风扇的选取（NMB EBM FAN） - 热设计论坛

Engineering Information
Most densely packaged electronic systems use a fan or blower for forced-air cooling. Smaller systems usually use axial cooling
fans where airflow is perpendicular to the fan blades. However,larger systems may require centrifugal blowers to deliver adequate
airflow in high static pressure situations.
The need for forced-air cooling should be determined at an early stage in system design. It is important that the design plans
for good airflow to heat-generating components and also allows adequate space and power for the cooling fan.
Factors to be considered in fan selection include: required airflow, AC or DC power, voltage, speed, life expectancy,
EMI/RFI, heat dissipation, auto-restart and audible noise.
The first stage in designing a forced-air cooling system is to estimate the required airflow. This depends on the heat generated
within the enclosure and the maximum temperature rise permitted.
AC input power is usually a good approximation of the power dissipated within the enclosure.
In estimating the power dissipated within a system, the possibility of future changes and additions of heat-generating
subsystems should be allowed for. Therefore, the power dissipation figure used should be a worst-case estimate for
a fully loaded system.

Understanding the Differences in Fans, Impellers and Blowers

Select either AC or Brushless DC models:
Tubeaxial Fans
  Readily available and inexpensive
  Many sizes and performances
  Good to excellent efficiency
  Axial air flow pattern
Axial & Propeller Fans
  Very high air flows
  Good efficiency
  Many sizes and performances
  Axial air flow pattern
Backward Curved Impellers
  Compact package size
  Excellent efficiency
  Quietest performance
  Many airflow options
  Even, tangential air flow