blockHighMassSupplyTemperature_TSurRelHum
Information
Controller for a radiant cooling system.
The controller tracks the surface temperature set point TSurSet by
adjusting the supply water temperature set point TSupSet
based on the output signal y of the proportional controller.
Both, the surface temperature set point TSurSet and the resulting
supply water temperature set point TSupSet are
limited by the dew point temperature that is calculated based on the inputs
TRoo and phiRoo.
The pump is either off or operates at full speed, in which case yPum = 1.
The pump control is based on a hysteresis that switches the pump on when the output of the
proportional controller y exceeds 0.2, and the pump is commanded off when the output falls
below 0.1. See figure below for the control charts.
ASHRAE Standard 55-2004 recommends that the surface temperature of a radiant floor is above 18°C to avoid discomfort for spaces in which people wear typical footwear.
For systems with high thermal mass, this controller should be left configured as a P-controller, which is the default setting. PI-controller likely saturate due to the slow system response.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | TSupSet_max | 297.15 | Maximum cooling supply water temperature |
| Real | TSupSet_min | Minimum cooling supply water temperature | |
| Control gains | |||
| Controls.OBC.CDL.Types.SimpleController | controllerType | Buildings.Controls.OBC.CDL.Types.SimpleController.P | Type of controller |
| Real | k | 2 | Gain of controller |
| Real | Ti | 3600 | Time constant of integrator block |
| Real | Td | 0.1 | Time constant of derivative block |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Controls.OBC.CDL.Interfaces.RealInput | TSurSet | Set point for room air temperature | |
| Controls.OBC.CDL.Interfaces.RealInput | TRoo | Measured room air temperature | |
| Controls.OBC.CDL.Interfaces.RealInput | phiRoo | Measured room air relative humidity | |
| Controls.OBC.CDL.Interfaces.RealInput | TSur | Measured room air temperature | |
| Controls.OBC.CDL.Interfaces.RealOutput | TSupSet | Set point for cooling supply water temperature | |
| Controls.OBC.CDL.Interfaces.RealOutput | y | Control signal for heating system from P controller | |
| Controls.OBC.CDL.Interfaces.BooleanOutput | on | Outputs true if the system is demanded on | |
| Controls.OBC.CDL.Interfaces.RealOutput | yPum | Pump speed control signal |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| CDL.Psychrometrics.DewPoint_TDryBulPhi | dewPoi | Dew point temperature, used to avoid condensation | |
| CDL.Reals.Hysteresis | hysCoo | Hysteresis to switch system on and off | |
| CDL.Reals.PID | conCoo | Controller for cooling |
Revisions
-
March 29, 2022, by Michael Wetter:
First implementation.
This is for issue 2823.