Scroll compressors

Scroll compressors (also called spiral compressors) are positive-displacement machines widely used in HVAC, refrigeration and heat-pump systems. They contain two interleaved spiral scrolls one fixed and one orbiting that trap and squeeze refrigerant vapor. As the motor-driven orbiting scroll moves eccentrically (off-center) around the fixed scroll, it continuously traps and pushes refrigerant toward the center at rising pressure. This smooth, pulseless compression (with no metal-on-metal contact) makes scroll units compact, quiet and highly reliable.

In the cutaway image you can clearly see the key parts. The orbiting scroll (bolted to the shaft) nests inside the fixed scroll. Surrounding the shaft is the stator (stationary motor coils) and rotor - together they drive the orbiting scroll. Refrigerant enters at the low-pressure suction port, gets caught in the spiral pockets between the scrolls, and is compressed as those pockets shrink toward the center. The high-pressure gas then exits through the central discharge port. The labels in this cross-section - fixed/orbiting scrolls, stator/rotor, suction and discharge lines make it easy to trace the refrigerant flow path.

This detailed cross-section is a great learning tool. It "reveals internal components... scroll elements, [suction and discharge] chambers, [and] motor windings", and lets students "observe scroll elements: fixed and orbiting scrolls, and analyze suction and discharge chamber design" to understand how the compressor works. Seeing each part in context really helps demystify the refrigeration cycle.

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