textbook describes atomic-level kinetics (mechanisms and rates) of thermal energy storage, transport (conduction, convection, and radiation), and transformation (various energy conversions) by principal energy carriers. The approach combines the fundamentals of molecular orbitals-potentials, statistical thermodynamics, computational molecular dynamics, quantum energy states, transport theories, solid-state and fluid-state physics, and quantum optics. The textbook presents a unified theory, over fine-structure/molecular-dynamics/Boltzmann/macroscopic length and time scales, of heat transfer kinetics in terms of transition rates and relaxation times, and its modern applications, including nano- and microscale size effects. Numerous examples, illustrations, and homework problems with answers that enhance learning are included. This new edition includes applications in energy conversion (including chemical bond, nuclear, and solar), expanded examples of size effects, inclusion of junction quantum transport, and discussion of graphene and its phonon and electronic conductances. New appendix coverage of Phonon Contributions Seebeck Coefficient and Monte Carlo Methods are also included.

Adhesive Particle Flow
  • A Discrete-Element Approach
  • Jeffery S. Marshall, Shuiqing Li
  • Published online:
    05 June 2014
    Print publication:
    31 March 2014
  • Offering a comprehensive treatment of adhesive particle flows, this book adopts a particle-level approach oriented toward directly simulating the various fluid, electric field, collision, and adhesion forces and torques acting on the particles, within the framework of a discrete-element model. It is ideal for professionals and graduate students working in engineering and atmospheric and condensed matter physics, materials science, environmental science, and other disciplines where particulate flows have a significant role. The presentation is applicable to a wide range of flow fields, including aerosols, colloids, fluidized beds, and granular flows. It describes both physical models of the various forces and torques on the particles as well as practical aspects necessary for efficient implementation of these models in a computational framework.

Page 54 of 124