(a) Outflow temperature
(b) Ambient temperature
(c) Spectrum of the outflow temperature
Figure 15: Outflow temperature of a  kW cooling system. Panel (a) shows the performance of the outflow temperature. At about 4 p.m., the system reaches its control limits, because the ambient temperature (b) exceeds significantly the set-point (20°C) of the outflow temperature. The high eigenfrequencies of the hydraulic system become visible from about 2:30 p.m. on.