To understand scroll compressors, it helps to know that air can be compressed in two main ways: dynamic compression and displacement compression.
A scroll compressor belongs to the displacement type and is commonly used in air conditioners, refrigerators, heat pumps, and cars.
What Are Scroll Compressors?
A scroll compressor, sometimes called a spiral compressor or scroll pump, is a positive-displacement machine that compresses air or gas inside its chamber.
These compressors can be oil-lubricated or oil-free. Oil-free models are used when the air must stay completely clean and dry.
How Scroll Compressors Work
Inside a scroll compressor, there are two spiral-shaped parts called scrolls. One scroll stays still, while the other moves in small circular motions.
As the moving scroll orbits, air is pulled in from the inlet at the top. The air gets trapped between the two scrolls and becomes squeezed as it moves toward the center.
When the air reaches the middle, it is fully compressed and pushed out through a central outlet.
A valve prevents the air from flowing backward. The two scrolls stay stable because they move 180 degrees out of phase, which also helps reduce air leakage.
Main Parts of a Scroll Compressor
A cooling fan removes heat so the machine does not overheat.
Air first enters through the suction opening into the suction chamber. Inside the compressor, the fixed scroll forms one side of the compression chamber, while the orbiting scroll moves around it to compress the air.
A temperature sensor protects the compressor by shutting it down if it gets too hot. The air leaves through the delivery opening after it is compressed.
Advantages and Disadvantages of Scroll Compressor
Scroll compressors are known for being quiet, compact, and reliable. Their simple design includes only one moving part, so they make less noise and experience fewer mechanical problems than piston or screw compressors.
However, scroll compressors usually cost more at the beginning, and they cannot handle extremely large air volumes, which limits their use in high-capacity situations.
Efficiency and Noise
A scroll compressor is highly efficient because its discharge port design allows it to compress more air while using less power. Since the entire compression cycle takes about two and a half turns, the machine provides a steady flow of air without pressure pulses. The balanced movement of the scrolls produces very little vibration, which is why scroll compressors are much quieter than many other types.
How Do They Make Refrigeration Systems Quieter?
They Have Only One Main Moving Part
A scroll compressor uses just one orbiting scroll moving around a fixed scroll. Because there are no pistons slamming up and down, the machine produces much less mechanical noise and fewer vibrations.
The Compression Process Is Smooth and Continuous
Inside the compressor, the air or refrigerant is squeezed in a gentle, steady motion instead of sudden pulses. This smooth action creates almost no pressure spikes, which reduces noise even more. The compression cycle takes about 2.5 turns, and all steps—suction, compression, and discharge—happen at the same time, making the sound level very low.
There Is Very Little Vibration
The orbiting scroll moves in a balanced, circular path, so the compressor does not shake like piston compressors do. Less vibration means less noise traveling through the pipes, cabinet, and the whole refrigeration system.
Choosing the Right Scroll Compressor
When selecting a scroll compressor, it is important to think about the size you need, the airflow you require, and the air quality level your application demands.
You should decide whether you need an oil-free machine or a lubricated one. If you need more airflow, you can choose models that contain two or four scroll elements.
In some cases, buying one large compressor is cheaper than buying several smaller ones. Scroll compressors are also known for being reliable and easy to maintain because they have fewer parts than reciprocating machines.
Common Applications Except Refrigeration
Scroll compressors are used in many industries because they are clean, efficient, and dependable.
Laboratories use them for cleanrooms and testing equipment.
Hospitals and clinics rely on them for ventilators, incubators, and surgical tools.
Electronics manufacturers use them to keep moisture away from sensitive components.