According to the theory of hydrodynamics, the flow process of gas will be accompanied by loss. For example, after the gas flows through the throttling device, the pressure of the air flow will be reduced accordingly, that is, they lose the active work of the fan. Because all this happens in the process of gas conveying by the fan, that is, the energy of the fan is wasted.

風機工況點是風機在某一轉速下的性能曲線與管網阻力特性線的交點。風機實際運行時，并非永遠停留在設計工況點上。它將隨用戶的需求或外界條件的變化而變化，也就是風機實際上處于變工況下工作。要想使風機的風壓或風量達到某一目標值，就需要對風機或管網進行為人為地控制，亦稱調節。通過有效地調節，實現在保證風機能夠穩定工作的條件下，既要滿足生產對流量或壓力的要求，又能限度地節能。簡言之，調節的目的就是滿足性能要求，擴大（穩定）工況，實現節能，防止喘振。

The operating point of the fan is the intersection of the performance curve of the fan at a certain speed and the resistance characteristic line of the pipe network. During the actual operation of the fan, it does not always stay at the design working condition point. It will change with the needs of users or changes in external conditions, that is, the fan actually works under variable working conditions. In order to make the air pressure or air volume of the fan reach a certain target value, it is necessary to artificially control the fan or pipe network, also known as regulation. Through effective regulation, it can not only meet the requirements of production for flow or pressure, but also save energy to a certain extent under the condition that the fan can work stably. In short, the purpose of regulation is to meet the performance requirements, expand (stabilize) working conditions, save energy and prevent surge.

風機采用不同的調節方式都可達到同一目的，但節能效果各不相同。

Different adjustment methods of fan can achieve the same purpose, but the energy-saving effects are different.

根據理論分析及實踐證明，可得出如下4個方面的結論。

According to theoretical analysis and practical proof, the following four conclusions can be drawn.

⑴對于鼓風機和壓縮機，出口節流調節方式耗功最多。盡管相對流量Qr（實際流量Q與設計流量Q0之比）減少時，功率亦相應減少。如當Q=0.65Q0時，所對應的功率減少到原來的80%左右，但與其它調節方式相比，耗能仍居重要位置。

(1) for blowers and compressors, the outlet throttling regulation mode consumes the most power. Although the relative flow QR (the ratio of actual flow Q to design flow Q0) decreases, the power also decreases accordingly. For example, when q = 0.65q0, the corresponding power is reduced to about 80%, but compared with other regulation methods, energy consumption still occupies an important position.

⑵如果相對流量變化不大時（或稱調節深度小時），幾種調節方式耗功差別不大。即調節方式對節能效果影響不大，甚至不僅不節能，反而因調節裝置的存在多耗功（如液力耦合器）。

(2) if the relative flow changes little (or the regulation depth is small), there is little difference in power consumption among several regulation modes. That is, the regulation mode has little impact on the energy-saving effect, or even does not save energy, but consumes more power due to the existence of the regulation device (such as hydraulic coupler).

⑶一般來說，調節深度越大，節能效果越顯著。因此，要慎重選擇調節方式，以期獲得效益。

(3) generally speaking, the greater the adjustment depth, the more significant the energy-saving effect. Therefore, we should carefully choose the regulation mode in order to obtain benefits.

⑷變速調節曲線接近理想曲線。所以，變速調節方式優越，特別是采用變頻電動機調速的節能方案為好，但需要增設變頻裝置。對于中小容量的變頻調速建議積極試用；由于大容量高電壓變頻調速裝置價格較高，應結合具體情況，綜合比較，決定取舍。總之，既要考慮調節性能，也要考慮設備初投資、可靠性及經濟性等，全 面評價調節方式的優劣。

(4) the speed regulation curve is close to the ideal curve. Therefore, the variable speed regulation mode is superior, especially the energy-saving scheme of variable frequency motor speed regulation is better, but the variable frequency device needs to be added. It is recommended to actively try out frequency conversion speed regulation with small and medium capacity; Due to the high price of high-capacity and high-voltage variable frequency speed regulation device, the choice should be determined by comprehensive comparison in combination with specific conditions. In short, we should not only consider the regulation performance, but also consider the initial investment, reliability and economy of the equipment, and comprehensively evaluate the advantages and disadvantages of the regulation mode.