We are pleased to be able to present the Ninth Edition of
Fan Engineering, which is recognised worldwide as
THE definitive handbook on fan design and fan applications, and reflects our lengthy experience with fan design.
Fan Engineering has been written as a handbook for engineers who use fans. It is organised into four parts.
The name Howden has been associated with the fan industry since the early days of the industrial revolution. James Howden began his consulting business in 1854. His patent for a method of preheating combustion air led to the design of mechanical draft systems in 1866. During the last half of the nineteenth century the B.F. Sturtevant Company, the Buffalo Forge Company, the Fuel Economiser Company, and Davidson and Company were among those competing in the manufacture of fans. Each made valuable contributions to the art and science of fan engineering as did those which followed in the twentieth century like Ventilatoren Stork, Nordisk Ventilator Company, Voith, and Novenco Industries.
By 1970 when the Howden Group was formed the company had subsidiaries in Australia, South Africa, and North America. Beginning in 1988, Howden began a program to acquire the finest fan companies around the world. As a result, the Howden portfolio of products includes the best of the following: Airex, Airscrew, American Blower, Berry, Buffalo Forge, Canadian Blower, Carter, Davidson, Engart, Green, Howden Joy, Turbowerke, Meissen Ventilateurs, Neu Novenco Industries, Phoenix, Powermax, Safanco, Shelden, Sirrocco, Ventilatoren Stork B.F., Sturtevant, Variax, Voith-Novenco, and Wheeler. The Howden Group markets fans throughout the world. Subgroups serve Europe, The Americas, Asia Pacific, and Southern Africa.
The thermodynamic and transport properties of gases and vapors are important in fan engineering. This chapter deals with the thermodynamic properties, especially pressure, temperature, humidity, density, and enthalpy Transport properties, such as viscosity, thermal conductivity, and diffusivity, are dealt with in subsequent chapters. The gaseous materials most frequently encountered in fan engineering are air and water vapor; accordingly, most of the data are for these substances. Some formulae have been written specifically for these materials, but most are generalized to accommodate any gas.
Atmospheric air is a mixture of dry air, water vapor, and impurities. Dry air is a mechanical mixture of gases, whose principal constituents are listed in Table 1.1. (The table values may be considered representative of the composition of normal outdoor air throughout the troposphere.) The amount of water vapor in atmospheric air will depend on weather conditions. The nature and amount of impurities in the atmosphere depend on the forces at work in producing and dispersing contaminants. Industrial, urban, rural, seaside, and other areas have characteristic atmospheres due to differences in impurities.
The reference for Table 1.1 lists neon, helium, krypton, hydrogen, xenon, ozone, and radon, totaling less than 0.0025 percent by volume, as the residual part of atmospheric air. also lists methane, nitrous oxide, sulfur dioxide, nitrogen dioxide, ammonia, carbon monoxide, and iodine, totaling 0.0003 percent by volume, as constituents of normal, clean, dry atmospheric air. ASHRAE considers all these gases in the calculation of the apparent molecular weight of clean, dry atmospheric air and obtains a value of 28.9645. Rounding off and lumping the residuals with the nitrogen, as has been done in Table 1.1, yields an apparent molecular weight of 28.964.
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