Why should we check the efficiency range when selecting air-conditioning box fans?

The efficiency of the air conditioning box fan should be checked according to the working point corresponding to the designed air volume and pressure, and the actual adjustment range should also be checked. The maximum efficiency point is just a position on the curve. If the selection point deviates from this range, or the installation conditions change the fan performance, high rated efficiency does not mean actual operation power saving.

1. Mark the design points and common operating points on the curve together

The initial resistance is not the same as the resistance after the filter is used, and the air volume during day shift and low-load operation may also change. When selecting, at least list the design points, common points and reasonable resistance change range, and check the corresponding input power, speed and stable operating range. Selection information that only provides air volume but no pressure makes it impossible to judge efficiency.

Check the air volume, pressure caliber and corresponding input power at the design point; check the load range where most of the operating time occurs at the common point; check the maximum speed, motor load and allowable operating boundaries at the limit point. Pressure caliber is easy to confuse, please refer to the articleWhat is the difference between static pressure, total pressure and static pressure outside the air conditioner box? . For the basic relationship between air volume and pressure, please refer toWhat functional segments should be included in the internal resistance of the air conditioning box?。

2. You also need to install the fan into the box and look again.

The fan inlet is blocked, the outlet is in a sharp bend, or the installation distance is insufficient, which may cause the working point of the whole machine to deviate. Comparing scenarios should use the same air density, accessories and measurement boundaries, and differentiate between fan aerodynamic efficiency, motor efficiency and total input power. Finally, it is confirmed based on the performance data under the agreed working conditions.

The layout of the fan section in the box can be combined withPlease refer to the fan box page to learn about the structural form; for the sequential relationship between the fan and the filter section, please refer to the articleWhat needs to be considered when arranging the filter section before and after the fan? . If the fan outlet connection space is limited, the length of the functional section and maintenance conditions will also be affected. Please refer toCan the length of the horizontal air conditioning box be reduced when there is insufficient plane space?。

3. Why does the DC fan depend more on the working point?

DC electronically commutated fans have different adjustment characteristics under partial load. When selecting, you cannot just compare the nameplate power or the highest efficiency figure. In actual operation, the filter resistance increases with the dust content, the air valve opening changes, and the duty mode reduces the air volume, which will cause the fan to deviate from the original design point. What needs to be confirmed is whether the input power, speed and noise are still within the acceptable range under the common combination of air volume and resistance.

For the driving and power supply conditions of DC fans, please refer to the articleWhat driving conditions need to be matched when using a DC fan in an air-conditioning box? ;For comparison of various fan types, please refer toHow do the backward-inclined and forward-inclined fans compare when used in air conditioning boxes? . When Aili Industrial matches the fan box and air handling unit, it will put the fan, motor and control interface in the same set of data for verification.

4. Efficiency figures must correspond to operating costs

High efficiency does not mean energy saving throughout the year. If the selection point is far away from the high-efficiency area, or the system operates under low air volume for a long time, the actual power may be higher than expected. When comparing plans, the power under the design working conditions, common working conditions and the final resistance state of the filter should be listed separately, and then combined with the operating hours estimate. Only giving a maximum efficiency percentage cannot explain the performance under common working conditions.

For the estimated boundary of annual energy consumption, please refer to the articleWhy can’t the annual energy consumption of air conditioning boxes be estimated based on rated power only? ;For the statistical method of fan power consumption by time period, please refer toHow to calculate the energy consumption of air conditioning box fans separately according to operating periods?。

5. Aili Industrial Supporting Equipment

When communicating with Aili Industrial, you can request that the fan, motor and cabinet layout be put in the same set of selection materials for verification, focusing on comparing the matching degree of the actual use points. Aili Industrial has motor manufacturing and independent fan R&D and production capabilities, which can be matched based on the target air volume, unit internal resistance, external static pressure and speed regulation requirements; in the case of increased resistance after use of the filter, the fan adjustment range and operating margin can be checked during the selection stage to reduce configuration deviations caused by selection only based on rated air volume.

Product form can be viewedfan box andAir handling unit page; clean air supply package can be combinedFFU fan filter unit andEFU equipment end fan filter unit verification; multiple equipment linkage can understandSupporting method of FFU computer group control system ; when it comes to gaseous pollution control, we can communicate separatelyChemical filter solutions. The specific performance, applicable environment and delivery scope still need to be verified based on the corresponding configuration data and on-site working conditions. Actual results are subject to on-site leak detection and performance test results.

Submit project parameters:https://ailigy.com/contactus.html

6. Related questions and answers

Does selecting the model with the highest efficiency point necessarily save energy?
uncertain. The maximum efficiency point is just a position on the curve. If the actual operating point deviates from this range, or the installation conditions change the performance of the fan, high rated efficiency does not mean actual operation power saving.

Is it possible to complete the fan selection by only providing air volume but not pressure?
cannot. Without the pressure caliber and corresponding working conditions, it is impossible to determine the fan operating point and input power, and the selection information is incomplete.

What kind of fan matching checks can Aili Industrial provide?
The fan and motor can be matched based on the target air volume, internal resistance, external static pressure and speed regulation requirements, and the operating margin under common working conditions can be checked. The specific configuration needs to be confirmed according to project conditions.

7. Related articles

1. What is the difference between static pressure, total pressure and static pressure outside the air conditioner box?

2. What functional segments should be included in the internal resistance of the air conditioning box?

3. What driving conditions need to be matched when using a DC fan in an air-conditioning box?

4. Why can’t the annual energy consumption of air conditioning boxes be estimated based on rated power only?

8. Key points for selection and acceptance inspection