Scroll Expander Produces 1 kW of Quiet Power
The rotary scroll design provides quiet, balanced, pulse-free operation with a noise level of just 50 dBa. The operating element of a scroll compressor is made up of two identical involutes which form right- and left-hand components. One scroll is indexed or phased 180 degrees with respect to the other to allow the scrolls to mesh. This indexing creates crescent shaped gas pockets, bounded by the involutes and base plates of both scrolls.
In operation, one scroll remains fixed; the other is attached to an eccentric that drives a generator shaft. As the moving scroll orbits around the fixed scroll, the tiny pockets formed by the meshed scrolls at the center follow the spiral outward and enlarge in size. The expander inlet is at the center of the scrolls. The entering gas is trapped in two diametrically opposed gas pockets and expands as the pockets move toward the periphery, where the discharge port is located. No valves are needed, which reduces noise and improves the durability of the unit.
Because scroll expanders use true rotary motion, they can be dynamically balanced for nearly vibration-free operation. Power delivery is continuous, which virtually eliminates pulsation and associated noise. Reliability is inherent, because there are only two primary moving parts, with no inlet or discharge valves to break or make noise, and no associated valve losses.