Pressure Oscillation and the damper function

Pressure oscillation and the
damper function
Pressure [Bar]
Oscillation of the pump discharge pressure
At certain low discharge pressure of the pump, there is no oscillation. With
increase of the pressure, the oscillation starts. The frequency of the oscillation
is about 3 Hz. The amplitude (p2p) is about 1 bar.
Temperature of the damper [˚C]
Pressure [Bar]
Effect of the damper
Damper on (with heating)
Damper off (without heating)
Oscillation is due to not
enough heat load
in the dummy load.
JT valve of the chiller is
Damper has no obvious effect on the damping of the oscillation.
Test station connected with the large scale system
From the large scale system
To the large scale system
Pressure measurement in the test station
Time [s]
 In the test station, the pressure P1 before the JT expansion valve still oscillates with the
same frequency as the discharge pressure of the pump. Much less amplitude (25mbar)
 After JT expansion, the pressure P2 has no oscillation.
It is possibly dampened by the JT expansion valve and the capillary connected with
the pressure sensors P1 and P2.
Suction side pressure before the chiller
Time [s]
The suction side pressure PT1106 before the chiller of the large scale system has no
oscillation too.
It seems the oscillation has no effect on the pressure drop measurement along the
test section.