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Digital Scroll Advantage for Rack Systems
Digital scroll compressors having modulation capabilities from 10%–100% naturally t refrigeration rack systems. Rack systems need to
fulll varying evaporator load requirements due to changing case loads, not to mention variations due to cases undergoing routine defrost.
This can be attained by complementing xed-speed compressor racks with a digital scroll of the same capacity. The refrigeration load will
be matched by running xed-speed compressors to handle the base load and the peaks by the digital scroll. This leads to a smooth and
almost constant system suction pressure (see charts below). Compared to xed-speed scroll racks where unloading is achieved by cycling
the lead compressor, this results in a saw tooth prole of the system suction pressure and will reduce the life of the lead compressor due to
frequent on and off action. Fluctuating suction pressures lead to varying evaporator temperature and humidity conditions—a condition
that is not advisable for refrigerated products.
Compressor modulation by cycling compressor on and off
Saw tooth prole of suction pressure for
xed speed compressor
Compressor modulation by digital scroll
Smooth system suction pressure
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