Inert Gas/Clean agent fire suppression systems (CO2, Argon, FM200, Novec 1230)

[K Fung Yew]

Hello guys,

I am trying to do a simulation of a room with inert gas or clean agent as the main fire suppression system. For my system, I've selected Novec 1230, and have input most of the data available on the catalog. The problem that I'm facing now is that it seems like the particles behaved like liquid instead of gas, which they are supposed to. Furthermore, the suppression mechanism is actually removing heat from the fire tetrahedron and therefore stopping the fire, and I am not sure if FDS v6 can support this simulation.

The HRR behaves weirdly, it ramps up in the function of t square, and dip a little when the agent is released. However it continues to go up after a few seconds.

I hope that you guys can shine some light on this, and let me know whether gaseous suppression system is possible or not with FDS. Thank you!

[Randy McDermott]

I am not understanding your question.  Did you enter the agent as particles?  Or did you enter it via a gas VENT?  Please create a minimal input file and perhaps an image or plot to describe was it going on and what you think should be going on.  Thanks.

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[K Fung Yew]

Sorry for the confusion. I entered the agent as particles through nozzle, current setting is 5000 particles per sec per nozzle. Thank you for the reply :)

&PROP ID='Novec', PART_ID='Novec', K_FACTOR=4.0, OPERATING_PRESSURE=16.5, ORIFICE_DIAMETER=0.0061, SPRAY_ANGLE=50.0,75.0/

&PART ID='Novec', SPEC_ID='Novec', DIAMETER=500.0, MONODISPERSE=.TRUE., RGB=240.0,0.0,255.0, AGE=10.0, SAMPLING_FACTOR=1/

&SPEC ID='Novec', FORMULA='C6F12O', SPECIFIC_HEAT=0.891, REFERENCE_TEMPERATURE=49.0, REFERENCE_ENTHALPY=114.47, DENSITY_LIQUID=1600.0, SPECIFIC_HEAT_LIQUID=1.103, VAPORIZATION_TEMPERATURE=48.0, MELTING_TEMPERATURE=-108.0, HEAT_OF_VAPORIZATION=88.0/

On Friday, February 10, 2017 at 10:57:43 PM UTC+8, Randy McDermott wrote:

I am not understanding your question.  Did you enter the agent as particles?  Or did you enter it via a gas VENT?  Please create a minimal input file and perhaps an image or plot to describe was it going on and what you think should be going on.  Thanks.

On Fri, Feb 10, 2017 at 9:45 AM, K Fung Yew <yewk...@gmail.com> wrote:

Hello guys,

I am trying to do a simulation of a room with inert gas or clean agent as the main fire suppression system. For my system, I've selected Novec 1230, and have input most of the data available on the catalog. The problem that I'm facing now is that it seems like the particles behaved like liquid instead of gas, which they are supposed to. Furthermore, the suppression mechanism is actually removing heat from the fire tetrahedron and therefore stopping the fire, and I am not sure if FDS v6 can support this simulation.

The HRR behaves weirdly, it ramps up in the function of t square, and dip a little when the agent is released. However it continues to go up after a few seconds.

I hope that you guys can shine some light on this, and let me know whether gaseous suppression system is possible or not with FDS. Thank you!

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[Kevin]

I suggest that you model the spray only. No fire. Compare your results with an actual experiment to determine if the liquid droplets are evaporating appropriately. It is not possible for us to know what to expect in this very special case. You must do some verification calculations to make sure that the code is doing what is expected.

[K Fung Yew]

Thank you Kevin.

In real life, the Novec 1230 system is stored as liquid but dispersed as gas through the nozzles. I am trying to determine whether gaseous fire suppression agent is possible in FDS, be it Novec 1230, FM200, Argon, Nitrogen or any other gaseous agent, and if it's possible, how?

Thank you guys :)

[Kevin]

Your VAPORIZATION_TEMPERATURE is 48 C. Without heat, your droplets will remain liquid.

[K Fung Yew]

Thank you Kevin. Yes I've tried lowering that down to 10C, it should be in gaseous form under room temperature. But during the simulation it still behave like liquid and doesn't move around erratically like how gaseous would behave.

My particle per second is set at 5000, I've upped that to 10000 and result is still quite the same.

[dr_jfloyd]

I recommend you read Yukka Vaari's paper on the extinction model in FDS. You can read it for free on the IAFSS website. That will give you some idea of the current capabilities of FDS.

[dr_jfloyd]

Jukka not Yukka.