The selection and calculation method of the cooling fan, and how to calculate the air volume of the

I hope I can use it if I find it on the Internet.

Calculation method of fan heat dissipation and exhaust air volume.

Author:Full Fan Wanxin Motor Taiwan Blower Taiwan High Pressure Fan Full Wind Annular Fan Shanghai Hexin Electromechanical Technology **** Company Products Company Business Opportunities Company Investment Company News.

Thermal calculations. When the high-voltage inverter is working normally, the heat is mainly isolated transformer, reactor, power unit, control system, etc., among which the heat dissipation of the power device as the main circuit electronic switch, the heat dissipation design of the power unit and the heat dissipation and ventilation design of the power cabinet are the most important. For IGBT or IGCT power devices, the PN junction must not exceed 125 and the package housing is 85.

Studies have shown that if the temperature of a component fluctuates by more than 20, its failure rate will increase by 8 times.

Thermal design considerations.

1) Select components and materials with good heat resistance and thermal stability to increase their allowable working temperature;

2) Reduce the heat generated inside the device (device). To this end, micropower devices, such as low-loss IGBTs, should be selected, and the number of heat-generating components should be minimized in the circuit design, and the switching frequency of the devices should be optimized to reduce heat generation.

3) Adopt appropriate heat dissipation methods and cooling methods to reduce the ambient temperature and speed up heat dissipation.

Exhaust airflow calculation.

In the case of the worst ambient temperature, the minimum wind speed is calculated when the maximum temperature of the radiator reaches the required level. According to the wind speed, the exhaust air volume is determined according to the redundant amplification. The formula for calculating the exhaust airflow is: qf=q (cp* *t).

where: qf: the amount of air that must be supplied by the forced air cooling system.

Q: The total thermal power consumption of the equipment to be cooled, W.

cp = 1005 j (kg*) specific heat of air, j (kg*).

Air density, m2 kg.

t=10: the temperature difference between the air at the inlet and outlet.

According to the air volume and wind pressure to determine the fan model, so that the fan works at the highest point of efficiency, which increases the life of the fan and improves the ventilation efficiency of the equipment.

If measured in cubic feet, the unit is cfm; If it is calculated in cubic meters, it is CMM, and the air volume unit often used in radiator products is CFM.

In the case of the same heat sink material, the air volume is the most important indicator to measure the heat dissipation capacity of the air cooler. Obviously, the higher the air volume, the higher the heat dissipation capacity of the radiator. This is because the heat capacity of the air is certain, and the larger the air volume, that is, more air per unit time can take away more heat.

Of course, the heat dissipation effect in the case of the same air volume is related to the way the wind flows.

The air circulation per unit time is dismantled, and there are other subdivisions such as air supply volume and fresh air volume

The volume of air supply is used to indicate the capacity of ventilation equipment such as blowers, and is measured in cubic meters of seconds.

Fresh air volume refers to the total amount of fresh air in the room.

China's national standard GB T18883-2002 stipulates that the fresh air volume should not be less than 30m3 hPerson.

Airflow refers to the total volume of air discharged or classified by the air-cooled radiator fan per minute, if calculated in cubic feet, the unit is CFM; If it is calculated in cubic meters, it is CMM. The unit of air volume often used in radiator products is cfm (about cubic meter minutes). A 50x50x10mm CPU fan will typically reach 10 CFM, and a 60x60x25mm fan will typically reach 20-30 CFM.

In the case of the same raw material of the heat sink, the air volume is the most important indicator to measure the heat dissipation capacity of the air cooler. Obviously, the higher the air volume, the higher the heat dissipation capacity of the radiator. This is because the ratio of heat to capacity of air is constant, and a larger air volume, that is, more air per unit time can take away more heat.

Of course, the heat dissipation effect is related to the way the air flows with the same air volume. Air volume and wind pressureWind volume and wind pressure are two relative concepts. Generally speaking, to design a fan with a large air volume, some air pressure needs to be sacrificed.

If the fan can drive a lot of air flow, but the wind pressure is small, the wind will not blow to the bottom of the radiator (which is why some fans have a high speed and a large air volume, but the heat dissipation effect is not good). On the contrary, if the wind pressure is large and the air volume is small, there is not enough cold air to exchange heat with the heat sink, which will also cause poor heat dissipation effect. Generally, the heat sink of the aluminum fin requires the air pressure of the fan to be large enough, while the heat sink of the copper fin requires the air volume of the fan to be large enough; Fins with denser fins require a fan with greater air pressure than fins with sparse fins, otherwise the air flow between the fins will not flow smoothly and the heat dissipation effect will be greatly reduced.

Answer: The formula for calculating the air volume of the fan is: n=v*n q, where n is the number of fans (sets); v is the site volume (m3); n is the number of air changes (times); q is the single air volume (m3 h) of the selected fan model. Airflow refers to the total volume of air sent out or inhaled by an air-cooled radiator fan per minute, if calculated in cubic feet, the unit is cfm; If it is calculated in cubic meters, it is CMM, and the air volume unit often used in radiator products is CFM.

Known air volume of 500 cubic hours; Let the wind speed be 20m s:

1. Calculate the diameter of the pipe d(m).

d=q4/(3600υπ)

=2. Calculate the frictional resistance (Pa) along the pipeline

r=(λ/d)(υ2γ/2)

3. Calculate the total resistance: (the resistance of the separator is not considered, and the friction of the elbow and reducer is not considered.) l-pipe length).

H=rl Pipe length (m).

(PA)4, wind speed calculation (m s).

v=q/((d/2)^2*3600)

205. Fan selection:

Considering the air leakage coefficient, select the fan air volume =; , fan pressure =

The wind speed at the air outlet is 50m s, and it should be 50 meters per second from the unit marking. Does 'hourly wind speed' mean 50 metres per hour? Or 50 meters per second? I'll do the math for you after confirmation.

Supplement: 1. Let's take two of the three known conditions to verify the third condition.

When the air outlet is 2 square meters and the flow velocity reaches 50 ms, the flow rate is calculated.

According to the flow formula.

q=νs3600

360000(m3/h)；

When the air outlet is 2m2 and the air volume is 10 cubic meters per minute, the air speed of the air outlet is calculated.

q/(s3600)

When the flow rate is 50m s and the flow rate is 10 60 cubic meters per hour, the tuyere area is calculated.

d=√[q4/(ν

s=(d/2)^2×3,14

0,0033 (sq.m.).

2. According to the calculation results of 1,1, in order to meet the conditions that the air outlet is 2 square meters and the flow velocity reaches 50m s, the air volume needs to reach 360000 (m3 h); According to the calculation results, when the air outlet is 2 square meters, the air volume is 10 cubic meters per minute, and the wind speed is only; According to the calculation results, the flow rate is 50m s, the flow rate is 10 60 cubic meters per hour, and the air outlet area is only one square meter.

3. Conclusion: The conditions you have listed cannot be mutually valid.

New Branch'

I'm having a bit of a problem with wind turbines right now, can I ask you about it? I've sent you a private message.

1. Air volume: The volume flow of gas transported by the fan in a unit time or key is called air volume or flow, usually.

Refers to the amount of gas delivered in the working condition. (Pure unit: m h, m min, m s).

2. Wind pressure: The wind pressure of the fan refers to the full pressure, which is the dynamic pressure.

and the sum of the two parts of static pressure. (Unit: PA);

Dynamic pressure: The pressure represented by the kinetic energy of the gas on the outlet section of the fan is called the dynamic pressure;

Static pressure: The vertical force applied to the unit area of the ventilator.

3. Power: the work done by the fan to the air per unit time. (Unit: kw, w).

4. Efficiency: the output power of the fan.

and the ratio of the input power.

5. Rotation speed: the number of rotations per minute of the fan. (Unit: r min).

6. Specific revolutions:

Specific revolution is a characteristic parameter of the fan, which represents the relationship between the air volume, air pressure and speed of the fan at the highest efficiency point. The fan with a larger specific speed has a large flow rate and low wind pressure; The fan with a smaller specific speed has a small flow rate and high air pressure.

Direction of rotation The fan can be made into two types: right-hand or left-hand. From one end of the motor, the impeller rotates in a clockwise direction called the right cyclone, which is represented by "right"; On the contrary, it is called a left-hand cyclone, which is represented by "left".

I happened to use a fan that you used in a similar way, but I used it for flame retardant burners. The maximum pressure can be up to 70,000pa, and the air volume and wind speed are not a problem.

Refer to Zhangjiagang mattress furnace fan manufacturing ****, according to your current use to buy a centrifugal fan.

If you are afraid of dust, it is recommended to change the vertical air duct.

Although it's not professional.,But I also know.,What you said seems to be called 8 points of inlet.,Wind pressure and air volume have no concept.,But the professional market should have this.,Uh.。。