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Emerson
 
The beauty of this technology is its inherent simplicity. The standard Copeland Scroll has a unique feature called axial compliance. This allows the fixed scroll to move in the axial direction, by very small amounts, to ensure that the fixed and orbiting scrolls are always loaded together with the optimal force.
This optimal force, which holds the 2 Scrolls together at all operating conditions, ensures high efficiency of Copeland Scrolls. The Digital Scroll operation builds on this principle.
The Digital Scroll operates in two stages - the "loaded state", when the solenoid valve is normally closed and "unloaded state", when the solenoid valve is open. During the loaded state, the compressor operates like a standard scroll and delivers full capacity and mass flow. However, during the unloaded state, there is no capacity and no mass flow through the compressor. |
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| At this stage, let us introduce the concept of a cycle time. A cycle time consists of a "Loaded State" time, and "Unloaded State" time (Figure 2).. The duration of these 2-time segments determine the capacity modulation of the compressor. Example: In a 20-second cycle time, if the loaded state time is 10 seconds and the unloaded state time is 10 seconds, the compressor modulation is (10 seconds x 100% + 10 seconds x 0%)/ 20 = 50% (Figure 3). If for the same cycle time, the loaded state time is 15 seconds and the unloaded state time is 5 seconds, the compressor modulation is 75%. The capacity is a time averaged summation of the loaded state and unloaded state. By varying the loaded state time and unloaded state time, any capacity (10%-100%) can be delivered by the compressor. |
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