The difference between scroll air compressor and single screw
There are significant differences in structure, working principle, performance characteristics and application fields between scroll air compressor and single screw air compressor. The following is a specific comparison:
1. structural differences
- scroll
- core Components: It is composed of a movable scroll and a fixed scroll, both of which have the same shape but the angular phase positions are staggered by 180 °. The moving coil revolves around the static disk to form a plurality of closed crescent-shaped compression chambers.
- Structural features: No reciprocating parts, only one moving part (moving plate), compact structure, small size, small number of parts, and fewer wearing parts.
- Single screw type
- core Components: A meshing pair is composed of a cylindrical screw and two symmetrically arranged flat star wheels. The screw groove, the inner wall of the casing and the tooth surface of the star gear together constitute the working volume.
- Structural features the symmetrical arrangement of the star wheels balances the radial force and the axial force of the gas to support high-speed operation, but the moving parts include three rotating shafts (two star wheels of the screw), and the structure is relatively complicated.
2. working principle difference
- scroll
- compression process: The gas enters from the suction port on the periphery of the static disk. With the revolution of the moving disk, the crescent-shaped air cavity gradually moves to the center, the volume decreases, the pressure increases, and finally it is discharged from the exhaust port on the center of the static disk.
- Features: The process of suction, compression and exhaust is carried out continuously at the same time, the pressure rise is gentle, the torque change is small, and the vibration is low.
- Single screw type
- compression process: The rotation of the screw drives the star wheel to rotate, and the gas is closed and compressed in the screw groove. As the depth of the screw groove decreases, the gas pressure increases, and finally it is discharged through the exhaust hole.
- Features: The screw completes multiple compression cycles (such as 12 times) per rotation, with high exhaust frequency and small airflow pulsation.
Comparison of 3. performance characteristics
| contrast Item | scroll air compressor | single screw air compressor |
|---|---|---|
| vibration and noise | very low vibration, noise is usually less than 65dB | low vibration, noise less than 75dB (oil injection machine type may produce noise due to oil flow) |
| efficiency | high efficiency under medium and small flow, the compression ratio should not be too large (usually ≤ 10) | single-stage pressure ratio can reach 8~13 (fuel injection machine type), wide working condition adaptability |
| reliability | few moving parts, no wear (only meshing), long life (design life of more than 10 years) | high reliability, but bearings and seals require maintenance, and life is affected by lubrication methods |
| maintenance complexity | simple maintenance without frequent replacement of parts | the lubricating oil and filter element (injector type) need to be replaced regularly, and the oil-free model needs water cooling or special materials. |
| Cost | high machining precision, large initial investment | the rotor processing is complex and the equipment cost is high, but the long-term operating cost is low (fuel injection machine type) |
| lubrication method | can be designed as oil-free models to provide clean air | the injector type relies on oil lubrication, and the oil-free type can be lubricated with water, but the scale and wear problems need to be solved. |
4. application field differences
- scroll
- advantage Scenarios: Places with high requirements for noise and vibration (such as offices, hospitals, laboratories), as well as air conditioning, refrigeration, heat pumps, automobiles, food, medical and other industries.
- Oil-free model: It is suitable for medical treatment, food processing and other fields with strict air quality requirements.
- Single screw type
- advantage Scenarios oil and gas (pressurization, transportation), large industrial refrigeration (cold storage, central air conditioning), chemical process (liquid resistance, multi-phase mixed transmission).
- Oil-free model suitable for pharmaceutical/food grade gas compression, but need to solve the maintenance problem of water lubrication system.
Involvement of 5. Air Compressor without Oil and Water Lubrication
- scroll type oil-free model: Through high-precision processing and sealing design, oil pollution is completely avoided, and it is suitable for scenarios that require extremely high air cleanliness.
- Single screw type oil-free type: Water is used instead of oil for lubrication and cooling, and circulating water needs to be replaced regularly and scale is cleaned up. The maintenance complexity is higher than that of scroll type, but oil-free compressed air can be provided.
