(For a more detailed review, please refer to The News’ July 3, 2000 article, “Scroll Technology Starts to Take Off.”)
Within the last 15 to 20 years, however, computer-aided design and manufacturing have made it possible to mass produce a low-cost scroll in high volumes, despite its complicated geometry.
The demand for a quieter, more reliable compressor system was forced on compressor designers because of rising energy costs, federal energy regulations, and increased consumer awareness of sound levels.
The scroll compressor started in residential application, but now its applications have spread to low-temperature systems.
One of the spiral-shaped parts stays stationary while the other orbits around it. This is a true orbiting motion, not a rotating motion.
The orbiting motion causes continuous crescent-shaped gas pockets to be formed. It also causes the gas pockets to become smaller and smaller in volume as they near the center of the scroll form. (See Figure 3.)
Once it reaches the center, the gas pocket is discharged out of a port of the nonorbiting (fixed) scroll member. Several crescent-shaped gas pockets are compressed at the same time, providing for a small and continuous compression cycle.
The intake, compression, and discharge phases are simultaneous and continuous.
When liquid refrigerant, oil, or small particles enter between the two scrolls, the mating scroll parts can actually move apart in a sideways direction. This radial movement eliminates high-stress situations and allows for the right amount of contact force between mating parts.
The scroll requires no valves, so it does not have any valve losses that contribute to inefficiencies. Because a considerable distance separates the suction and discharge ports or locations, heat transfer is reduced between the two.
Because of the scroll’s continuous compression process and the fact that it has no valves to create valve noise, the scroll produces very low gas pulsation noises with hardly any vibration.
The scroll has few moving parts. This enhances its reliability and efficiency.
Soon 18-hp models will be available, the company said. As early as March 2002, selected hp models will be available for use with a full range of refrigerants (22, 407C, and 410A). Tandem compressor configurations will also be available.
Tomczyk is a professor of hvacr at Ferris State University, Big Rapids, MI, and author of the book Troubleshooting and Servicing Modern Air Conditioning and Refrigeration Systems, published by ESCO Press. To order, call 800-726-9696. Tomczyk can be reached at email@example.com (e-mail).
Publication date: 10/01/2001