Several energy efficiency indicators of air compressor units
In the context of achieving carbon peak and carbon neutrality, people’s awareness of energy conservation and emission reduction has gradually increased. As an air compressor with high energy consumption, customers will naturally regard its efficiency as an important assessment point when choosing.
With the emergence of various energy-saving service models such as energy-saving equipment replacement, contract energy management, and hosting services in the air compressor market, a series of parameter indicators have emerged for the energy-saving performance of air compressors. The following is a brief explanation of the meaning and meaning of these performance indicators. Briefly describe the interrelationships and influencing factors.
01
Specific power of unit
Unit specific power: refers to the ratio of air compressor unit power to unit volume flow under specified working conditions. Unit: KW/m³/min
It can be simply understood that specific power reflects the power of the unit required to produce the same amount of gas under rated pressure. The smaller the reaction unit, the more energy-efficient it is.
Under the same pressure, for an air compressor unit with a fixed speed, the specific power is directly an indicator of the energy efficiency at the rated point; for a variable speed air compressor unit, the specific power reflects the weighted value of the specific power at different speeds, which is Energy efficiency response to the comprehensive operating conditions of the unit.
Generally, when customers choose a unit, the specific power indicator is an important parameter that customers consider. Specific power is also an energy efficiency indicator clearly defined in “GB19153-2019 Energy Efficiency Limits and Energy Efficiency Levels of Volumetric Air Compressors”. However, it must be understood that in actual use, a unit with excellent specific power may not necessarily be more energy-saving than a unit with average specific power when used by customers. This is mainly because the specific power is the feedback efficiency of the unit under specified working conditions. However, when customers use the air compressor, there is a factor of change in the actual working conditions. At this time, the energy-saving performance of the unit is not only related to the specific power. , is also closely related to the control method of the unit and the selection of the unit. So there is another concept of energy-saving performance.
02
Unit energy consumption of the unit
The specific energy consumption of the unit is the actual measured value. The method is to install a flow meter at the exhaust port of the unit that the customer normally uses to count the exhaust volume generated by the air compressor during the entire working cycle. At the same time, install an electric energy meter on the unit to count the electricity consumed during the entire working cycle. Finally, the unit energy consumption in this working cycle is = total power consumption ÷ total gas production. The unit is: KWH/m³
As can be seen from the above definition, unit energy consumption is not a fixed value, but a test value. It is not only related to the specific power of the unit, but also related to the actual usage conditions. The unit energy consumption of the same machine is basically different under different working conditions.
Therefore, when choosing an air compressor, on the one hand, you must choose a unit with a relatively good specific power. At the same time, customers need to fully communicate with the pre-sales engineer of the air compressor before selecting a model, and the air consumption, air pressure, etc. in use must be fully understood. The situation is fed back. For example, if the air pressure and air volume are constant and continuous, the specific power of the unit has an important impact on energy saving, but the control method is not the main means of energy saving. At this time, you can choose a industrial frequency unit with a double-stage high-efficiency machine head as the selected unit; if the gas consumption at the customer’s site fluctuates greatly, the control method of the unit becomes the main means of energy saving. At this time, you must choose the air compressor controlled by variable frequency machine. Of course, the efficiency of the machine head also has an impact, but it is in a secondary position compared to the energy-saving contribution of the control method.
For the above two indicators, we can make an analogy from the automobile industry that we are familiar with. The specific power of the unit is similar to the “Ministry of Industry and Information Technology Comprehensive Fuel Consumption (L/100km)” posted on the car. This fuel consumption is tested by specified methods under specified working conditions and reflects the fuel consumption at the operating point of the vehicle. So as long as the car model is determined, the comprehensive fuel consumption is a fixed value. This comprehensive fuel consumption is similar to the specific power of our air compressor unit.
There is another indicator for cars, which is the actual fuel consumption of the car. When we drive, we use the odometer to record the total mileage and the actual total fuel consumption. In this way, after the car has been driven for a period of time, the actual fuel consumption can be calculated based on the recorded actual mileage and the actual fuel consumption. This fuel consumption is related to the driving conditions, the car’s control method (such as an automatic start-stop function similar to the automatic sleep wake-up of an air compressor), the type of transmission, the driver’s driving habits, etc. Therefore, the actual fuel consumption of the same car is different under different operating conditions. Therefore, before choosing a car, you must fully understand the working conditions of the car, such as whether it is used at low speeds in the city or frequently on high speeds, so as to choose a car that is suitable for actual use and more energy-saving. This is also true for us to understand the operating conditions before selecting an air compressor. The actual fuel consumption of a car is similar to the specific energy consumption of an air compressor unit.
Finally, let’s briefly explain the mutual conversion of several indicators:
1. Comprehensive specific power (KW/m³/min) = unit energy consumption (KWH/m³) × 60min
2. Comprehensive unit power (KW) = comprehensive specific power (KW/m³/min) × comprehensive gas volume (m³/min)
3. Comprehensive power consumption 24 hours a day (KWH) = Comprehensive unit power (KW) × 24H
These conversions can be understood and remembered through the units of each indicator parameter.
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