Atlas Copco GA 110 VSD, Instruction Book

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Water-cooled compressors
Operation
The compressor oil flow is controlled by two by-pass valves (Y152 and Y151 ), ensuring reliable compressor
operation and optimum energy recovery.
Recoverable Energy
The graphs of section Principal data below represent the performance for each power variant of GA90-160+
at reference working pressure. The curves represent the limits of the energy recovery area and were obtained
with the temperature of the element outlet as indicated in the graph. All points below the curve with Tc=85
°C are possible working points where the recovered energy is maximized for lower element outlet
temperatures.
The formula to calculate the amount of recovered energy is:
Q (kW) = 4.2 x q (l/s) x dT (°C)
with
• q = water flow in l/s
• dT = temperature difference between water at inlet and outlet
For a VSD compressor, when running at a lower motor speed, the recoverable energy will be lower, because
the dT that can be reached is smaller. This can be calculated by using the graph for maximum speed (see
“performance curves”) and then recalculating the dT:
Instruction book
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