This model simulates parallel connected cooling tower subsystem with a bypass valve.
The bypass valve is controlled to enforce that the leaving condenser water
temperature does not drop below the minimum temperature TMin.
By default, the condenser water setpoint is the ambient wet bulb temperature
TWetBul plus the approach temperature dTApp. 
Inside the model, a cooling tower fan speed controller is also implemented to maintain the condenser water at its setpoint.
dp_fixed = 0 for the bypass valve because the pressure drop in this leg
will be significantly less than the cooling towers.riseTime for the valve signal filters.
use_inputFilter = false for shut-off valve in cooling tower.
This avoids a sharp rise in pressure near t=35 seconds.