HRRPUA

[Gary Chen of GHL Consultants Ltd]

I can't seem to find in the FDS5 manual how to prescribe a fire with a
certain reaction.

I understand through HRRPUA we prescribe a fire with a known HRR,
which will be determiend by multiplying the area of the vent.... and
this fire assumes propane. Is there a way that I can define this fire
of known HRRUPA with a custom reac (ie O2, CO2 yields) known from
literature?

Thanks
G

[Kevin]

Yields of CO, soot, etc, are controlled by the REAC line, on which you
specify the number of carbon atoms, C, hydrogen, H, oxygen, O, in the
fuel. CO and soot are controlled by yields, CO_YIELD and SOOT_YIELD.


On Mar 20, 12:04 pm, Gary Chen of GHL Consultants Ltd

[Gary Chen of GHL Consultants Ltd]

Thanks

So do I specify

&REAC ID='Fire1'
C =
CO_YIELD=
...
etc /

&SURF ID='DESIGN FIRE'
HRRPUA=1000
REAC='Fire1'/

?

Thanks
Gary

> > G- Hide quoted text -
>
> - Show quoted text -

[Kevin]

This is why we wrote a User's Guide.

On Mar 20, 1:43 pm, Gary Chen of GHL Consultants Ltd

> > - Show quoted text -- Hide quoted text -

[Gary Chen of GHL Consultants Ltd]

Thanks
It's just that the manual doesn't seem to explicitly state that you
can speicfy HRRPUA + REAC together in what kind of format. As I see
Section 13.22 'Surf' - it doesn't seem to allow me to reference a
different type of reaction

[dr_jfloyd]

From the users manual 9.1. Note the started text:

"There are two ways of designating a fire: the first is to specify a
Heat Release Rate Per Unit Area HRRPUA on a SURF line. The other is to
specify a HEAT_OF_REACTION, along with other thermal parameters on a
MATL line, in which case the burning rate of the fuel depends on the
net heat feedback to the surface. ****In both cases, the mixture
fraction combustion model is used****. In fact, the mere presence of
these parameters automatically invokes the mixture fraction model. Do
not specify explicitly gas species like oxygen if you have also
specified heat release rates or solid phase reaction rates.

*****A single REAC line is used with the mixture fraction model.
****If the REAC line is not found in the input file, propane will be
used as the surrogate fuel, and all burning rates will be adjusted
accordingly****. If you only specify the fire's heat release rate with
HRRPUA, then the reaction parameters may not require adjusting,and no
REAC line need be added to the input file. *******However, if you know
something about the predominant fuel gas, you might want to consider
specifying, at the very least, the basic stoichiometry via the REAC
line.******"

What is unclear that the REAC line is used to specify the fuel
associated with HRRPUA?





Using the mixture fraction model, each reaction is assumed to be of
the form On Mar 20, 7:08 pm, Gary Chen of GHL Consultants Ltd