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Efficiency Optimized Cooling Fans |
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• Up to 30% Lower Power Requirement |
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| Efficiency Optimized Cooling Fans | |
| Development of efficiency optimized cooling fans focuses on minimizing losses inherent in motor and impeller design, but the work almost always begins with application-specific goals. Beneficial results of efficiency improvement efforts are available over a wide slice of a fan's performance curve. They peak near an operating point - air flow at pressure - set by requirements of an equipment production program that inspired the research. The redesign may have ancillary objectives (noise reduction, vibration dampening, etc.), but characteristics outside the project's range of interest are allowed to float to other levels as efficiency tradeoffs. While brushless dc motors with efficiencies greater than 70 percent are not uncommon, axial fan impellers that are more than 50 percent efficient are rare. Overall, fan efficiency is the product of motor and impeller figures; that is: ηfan = ηmotor × ηimpeller. <More> |
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| Efficiency Optimized Cooling Fans | |
| Among interrelated design elements that warrant close scrutiny and experimentation in optimizing brushless dc motors are: — Motor Diameter — Core Material and Lamination (reduce iron losses) — Magnet Material, Size, Degree of Magnetization and Air Gap — Motor Geometry - Number of Slots & Poles (cut copper losses) 
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| Efficiency Optimized Cooling Fans | |
| In general, impeller efficiency increases as the diameter of a fan's hub and the number of its impeller blades decrease. The relationships are complex, since these factors are the primary determinants of the shape, angle and pitch of the airfoils that translate rotational movement into laminar flow. Reducing the number of impeller blades tends to diminish significant losses caused by the generation of vortices at the trailing edges, but it also tends to lower the air output velocity and increase the rotational movement of air, which is counterproductive and often necessitates higher fan speed to meet air flow requirements. Well-designed stationary impellers of vane axials can recover a third or more of the rotational loss associated with blade-count reduction, so that type of housing takes good advantage of the efficency boost. Dual in-line counter-rotating fans do an even better job of it. |
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