Relationship between air compressor displacement and pressure

There is a close relationship between air compressor displacement and pressure, which is affected by many factors, including air compressor structure, compression process, load, temperature and system design and operation regulation. The following is a detailed explanation of this relationship:

the relationship between 1. compression ratio and exhaust pressure and exhaust volume

• definition of compression ratio: Compression ratio is the ratio of exhaust pressure to intake pressure, and it is one of the key factors to understand the interaction between exhaust pressure and exhaust volume.
• Effect of compression ratio: In a screw air compressor, when the compression ratio increases, it means that the exhaust pressure increases relative to the intake pressure. As the compression ratio increases, the air is compressed more severely between the screw rotors and the density of the air increases. However, a high compression ratio will reduce the compressibility of the air and increase the risk of air leakage during compression. This is because at a high compression ratio, the pressure difference between the screw rotors increases, and air is more likely to leak out from the small gaps between the rotor and the casing and between the rotor and the rotor. This leakage will reduce the amount of air that actually participates in compression and is discharged, thereby reducing the amount of exhaust gas.

Influence of 2. speed on displacement and pressure

• definition of rotational speed: The speed of the screw air compressor is an important operating parameter that affects the exhaust pressure and exhaust volume.
• Effect of speed: The increase in speed will make the screw rotor complete more suction, compression and exhaust cycles per unit time. Within a certain range, the increase in speed will lead to an increase in intake and exhaust volume. However, too high a speed may result in the air in the screw rotor residence time is too short, can not be fully compressed, thereby affecting the further increase of the exhaust pressure. At the same time, high speed will increase the wear and mechanical vibration of the rotor, which may destroy the normal operating state of the compressor, resulting in unstable or even reduced exhaust pressure.

Effect of 3. load variation on displacement and pressure

• effect of increased load: When the load of the screw air compressor increases, that is, the demand for compressed air by the downstream air equipment increases, and the air compressor needs to provide more air. In this case, if the air compressor has enough capacity adjustment, it will try to meet the load demand by increasing the suction volume, thereby increasing the exhaust volume. However, if the compressor is close to its design limit, increasing the load may cause the exhaust volume to fail to meet the demand, and may cause the exhaust pressure to fluctuate.
• Effect of load reduction: When the load decreases, the exhaust pressure may increase. Excessive exhaust pressure can cause damage to equipment and piping if not properly controlled.

Effect of 4. temperature on exhaust volume and pressure

• effect of intake air temperature: Changes in intake air temperature will change the density of the air. When the intake air temperature increases, the air density decreases, and under the same screw rotor volume, the intake air mass decreases, which leads to a decrease in exhaust volume. At the same time, the increase of intake air temperature will make the temperature rise in the compression process larger, which may affect the performance and reliability of the compressor. At high intake temperatures, to achieve the same discharge pressure, the compressor may need to consume more energy, and a more powerful cooling system may be required to control the temperature.
• Effect of temperature during compression: During the compression process, the air temperature will increase. If the temperature is too high, on the one hand, the compressibility of the air will change, which will affect the stable increase of the exhaust pressure; on the other hand, the high temperature may cause the performance of the lubricating oil to decrease (if there is a lubricating oil lubrication system) and increase the difference between mechanical parts. The friction affects the normal operation of the screw rotor, and then affects the displacement.

Influence of 5. system design and operation regulation on displacement and pressure

• impact of the piping system: The pipeline system connected by the screw air compressor has an important influence on the exhaust pressure and exhaust volume. If the pipe diameter is too small or the length is too long, it will increase the resistance of air flow. In this case, in order to maintain a certain exhaust volume, the air compressor needs to increase the exhaust pressure to overcome the pipe resistance. For example, by adjusting the opening of the intake valve, the rotation speed of the screw rotor and other parameters to balance the relationship between the exhaust pressure and the exhaust volume.
• Regulation of control system: When the exhaust pressure is too high, the control system can reduce the intake air volume or reduce the speed to reduce the exhaust pressure, and at the same time adjust the exhaust volume accordingly; when the exhaust volume is insufficient, the speed can be increased or the intake air can be increased. To meet demand. However, attention should be paid to avoid the stability of the exhaust pressure due to excessive adjustment.

In summary, there is a complex relationship between the displacement and pressure of the air compressor, which is affected by many factors. In practical applications, it is necessary to select the appropriate air compressor model and parameter settings according to the specific use scenario and requirements to achieve the optimal balance of exhaust volume and pressure.