What Is a DC Axial Fan?
A DC axial fan is an axial fan that uses a DC power source to cool equipment.
The purpose of installing a DC Axial fan is to exhaust the heat generated inside the equipment to the outside or, conversely, to supply heat from the outside to the inside of the equipment. This makes it possible to control the temperature inside the equipment.
Generally, heat is generated when equipment is operated. If left unchecked, the temperature of the electronic components inside the equipment will rise, resulting in failure or damage in the worst case. In this case, a DC axial fan can be used to exhaust the heat generated in the equipment and prevent accidents from occurring.
Uses of DC Axial Fans
The main use of DC axial fans is to cool electronic components such as capacitors and ICs in notebook and desktop PCs, control panels, measuring equipment, OA equipment, communication equipment, power supplies, and medical and scientific equipment.
DC axial fans are also used to ensure long-term stable use and temperature control of automobile cooling fans, air conditioner fans, etc.
Principle of DC Axial Fans
A typical DC axial fan consists of a bladed plastic or metal cooling fan attached to a motor driven by a DC power source. Air is drawn in from the front of the fan and exhausted out the back to cool the inside of the equipment. Conversely, some fans intake air from the rear of the fan and exhaust air from the front.
Axial fans are fans that blow air in the axial direction. They are the most efficient of all turbo fans and are widely used for cooling heat-generating devices. Axial fans are characterized by the fact that the increase or decrease in airflow due to resistive objects is relatively small. When axial fans are installed in equipment, noise and power consumption of the equipment can be reduced by setting the operating point of the fan to the maximum airflow side.
Furthermore, in recent years, DC axial fans with PWM (Pulse Width Modulation) control, used in notebook and desktop PCs, have the ability to externally control the fan’s rotation speed. This allows for appropriate control of environmental temperatures.
How to Select a DC Axial Fan
When selecting a DC axial fan, first estimate the amount of heat generated in the equipment, W. The amount of heat generated can be calculated by converting the power consumption of the equipment into heat value. Then, the allowable temperature rise in the equipment, ΔT, is determined as the difference between the allowable temperature of the equipment and the maximum suction temperature of the fan.
Next, the required air volume Q to satisfy the allowable temperature rise value ΔT is calculated. The system resistance is also estimated based on the ventilation resistance in the equipment or historical data. Finally, the pressure P-airflow Q characteristic of the axial fan is used to select a fan.
If it is difficult to estimate the draft resistance, the fan is selected so that the maximum airflow is 1.3 to 2 times the required airflow. On the other hand, the use of a fan can cause dust and other particles to continue flowing into the equipment to be cooled for a long period of time, which can lead to failure or damage of electronic components.
In this case, a filter on the intake side in front of the fan can prevent dust and foreign matter from flowing into the equipment. However, ventilation resistance must be added.
Other Information on DC Axial Fans
1. DC Fan Motor
DC fan motors used in DC axial fans are fan motors that run on a DC power supply. DC motors are widely used in both industrial and general applications. They are simple in construction and can be operated by batteries. For industrial use, they are used in automobile cooling fans, air conditioner fans, etc.
The structure of a DC fan motor consists of a rotor, which consists of an iron core, wound coils, and commutator, and a stator, which consists of an iron core, wound coils or permanent magnets, and brushes, in the case of a general brush type. In a brush-type DC fan motor, the magnetic field of the rotor becomes a rotating magnetic field under the action of the commutator in the magnetic field created by the stator, generating the driving force. Rotation speed can be easily varied by changing the strength of the magnetic field of the rotor.
Brushless DC fan motors, which have become widely used in recent years, use permanent magnets in the rotor and use a magnetic field generating circuit in the stator to change the rotation speed. Their adoption is increasing due to the advantages of efficiency and the fact that brush maintenance is not required.
2. Difference Between DC Axial Fans and AC Axial Fans
The difference between DC axial fans and AC axial fans is the power source that drives the fan: DC axial fans are driven by a DC power source, while AC axial fans are driven by an AC power source.
DC axial fans can change their rotation speed depending on the motor circuit. On the other hand, AC axial fans have a constant fan speed depending on the frequency of the AC power supply.