Maximum limitation of humidification and de-humidification signals
Usually the supply air temperature and the humidity control are independent control loops.
If this would be the case, this control strategy would lead to:
The solution is to limit the humidification and de-humidification signals as function of the supply air temperature control deviation, which otherwise would act as a strong disturbance.
The air handling control strategy already uses the supply air temperature control deviation.
The output signal signal "SAT_ContrDev" from the air handling strategy to the humidification macro transmits this control deviation to the humidifier macro.
The user can connect this signal to enable the limitation functions.
Maximum limitation of the humidification signal
In case of humidification with a steam humidifier the hot steam can heat up the supply air temperature very fast. In this case the cooling coil could be not strong enough to cool against the humidifier and the temperature rises.
Now the coil and the cooling coil could both open 100% and de-humidify the supply air temperature. (waste of energy)
In case the cooling coil is not big enough, the humidification will increase the supply air temperature even above the maximum supply air temperature setpoint.
The solution is to limit the humidification signal, as function of the supply air temperature control deviation.
When the supply air temperature decreases, the control deviation will increase.
When the control deviation is:
Description |
Default value |
HULIM-01: supply air temp. control deviation for maximum humidification signal |
0 K |
HULIM-02: supply air temp. control deviation for minimum humidification signal |
-10 K |
HULIM-03: maximum humidification signal |
100 % |
HULIM-04: minimum humidification signal |
20 % |
Maximum limitation of the de-humidification signal
In case of de-humidification, the cooling coil will be opened to de-humidify.
If the temperature controller detects a too low supply air temperature, the heating coil could open up to 100%.
Now the heating coil and the cooling coil could both open 100%. (waste of energy)
In case the heating coil is not big enough, the de-humidification will decrease the supply air temperature even below the minimum supply air temperature setpoint.
The solution is to limit the de-humidification signal, as function of the supply air temperature control deviation.
When the supply air temperature decreases, the control deviation will increase.
When the control deviation is:
Description |
Default value |
DHLIM-01: supply air temp. control deviation for maximum de-humidification signal |
0 K |
DHLIM-02: supply air temp. control deviation for minimum de-humidification signal |
10 K |
DHLIM-03: maximum de-humidification signal |
100 % |
DHLIM-04: minimum de-humidification signal |
20 % |