Theory and Design Principles

Our discussion up to now has concerned the cooling of hot process waters exclusively. However, we insisted back in Chapter 1 that a cooling tower is nothing more than a device that transfers heat from one mass to another. Therefore, gas coolers are governed by the same theory of operation and design principles as are water cooling towers. 

The theory and design of all particle size measurement devices are based on the assumption that particles are spherical. Most materials submitted for size analysis are not spherical. When these materials are analyzed by instruments employing different physical principles, the results are different. Figure 8 illustrates this point by comparing the cumulative (percent passing) distribution of three identical samples analyzed on three different instruments, each employing a different measurement technique. The absolute values of the distributions are different, but their shapes are quite similar. Because these results usually exhibit differences which are consistent, a correlation can be determined between one or more parameters of the distribution. 

The development process for large, expensive and complicated equipment of commercial importance is generally divided into several stages in order to reduce the investment risk. For example theory and physical principles are validated first, and then, after engineering analysis, a prototype component is designed, built and tested. Finally products are acceptance tested and are then ready for commercialization. 

Electrical engineers have made and continue to make significant contributions to the field of communications. They use their knowledge of wave propagation, electromagnetic theory, and electronic principles to design radio, telephone, television, and satellite communication systems. Approximately 7 percent of electrical engineers work in the communications specialty. 

Section A The following references are recommended for more in-depth readings on absorption and solvent extraction theory, design principles, and practical applications. 

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