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Fan
Size and Energy Efficiency
Richard
Aynsley
School of Engineering Technology & Management
Southern Polytechnic State University, Marietta, GA, USA
Abstract
The use of ceiling mounted circulating fans to provide air movement for
cooling in industrial premises and animal houses is particularly essential
in warm, humid climates. Methods to substantially improve the efficiency
of this approach are demonstrated in this paper.
Fan laws are identified as one source of strategies for increasing
energy-efficiency of fans. Industrial ceiling fans are used to demonstrate
that using larger, slower, fans will not only improve energy efficiency
but also reduce fan noise. By using large diameter fans (7.3m diameter) in
place of conventional fans, energy savings of over 40% are demonstrated.
Field studies of air flow characteristics from ceiling fans are shown to
provide further opportunities to increase air flow efficiency in
industrial buildings. Utilising lower friction losses associated with the Coanda
effect in air flow adjacent to the floor is shown to increase air flow
toward the outer limits of the radial outflow. Lower fan mounting heights
are also shown to provide increased air flow toward the outer limits of
the radial outflow. For situations where the floor plane has numerous
obstructions to air flow, CFD software is suggested as a means to simulate
air flow before installation of fans. Where possible, validation of CFD
software output against physical measurements is advised.
Key Words: circulating
fans, industrial buildings, cooling, fan efficiency.
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