فين الكتب يا باشا لما ضغطت على الرابط طلع الاتى:
Improving Fan System Performance
Fans are widely used in industrial and commercial applications. From shop ventilation to material handling to boiler applications, fans are critical
for process support and human health. In the manufacturing sector, fans use about 78.7 billion kilowatt-hours2 of energy each year. This con-
sumption represents 15 percent of the electricity used by motors.3 Similarly, in the commercial sector, electricity needed to operate fan motors composes a large portion of the energy costs for space conditioning.
Fan selection is a complex process that starts with a basic knowledge of system operating requirements and conditions such as airflow rates, temperatures, pressures, airstream properties, and system layout. The variability of these factors and other considerations, such as cost, efficiency, operating life,maintenance, speed, material type, space constraints, drive arrangements, temperature, and range of operating conditions, complicate fan selection. However, knowledge of the important factors in the fan selection process can be helpful for the purposes of reducing energy consumption during system retrofits or expansions. Often, a fan
type is chosen for nontechnical reasons, such as price, delivery, availability, or designer or operator familiarity with a fan model. If noise levels, energy
costs, maintenance requirements, system reliability, or fan performance are worse than expected, then the issue of whether the appropriate fan type was
initially selected should be revisited.
Electric Motor Load and Efficiency