Author: admin
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Summary
Years from now you may have some difficulty recalling the details presented in this text. On the other hand, the two basic premises outlined in this introductory section are so fundamental to technically educated people that you really should commit them to long-term memory as soon as possible. Formally, we may state our two basic…
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Real Fluids and Tabulated Properties
The thermodynamic behavior of real fluids differs from the behavior of ideal gases in most cases. Real fluids condense, evaporate, freeze, and melt. Characterization of the volume changes and energy changes of these processes is an important skill for the chemical engineer. Many real fluids do behave as if they are ideal gases at typical process conditions. P-V behavior…
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Basic Concepts
The System A system is that portion of the universe which we have chosen to study. A closed system is one in which no mass crosses the system boundaries. An open system is one in which mass crosses the system boundaries. The system may gain or lose mass or simply have some mass pass through it. An isolated system is one devoid of…
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The Molecular Nature of Entropy
To be fair to both of the central concepts of thermodynamics, we must mention entropy at this point, in parallel with the mention of energy. Unfortunately, there is no simple analogy that can be drawn for entropy like that for potential energy using the gravitational forces between the Earth and moon. The study of entropy…
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The Molecular Nature of Energy, Temperature, and Pressure
Energy is a term that applies to many aspects of a system. Its formal definition is in terms of the capability to perform work. We will not quantify the potential for work until the next chapter, but you should have some concept of work from your course in introductory physics. Energy may take the form…
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Introduction
These considerations should give you some idea of the potential range of applications possible within the general study of thermodynamics. This text will try to find a happy medium. One general unifying principle about the perspective offered by thermodynamics is that there are certain properties that are invariant with respect to time. For example, the…
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Basic Computational Problems
Determination of intrinsic kinetics forms an essential and important component of chemical engineering kinetics. Typically, such determinations are carried out by bench-scale batch experiments wherein the concentrations of species are monitored as a function of time and the concentration-time data are subjected to analysis. Example 9.2.1 illustrates such analysis conducted for the determination of rate expression. EXAMPLE…
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Other Considerations
The reactor analysis and design acquires another level of complexity when the reactor is operated under nonisothermal conditions; that is, the temperature of the reactor varies with time or position in the reactor, mostly due to the substantial heat effects associated with most reactions. As the temperature varies, the rate constant also changes according to…
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Conversion
The discussion in section 9.1.3 assumes that the rate expression is dependent only on the concentration of one reactant, reactant A. However, in general, the rate depends on the concentrations of several other species as well. The component balance in equation 9.1 (and its simplifications discussed earlier) can be written for each species involved in the reaction, yielding as…
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Reactor Design
A typical reactor design problem for batch reactors involves determination of the batch time needed for producing the specified quantity of the product. This batch time is obtained by separating the variables and integrating equation 9.4 as follows: Here, Ni0 are the initial moles of i. Many of the batch reactors operate under constant volume conditions; that is, the volume…