Engineering calculations, presentation

A container full of hydrocarbons can be described in a number of ways, from a simple measurement of the dimensions of the container to a detailed compositional analysis. The most appropriate method is usually determined by what you want to do with the hydrocarbons. If for example hydrocarbon products are stored in a warehouse prior to sale the dimensions of the container are very important, and the hydrocarbon quality may be completely irrelevant for the store keeper. However, a process engineer calculating yields of oil and gas from a reservoir oil sample will require a detailed breakdown of hydrocarbon composition, i.e. what components are present and in what quantities. 

Experimentally it has been shown that for air-water systems the value of Tj /Zc c, the psychrometric ratio, is approximately equal to 1. Under these conditions the wet-bulb temperatures and adiabatic-saturation temperatures are substantially equal and can be used interchangeably. The difference between adiabatic-saturation temperature and wet-bulb temperature increases with increasing humidity, but this effect is unimportant for most engineering calculations. An empirical formula for wet-bulb temperature determination of moist air at atmospheric pressure is presented by Liley [Jnt. J. of Mechanical Engineering Education, vol. 21, No. 2 (1993)]. 

There have been books on droplet-related processes. However, the present book is probably the first one that encompasses the fundamental phenomena, principles and processes of discrete droplets of both normal liquids and melts. The author has attempted to correlate many diverse mechanisms and effects in a single and common framework in an effort to provide the reader with a new perspective of the identical basic physics and the inherent relationship between normal liquid and melt droplet processes. Another distinct and unique feature of this book is the comprehensive review of the empirical correlations, analytical and numerical models and computer simulations of droplet processes. These not only provide practical and handy approaches for engineering calculations, analyses and designs, but also form a useful basis for future in-depth research. Therefore, the present book covers the fundamental aspects of engineering applications and scientific research in the area. 

The following examples are presented for individual unit operations found within a fuel cell system. Unit operations are the individual building blocks found within a complex chemical system. By analyzing example problems for the unit operation, one can learn about the underlying scientific principles and engineering calculation methods that can be applied to various systems. This approach will provide the reader with a better understanding of these fuel cell power system building blocks as well as the interactions between the unit operations. For example, the desired power output from the fuel cell unit operation will determine the fuel flow requirement of the fuel processor. 

Caution The equations presented in this chapter for polytropic head and compression work have been simplified for clarity. They cannot be used for rigorous engineering calculations.)... 

Chapter 6, which immediately follows, presents experimental methods and data for comparison with predictions in the present chapter. Such data will form the foundation for future modifications of theory in hydrate phase equilibria. However, the above thermodynamic prediction accuracies are usually satisfactory for engineering calculations, so that the state-of-the-art in hydrates is turning from thermodynamic (time-independence) to kinetics (time-dependence) phenomena,... 

For resenroir engineering calculations various properties of the crude oil and its associated gas and water must be known. It will be shown that theoretically many of these properties could be calculated by the methods presented in previous chapters, provided the composition of the system is known and complete equilibrium constant data for all of the components are available. However, since this information is seldom at hand, values of the reservoir fluid characteristics are usually experimentally determined or approximated by methods that experience has shown to be sufliciently accurate for most engineering computations. 

Ine Sonntag equation strictly only applies to water vapor with no other gases present (i.e., in a partial vacuum). The vapor pressure of a gas mixture, e.g., water vapor in air, is given by multiplying the pure liquid vapor pressure by an enhancement factor/, for which various equations are available (see British Standard BS 1339 Part 1, 2002). However, the correction is typically less than 0.5 percent, except at elevated pressures, and it is therefore usually neglected for engineering calculations. 

For process engineering calculations it is almost inevitable that experimental values of D or f), even if available in the literature, will not cover the entire range of temperature, pressure, and concentration that is of interest in any particular application. It is, therefore, important that we be able to predict these coefficients from fundamental physical and chemical data, such as molecular weights, critical properties, and so on. Estimation of gaseous diffusion coefficients at low pressures is the subject of Section 4.1.1, the correlation and prediction of binary diffusion coefficients in liquid mixtures is covered in Sections 4.1.3-4.1.5. We do not intend to provide a comprehensive review of prediction methods since such are available elsewhere (Reid et al., 1987 Ertl et al., 1974 Danner and Daubert, 1983) rather, it is our purpose to present a selection of methods that may be useful in engineering calculations. 

The practical use of chromatographic and electrophoretic separations in the biotechnology industry will be aided by correlations capable of relating bench scale results to process scale conditions. Published physical and chemical property data on chromatographic systems for engineering calculation purposes currently appears to be limited. Hence, an effort was made in this chapter to present equations which can be used with physical parameters for which values have been reported or which are readily determined on a bench scale. Since size exclusion chromatography is important in fractionation of proteins, the rationale and equations were presented for estimating ... 

DEFINITIONS. In humidification operations, especially as applied to the system air-water, a number of rather special definitions are in common use. The usual basis for engineering calculations is a unit mass of vapor-free gas, where vapor means the gaseous form of the component that is also present as liquid and gas is the component present only in gaseous form. In this discussion a basis of a unit mass of vapor-free gas is used. In the gas phase the vapor will be referred to as component A and the fixed gas as component B. Because the properties of a gas-vapor mixture vary with total pressure, the pressure must be fixed. Unless otherwise specified, a total pressure of 1 atm is assumed. Also, it is assumed that mixtures of gas and vapor follow the ideal-gas laws. 

Chen and Kuo [12] have presented approximate solutions of 0/0, and QIQ, for the plates and long cylinders. The accuracy of these solutions is acceptable for engineering calculations. 

Simprosys is based on extensive studies presented in the most authoritative drying technology journal handbooks in drying by Mujumdar (2006), Masters (1985), and Perry (1977) and many other handbooks on chemical engineering calculations and unit operations such as Chopey (2003), Reynolds et al. (2002), Walas (1990), Ibarz and Barbosa-Canovas (2002), and Kuppan (2000). 

Finally, it is worth noting that in many engineering calculations it may be sufficient to record the results of a calculation to a fewer number of significant digits than obudned following the rules esplained previously. In this book, we present the results of example problems with two or three dedmal poin . 

In connection with this discussion it might be said that a rather simple method of structuring, such as, for example, distinguishing between the quantity of protein and the quantity of nucleic acids present, can lead to a great number of otherwise inaccessible parameters (Reuss, 1977). This can make an important contribution to the understanding of intracellular events. For engineering calculations, however, the primary claim of simplicity must also be satisfied. Furthermore, within the scope of the analytical methods presently available, distinctions among models are often simply not possible (Boyle and Berthouex, 1974). 

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