Explanation of the terminology of the performance of the DC fan.Heater Fan direct sales

　　A DC fan is an auxiliary device that dissipates heat for mechanical equipment through wind, which is of great significance to the normal operation of the equipment. There are many indicators to measure the performance of a DC fan, and you may be dazzled by it for a while, not knowing its meaning. In this article, we will explain the performance terms of DC fans one by one.

　　Air volume

　　Air volume refers to the total volume of air discharged or incorporated by the DC fan per minute. If it is calculated in cubic feet, the air volume unit is CFM; if it is calculated in cubic meters, it is CMM. The air volume unit often used by DC fans is CFM (about 0.028 cubic meters per minute).

　　The air volume is the most important indicator to measure the cooling capacity of the DC fan. Obviously, the larger the air volume, the higher the heat dissipation capacity of the DC fan. This is because the heat capacity ratio of the air is constant, and a larger air volume, that is, more air per unit time, can take away more heat. Of course, in the case of the same air volume, the heat dissipation effect is related to the flow of the wind.

　　wind pressure

　　Air pressure and air volume are two relative concepts. Generally speaking, under the consideration of cost saving by manufacturers, to design a fan with a large air volume, it is necessary to sacrifice some air pressure. If the fan can drive a lot of air flow, but the wind pressure is small, the wind cannot blow to the bottom of the radiator (this is why some fans rotate at high speed and the air volume is large, but the heat dissipation effect is not good), on the contrary, High wind pressure often means that the air volume is small, and there is not enough cold air to exchange heat with the heat sink, which will also cause poor heat dissipation.

　　speed of the fan

　　Fan speed refers to the number of times the fan blades rotate per minute, and the unit is rpm. The fan speed is determined by the number of turns of the coil in the motor, the working voltage, the number of fan blades, the inclination angle, the height, the diameter and the bearing system. There is no necessary connection between speed and fan quality. The rotational speed of the fan can be measured by the internal rotational speed signal, or it can be measured externally.

　　With the change of application conditions and ambient temperature, different speed fans are sometimes required to meet the needs. Some manufacturers specially design DC fans with adjustable fan speed, which are divided into manual and automatic. The main purpose of manual is to allow users to use low speed in winter to obtain low noise, and use high speed in summer to obtain good cooling effect. The automatic thermostat radiator generally has a temperature control sensor, which can automatically control the speed of the fan according to the current working temperature. If the temperature is high, the speed will be increased, and if the temperature is low, the speed will be reduced to achieve a dynamic balance and reduce wind noise. Maintain an optimal combination with the heat dissipation effect.

　　fan noise

　　In addition to the heat dissipation effect, the working noise of the fan is also a common concern. Fan noise is the size of the noise generated by the fan when it is working. It is affected by many factors, and the unit is decibel (dB). When measuring the noise of the fan, it needs to be carried out in an anechoic chamber with a noise of less than 17dB, one meter away from the fan, and aligned with the air inlet of the fan along the direction of the fan shaft, and the A-weighted method is used for measurement. The spectral characteristics of fan noise are also very important, so it is also necessary to use a spectrum analyzer to record the noise frequency distribution of the fan. Generally, the noise of the fan should be as small as possible, and there should be no abnormal sound.

　　Fan noise is related to friction and air flow. The higher the fan speed and the larger the air volume, the louder the noise will be. In addition, the vibration of the fan itself is also a factor that cannot be ignored. Of course, the vibration of a high-quality fan will be very small, but the first two are difficult to overcome. To solve this problem, we can try to use a larger size fan. In the case of the same air volume, the working noise of the large fan at low speed should be smaller than that of the small fan at high speed. Another factor that we tend to ignore is the bearing of the fan. When the fan rotates at high speed, there is friction and collision between the shaft and the bearing, so it is also a major source of fan noise.

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