Control logic function (i.e. the Deadband Control)

[Kenny Leong]

Hi all,

I have two (2) questions in relation to the control logic function within PyroSim and in particular the Deadband Control (e.g.. Thermostat). Based on my understanding of this control, its function is to select a object to be activated and deactivated based on parameter (e.g. temperature or radiant heat flux) of the device selected to control the object.

Furthermore, the activation criteria has to be higher than de-activation criteria. For example, a sample code within PyroSim would be “Turn off <RAD1> when RAD1 falls below 11.5 kW/m² and turn on when RAD1 rises above 12.0 kW/m²”. This control was used in the PyroSim model and worked perfectly. Based on the above my question is two-fold:

1. Firstly, is there FDS code that can be manually inserted into PyroSim which would allow the de-activation (i.e. turn off) criteria to be higher than the activation (i.e. turn on) criteria; and
2. Secondly, is there FDS code to instruct that the object, when turned on based on the activation (i.e. turn on) criteria, only de-activates after the radiant heat flux (for example) from the simulated fire has risen above the turn off criteria and then once the radiant heat flux (for example) within the simulated fire falls below the turn off criteria the object is de-activated.

The second part of my query is also with respect to control logic function. Is there a function in PyroSim or FDS code which allows you to activate (i.e. turn on) an object based time and then de-activate (i.e. turn off) once the radiant heat flux (for example) within the simulated fire falls below the turn off criteria. As such the same object is based on two (2) different controls. I have tried and am unable to achieve this function.

Thanks in advance for your assistance in this matter it is greatly appreciated.

Kenny

[dr_jfloyd]

If you want to define a function where it is TRUE only in specific ranges, see the CUSTOM function in the User's Guide.

You can use control functions to combine the outputs of control functions in order to build complex logic. See the dry pipe example in the User's Guide.