Fan Formulas and Affinity Laws

In fan engineering, standard air is considered to be air with a density of 0.075 lbm/ft3 when English units are used and 1.2 kg/m3 when SI units are used. Commonly applied industry values for standard air are shown in Table 32-1. For moist air, it is common to assume a humidity of 50% and a temperature of 68°F (527.7°R) in English units and 20°C (293.2°K) in SI units.

Flow rates may be considered on a mass or volumetric basis. On a mass basis, the flow rate is the mass of the

If the fan draws directly from atmosphere:

If the fan discharges directly to atmosphere:

Fig. 32-5 Blade Design for Backward, Radial, and Forward Tips. Source: Buffalo Forge, The Howden Fan Company

Table 32-1 Commonly Applied Industry Values

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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