CD 30 ÷ 520
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7.4 Principle of Digital Scroll Compressor
The fixed vortex plate on the top is allowed to move upwards about 1
mm during the operation of the Digital Scroll. Lifting the top vortex
plate ensures that there is no pumping through the vortex plate, and
there is no mass flow through the compressor. This is the period of
zero capacity for the compressor. This state is called the “Unloading
State” of the compressor. The “Loading State” is the normal state
when the scrolls are operating normally like a standard scroll and the capacity is 100%. It is
important to point out that there is no bypass of gas in this operation. The principle of achieving
modulation is by alternately lifting and engaging the top vortex plate. A cycle time consists of a
“Loading State” time and “Unloading State” time. The duration of these 2 time segment determine
the capacity modulation of the compressor.
Example
: the total capacity is 10HP, cycle time is 20 seconds. If the output power is 5HP(50%of
total capacity),the compressor modulation is(10 sec. h 100%+10sec. h 0%)/20sec.=50%. The
loading state time is 10 seconds and the unloading state time is 10 second. If the output power is
2HP( 20%of total capacity),the compressor modulation is 20%, the state time is 4 sec. and the
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